Hip

Hip and groin injuries in soccer players can be separated into 3 main categories based on the Doha Agreement:⁶ (1) defined clinical entities for groin pain, (2) hip-related groin pain, and (3) other causes of groin pain in athletes. Defined clinical entities include adductor-related, iliopsoas-related, inguinal-related (sports hernia/athletic pubalgia), and pubic-related groin pain; while hip-related groin pain includes hip morphologic abnormalities, labral tears, and chondral injuries. Included in other causes of groin pain are injuries not clinically defined. The Doha Agreement has acknowledged that not all causes of groin pain fit into the classification system including injuries of the rectus femoris, but they will be included under defined clinical entities for groin pain in this review. While they are not a cause of groin pain, proximal hamstring and gluteal and piriformis injuries are important causes of posterior and lateral hip pain in soccer players and will also be covered in the first section of this review.

DEFINED CLINICAL ENTITIES FOR GROIN PAIN IN SOCCER ATHLETES

ADDUCTOR-RELATED GROIN PAIN

Acute groin pain in soccer players is most commonly caused by muscle strain.⁷ Of the muscle strains, 66% involve the adductor longus, 25% the iliopsoas, and 23% the rectus femoris.⁷ The Doha Agreement defines adductor-related groin pain as adductor tenderness and pain on resisted adduction.⁶ Adductor longus strains in soccer players are typically noncontact injuries (62.5%) and most commonly the result of kicking (40%).^7-9 Many athletes will remember a pop at the time of the original injury.⁹ The combination of history and physical examination is usually sufficient for diagnosis; however, magnetic resonance imaging (MRI) may be helpful in complicated situations with a reported 86% sensitivity and 89% specificity.¹⁰ The average playing time lost is 2 weeks.⁵ Management includes rest, anti-inflammatory medication, physical therapy with core strengthening, and avoidance of aggressive stretching. While partial and distal avulsions can heal with conservative measures, proximal osseous and retracted avulsions of the adductor longus can be treated surgically.¹¹

Continue to: ILIOPSOAS-RELATED GROIN PAIN...

Iliopsoas strains account for 25% of acute groin strains and typically result from an impact that causes eccentric overload while kicking the ball.^7,12 Iliopsoas-related groin pain is defined by the Doha Agreement as groin pain that is reproducible with resisted hip flexion or hip flexor stretch.⁶ Iliopsoas strains respond well to conservative treatment such as rest, anti-inflammatory medication, and physical therapy. Rarely do these athletes become surgical candidates in the acute setting. Chronic cases of iliopsoas pathology occasionally require an arthroscopic intervention.

INGUINAL-RELATED GROIN PAIN

Inguinal-related groin pain is one of the most misleading diagnoses in sports because of its poorly defined and under-researched nature. The varying nomenclature of this entity illustrates the heterogeneity and includes sports hernia,^9,13-15 athletic pubalgia,¹⁶ core muscle injury,¹⁷ athletic hernia,¹⁸ Gilmore’s groin,¹⁵ osteitis pubis,¹⁹ sportsman’s hernia,^20,21 sportsmen’s groin,²² symphysis syndrome,²³ and inguinal disruption.²⁴ It is important to realize that in inguinal-related groin pain, regardless of the nomenclature, there is no true hernia present. The Doha Agreement has defined inguinal-related groin pain as “pain in the location of the inguinal region with associated tenderness of the inguinal canal,” which “is more likely if the pain is aggravated with resistance testing of the abdominal muscles or on Valsalva/cough/sneeze.”⁶ The condition is a painful soft tissue injury in the groin or inguinal area, involving a constellation of various anatomic areas including the abdominal musculature, sacroiliac joint, neural structures, pubic symphysis, adductors, and hip joint. This may account for up to 50% of chronic groin pain.^25,26

One important theory in the development of inguinal-related groin pain is its relationship with femoroacetabular impingement (FAI). Cadaver studies demonstrate that cam deformities cause a 35% increase in motion at the pubic symphysis altering the biomechanics of the adductors and abdominal musculature and, with repetitive stress, may lead to tearing or attenuation of the transversalis fascia, rectus abdominis, internal obliques, and/or external obliques.^12,27,28 Another prevailing theory of this is that the increased pubic stress causes weakness in the posterior portion of the inguinal canal, which then stretches and entraps the genitofemoral, ilioinguinal, lateral femoral cutaneous, or obturator nerves, ultimately causing pain.^28,29

Physical examination findings include pain over the conjoined tendon, pubic tubercle/symphysis (present in 22% of patients), adductor origin (36%), and inguinal ring.^25,30 Pain with resisted sit-ups is present in 46% of patients and pain with coughing/Valsalva is present in 10%.^25,30,31 Selective injections can be a critical part of the evaluation to differentiate inguinal-related groin pain from FAI, osteitis pubis, and adductor strains while helping to determine the appropriate treatment.^25,32 The role of advanced imaging is unclear as the clinical entity is still uncertain and the standard imaging findings have not been definitively established.³³ However, several studies have reported MRI findings suggestive of inguinal-related groin pain. One of the more common MRI findings is the “secondary cleft sign,” which requires injecting a dye into the pubic symphysis.³⁴ Several studies have shown that the radiographic dye extravasates preferentially into the side where the groin symptoms exist and are thought to be secondary to micro-tearing at the common attachment of the musculotendinous structures to the anterior pubis.^34,35 However, it should be noted that the lack of imaging findings does not exclude the possibility of inguinal-related groin pathology.

Initial treatment consists of rest, anti-inflammatory medication, injections, and physical therapy with core strengthening.²⁵ A study by Paajanen and colleagues³⁶ suggested that early surgical intervention may be preferred over conservative management in a randomized trial comparing physical therapy, injections, anti-inflammatory medication, and rest vs an extraperitoneal laparoscopic mesh repair behind the pubic symphysis. In the conservative group, 20% of athletes returned to sport at 1 month, 27% at 3 months, and 50% at 12 months.³⁶ In comparison, the surgical group had 67% return to sport at 1 month, 90% at 3 months, and 97% at 12 months.³⁶ If surgical management is chosen, there are a variety of surgical options including laparoscopy, open or mini-open repairs of the abdominal musculature/fascia or pelvic floor with and without mesh, neurolysis, and adductor release. Muschawek and Berger³⁷described a series of 129 patients that had an open-suture repair of the posterior wall of the inguinal canal with 67% of professional athletes returning to sport within 2 weeks and 83.7% of athletes returning to sport overall. The rates of return to play are consistently 80% to 100% without demonstrated superiority of one technique over another up to this point.³⁰

Continue to: PUBIC-RELATED GROIN PAIN...

Pubic-related groin pain is defined as tenderness to palpation over the pubic symphysis and adjacent bone.⁶ Osteitis pubis is a chronic overuse injury characterized by localized pain to the pubic symphysis and is believed to be caused by repetitive microtrauma from a dynamic rotation of the sacroiliac joint with suggested imbalances between the rectus abdominis and the adductor musculature.^12,38 In soccer players, the condition may be related to the constant torsional stresses of kicking, running, or twisting.¹² If performed, radiographs often show lytic areas of the pubic symphysis, widening of the symphysis, sclerosis, and cystic changes, while bone marrow edema may be present on MRI.³⁸Management consists of rest, anti-inflammatory medication, and corticosteroid injections with gentle stretching once asymptomatic.^12,39

RECTUS FEMORIS INJURIES

The most common injury to the rectus femoris is a strain as a result of an eccentric overload while a soccer player is hit trying to extend his or her leg to kick a ball.¹² In pediatric soccer athletes, an avulsion of the anterior inferior iliac spine from the direct head of the rectus femoris is the second most common avulsion injury.⁴⁰ Radiographs are diagnostic and can help determine treatment. Most avulsions are minimally displaced and can be treated conservatively, but surgical intervention should be considered for an avulsion >2 cm.¹²

PROXIMAL HAMSTRING INJURIES

Proximal hamstring injuries are important causes of acute posterior hip pain and are caused by an eccentric overload in hip flexion and knee extension.²⁵ In soccer players, the typical mechanism is that the planted leg slipping on the playing turf creates a sudden violent flexion of the hip with the knee in an extended position. While relatively uncommon, when a significant avulsion occurs in a professional athlete, surgical intervention is often necessary. In general, these injuries may involve partial or full avulsions off the ischial tuberosity or separation of the bony apophysis in pediatric athletes. A physical examination in the acute setting typically demonstrates massive posterior thigh ecchymosis, a palpable defect, and/or weakness with knee flexion. Imaging is helpful to confirm the diagnosis and evaluate for surgical repair. Radiographs may show a bony avulsion, which is more commonly seen in pediatric apophyseal avulsions. MRI can be used to differentiate a complete tear (involving all 3 tendons) vs a partial tear and evaluate for retraction of the tendon distally. Complete and partial tears of 2 tendons with retraction of >2 cm should be surgically repaired.²⁵ Partial tears without tendon retraction may be treated conservatively with rest, anti-inflammatory medication, and physical therapy and then followed later by a hamstring prevention program.²⁵ We have found that biologic augmentation with platelet-rich plasma can help accelerate healing in partial thickness injuries; however, the evidence is conflicting.

GLUTEAL INJURIES

Chronic overuse injuries of the gluteal musculature are common causes of lateral hip pain. Abductor overuse caused by weakness in the gluteus medius with a normal tensor fascia lata can cause pain with sitting and side-lying.²⁵Overuse of the gluteal muscles with muscular imbalances along with increased tension on the iliotibial band can lead to greater trochanteric pain syndrome.²⁵ A physical examination may demonstrate tenderness over the greater trochanter bursa and positive flexion, abduction, and external rotation testing.²⁵ Abductor overuse syndrome and greater trochanteric pain syndrome are best treated with anti-inflammatory medication and physical therapy to balance the core/pelvic musculature.⁴¹

PIRIFORMIS INJURIES

Piriformis syndrome is a compressive neuropathy of the sciatic nerve. The mechanism of injury in the athlete is through a minor trauma to the buttock or pelvis.^25,42,43 Presenting symptoms include pain with sitting and internal rotation of the hip.¹² Zeren and colleagues⁴² published the only study that includes 2 cases of bilateral piriformis syndrome in professional soccer players. The diagnosis was confirmed with electromyography that was negative at rest and positive when measured after running.⁴² The athletes exhausted conservative treatment with physical therapy, anti-inflammatory medications, injections, and rest and were treated with surgical decompression.⁴² Both players returned to professional soccer after 6 months and played for an average of 7 years.⁴²

Continue to: HIP-RELATED GROIN PAIN IN SOCCER ATHLETES...

HIP-RELATED GROIN PAIN IN SOCCER ATHLETES

Hip-related groin pain has garnered more attention in the last several years after being a previously underdiagnosed entity. One study found that practitioners treated groin pain in athletes for 7 months on average before recognizing that the pathology was intra-articular.⁴⁴ FAI, labral tears, and chondral injuries are the major intra-articular pathologies that cause groin pain in athletes and ultimately impaired performance.^45,46

FEMOROACETABULAR IMPINGEMENT

FAI is caused by pincer-type, cam-type, or combined-type deformities. Pincer lesions are defined as an increased acetabular overhang, while cam lesions are described as an increased bone at the femoral head/neck junction. These deformities in isolation or in combination cause decreased hip motion and increased contact pressures between the anterolateral acetabulum and femoral head-neck junction, which may ultimately lead to labral tears, chondral lesions, and osteoarthritis.⁴⁷ During hip flexion, cam deformities impact the anterolateral acetabulum, preferentially causing articular cartilage damage, while sparing the labrum.²⁵ Conversely, pincer deformities cause repetitive microtrauma to the labrum, crushing it between the acetabular rim and femoral neck with secondary damage to the articular cartilage.²⁵ Over time, the damage to the labrum and articular cartilage may lead to premature osteoarthritis, which occurs at a much younger age in the athletic population.⁴⁸

We know from previous studies that soccer athletes have a high prevalence of morphologic abnormalities of the hip, most commonly FAI. Gerhardt and colleagues⁴⁹ documented the prevalence of hip morphologic abnormalities in elite soccer players and found abnormalities in 72% of men and over 50% of women. It should be noted that this series looked at asymptomatic athletes; however, it has been shown that hip dysmorphia is a risk factor for hip and groin injuries and may provide an opportunity for injury prevention strategies.⁵⁰

Physical examination findings in FAI include decreased hip internal rotation and pain with provocative testing. Wyss and colleagues⁵¹ measured hip internal rotation in athletes with and without FAI. They found that the athletes with FAI have an average of 4° of internal rotation compared with that of the non-FAI athletes with 28°.⁵¹ A worsening internal rotation deficit has been linked to increasing severity of the deformity and when <20° was correlated with joint damage.⁵¹ Provocative testing has a high sensitivity with a recent meta-analysis demonstrating the most sensitive tests to be the anterior impingement test (flexion-adduction-internal rotation) with 94% to 99% sensitivity and the flexion-internal rotation test with 96% sensitivity.⁵² While provocative tests are sensitive, there is no current consensus on physical examination findings that are specific in the diagnosis of FAI.⁶ Diagnosis is made with both positive physical examination and radiographic morphologic findings (alpha angle >55°).³³ Advanced imaging with an MRI arthrogram can be helpful in diagnosing underlying injuries such as labral tears in athletes presenting with compatible symptoms.

Symptomatic patients are typically treated surgically through either open or arthroscopic procedures, which have favorable and comparable functional results, biomechanics, and return to sport.⁵³ In soccer players, return to sport at the professional level after arthroscopic surgery was found to be 96%.⁵⁴ Players returned to sport on average 9.2 months postoperatively and played an average of 70 games after surgery.⁵⁴

Continue to: LABRAL TEARS...

Labral tears present with groin pain, limited hip range of motion, and symptoms of catching, locking, and instability.²⁵Causes of labral tears include trauma, FAI, hip dysplasia, capsular laxity, and degeneration.⁵⁵ Labral tears rarely occur in isolation and have a high association (87%) with morphologic abnormalities of the hip, most commonly FAI and occasionally dysplasia.^56,57 Physical examination findings include positive anterior impingement tests (flexion-adduction-internal rotation) in athletes with anterior labral tears and, less commonly, positive flexion, abduction, and external rotation tests for athletes with lateral and posterolateral labral tears.⁵⁷ Radiographic imaging is used to evaluate for concurrent morphologic abnormalities of the hip, and MRI arthrogram is used to confirm the diagnosis of a labral tear with a sensitivity of 76% to 91%.⁵⁸ Initial treatment consists of conservative treatment, which includes rest, anti-inflammatory medication, activity modification, and physical therapy. In patient refractory to conservative treatment, arthroscopic surgery is effective with high rates of return to sport.⁵⁹ It is important to note that when treating labral tears surgically, any morphologic abnormality needs to be addressed to prevent recurrence of the tear.

CHONDRAL INJURIES

Focal chondral lesions in the hip are commonly found in athletes with FAI and labral tears during arthroscopic evaluation.⁶⁰ Full-thickness defects and unstable flaps in weight-bearing areas are indications for surgical intervention with microfracture.⁶⁰ There are no studies examining the efficacy of microfracture in isolation; however, Locks and colleagues⁵⁴ have demonstrated a 96% return to professional soccer after an arthroscopic treatment for FAI and found that severe chondral damage with microfracture did not lengthen the return to sport.

RELATIONSHIP BETWEEN INGUINAL-RELATED GROIN PAIN AND FEMOROACETABULAR IMPINGEMENT

The altered biomechanics and restricted range of motion in athletes with FAI cause an increase in compensatory motion at the pelvis and lumbosacral areas, which may contribute to the development of inguinal-related groin pain, bursitis, adductor, and gluteal dysfunction.²⁵ In athletes with concurrent intra-articular hip pathology and inguinal-related groin pain, treating 1 condition in isolation will result in poor results. Larson and colleagues⁶¹ found that when only inguinal-related groin pain or FAI were addressed, return to sport was only 25% and 50%, respectively, while concurrent surgical treatment resulted in a return to sport of 89%.

DISCUSSION AND FUTURE DIRECTIONS

Groin injuries in soccer players can cause significant decreases in athletic performance, result in lost playing time, and may ultimately need a surgical intervention. Efforts are underway to determine the role and efficacy of identifying high-risk athletes that may benefit from targeted prevention strategies. Wyles and colleagues⁴⁸ identified adolescent athletes with hip internal rotation of <10° and found at 5-year follow-up that 95% had abnormal MRI findings compared with 54% in the age-matched control group. Wollin and colleagues⁶² developed an in-season screening protocol using adductor strength reductions of 15%, adductor/abductor strength ratio <0.9, and hip and groin outcome scores <75 as indicators of at-risk individuals. By employing preseason and in-season screening protocols, we can identify high-risk athletes for further workup and close follow-up throughout the season. Pelvic radiographs in these high-risk athletes may help us determine the presence of abnormalities in hip morphology, which would place an athlete into a high-risk group where prevention strategies could then be employed. There are no data available to determine the most effective prevention strategy at this time. However, levels II and III evidence exists indicating that exercise programs may reduce the incidence of groin injuries.⁶³ Additional strategies, like limiting adolescent playing time similar to strategies employed in baseball pitches with pitch counts, could potentially reduce the potential for injury. Further studies on preseason screening and in-season monitoring protocols, targeted exercise therapy, early surgical intervention, and potential biologic intervention are needed to determine the most effective methods of preventing groin injuries in athletes.

Hip and groin injuries in soccer players can be separated into 3 main categories based on the Doha Agreement:⁶ (1) defined clinical entities for groin pain, (2) hip-related groin pain, and (3) other causes of groin pain in athletes. Defined clinical entities include adductor-related, iliopsoas-related, inguinal-related (sports hernia/athletic pubalgia), and pubic-related groin pain; while hip-related groin pain includes hip morphologic abnormalities, labral tears, and chondral injuries. Included in other causes of groin pain are injuries not clinically defined. The Doha Agreement has acknowledged that not all causes of groin pain fit into the classification system including injuries of the rectus femoris, but they will be included under defined clinical entities for groin pain in this review. While they are not a cause of groin pain, proximal hamstring and gluteal and piriformis injuries are important causes of posterior and lateral hip pain in soccer players and will also be covered in the first section of this review.

DEFINED CLINICAL ENTITIES FOR GROIN PAIN IN SOCCER ATHLETES

ADDUCTOR-RELATED GROIN PAIN

Acute groin pain in soccer players is most commonly caused by muscle strain.⁷ Of the muscle strains, 66% involve the adductor longus, 25% the iliopsoas, and 23% the rectus femoris.⁷ The Doha Agreement defines adductor-related groin pain as adductor tenderness and pain on resisted adduction.⁶ Adductor longus strains in soccer players are typically noncontact injuries (62.5%) and most commonly the result of kicking (40%).^7-9 Many athletes will remember a pop at the time of the original injury.⁹ The combination of history and physical examination is usually sufficient for diagnosis; however, magnetic resonance imaging (MRI) may be helpful in complicated situations with a reported 86% sensitivity and 89% specificity.¹⁰ The average playing time lost is 2 weeks.⁵ Management includes rest, anti-inflammatory medication, physical therapy with core strengthening, and avoidance of aggressive stretching. While partial and distal avulsions can heal with conservative measures, proximal osseous and retracted avulsions of the adductor longus can be treated surgically.¹¹

Continue to: ILIOPSOAS-RELATED GROIN PAIN...

Iliopsoas strains account for 25% of acute groin strains and typically result from an impact that causes eccentric overload while kicking the ball.^7,12 Iliopsoas-related groin pain is defined by the Doha Agreement as groin pain that is reproducible with resisted hip flexion or hip flexor stretch.⁶ Iliopsoas strains respond well to conservative treatment such as rest, anti-inflammatory medication, and physical therapy. Rarely do these athletes become surgical candidates in the acute setting. Chronic cases of iliopsoas pathology occasionally require an arthroscopic intervention.

INGUINAL-RELATED GROIN PAIN

Inguinal-related groin pain is one of the most misleading diagnoses in sports because of its poorly defined and under-researched nature. The varying nomenclature of this entity illustrates the heterogeneity and includes sports hernia,^9,13-15 athletic pubalgia,¹⁶ core muscle injury,¹⁷ athletic hernia,¹⁸ Gilmore’s groin,¹⁵ osteitis pubis,¹⁹ sportsman’s hernia,^20,21 sportsmen’s groin,²² symphysis syndrome,²³ and inguinal disruption.²⁴ It is important to realize that in inguinal-related groin pain, regardless of the nomenclature, there is no true hernia present. The Doha Agreement has defined inguinal-related groin pain as “pain in the location of the inguinal region with associated tenderness of the inguinal canal,” which “is more likely if the pain is aggravated with resistance testing of the abdominal muscles or on Valsalva/cough/sneeze.”⁶ The condition is a painful soft tissue injury in the groin or inguinal area, involving a constellation of various anatomic areas including the abdominal musculature, sacroiliac joint, neural structures, pubic symphysis, adductors, and hip joint. This may account for up to 50% of chronic groin pain.^25,26

One important theory in the development of inguinal-related groin pain is its relationship with femoroacetabular impingement (FAI). Cadaver studies demonstrate that cam deformities cause a 35% increase in motion at the pubic symphysis altering the biomechanics of the adductors and abdominal musculature and, with repetitive stress, may lead to tearing or attenuation of the transversalis fascia, rectus abdominis, internal obliques, and/or external obliques.^12,27,28 Another prevailing theory of this is that the increased pubic stress causes weakness in the posterior portion of the inguinal canal, which then stretches and entraps the genitofemoral, ilioinguinal, lateral femoral cutaneous, or obturator nerves, ultimately causing pain.^28,29

Physical examination findings include pain over the conjoined tendon, pubic tubercle/symphysis (present in 22% of patients), adductor origin (36%), and inguinal ring.^25,30 Pain with resisted sit-ups is present in 46% of patients and pain with coughing/Valsalva is present in 10%.^25,30,31 Selective injections can be a critical part of the evaluation to differentiate inguinal-related groin pain from FAI, osteitis pubis, and adductor strains while helping to determine the appropriate treatment.^25,32 The role of advanced imaging is unclear as the clinical entity is still uncertain and the standard imaging findings have not been definitively established.³³ However, several studies have reported MRI findings suggestive of inguinal-related groin pain. One of the more common MRI findings is the “secondary cleft sign,” which requires injecting a dye into the pubic symphysis.³⁴ Several studies have shown that the radiographic dye extravasates preferentially into the side where the groin symptoms exist and are thought to be secondary to micro-tearing at the common attachment of the musculotendinous structures to the anterior pubis.^34,35 However, it should be noted that the lack of imaging findings does not exclude the possibility of inguinal-related groin pathology.

Initial treatment consists of rest, anti-inflammatory medication, injections, and physical therapy with core strengthening.²⁵ A study by Paajanen and colleagues³⁶ suggested that early surgical intervention may be preferred over conservative management in a randomized trial comparing physical therapy, injections, anti-inflammatory medication, and rest vs an extraperitoneal laparoscopic mesh repair behind the pubic symphysis. In the conservative group, 20% of athletes returned to sport at 1 month, 27% at 3 months, and 50% at 12 months.³⁶ In comparison, the surgical group had 67% return to sport at 1 month, 90% at 3 months, and 97% at 12 months.³⁶ If surgical management is chosen, there are a variety of surgical options including laparoscopy, open or mini-open repairs of the abdominal musculature/fascia or pelvic floor with and without mesh, neurolysis, and adductor release. Muschawek and Berger³⁷described a series of 129 patients that had an open-suture repair of the posterior wall of the inguinal canal with 67% of professional athletes returning to sport within 2 weeks and 83.7% of athletes returning to sport overall. The rates of return to play are consistently 80% to 100% without demonstrated superiority of one technique over another up to this point.³⁰

Continue to: PUBIC-RELATED GROIN PAIN...

Pubic-related groin pain is defined as tenderness to palpation over the pubic symphysis and adjacent bone.⁶ Osteitis pubis is a chronic overuse injury characterized by localized pain to the pubic symphysis and is believed to be caused by repetitive microtrauma from a dynamic rotation of the sacroiliac joint with suggested imbalances between the rectus abdominis and the adductor musculature.^12,38 In soccer players, the condition may be related to the constant torsional stresses of kicking, running, or twisting.¹² If performed, radiographs often show lytic areas of the pubic symphysis, widening of the symphysis, sclerosis, and cystic changes, while bone marrow edema may be present on MRI.³⁸Management consists of rest, anti-inflammatory medication, and corticosteroid injections with gentle stretching once asymptomatic.^12,39

RECTUS FEMORIS INJURIES

The most common injury to the rectus femoris is a strain as a result of an eccentric overload while a soccer player is hit trying to extend his or her leg to kick a ball.¹² In pediatric soccer athletes, an avulsion of the anterior inferior iliac spine from the direct head of the rectus femoris is the second most common avulsion injury.⁴⁰ Radiographs are diagnostic and can help determine treatment. Most avulsions are minimally displaced and can be treated conservatively, but surgical intervention should be considered for an avulsion >2 cm.¹²

PROXIMAL HAMSTRING INJURIES

Proximal hamstring injuries are important causes of acute posterior hip pain and are caused by an eccentric overload in hip flexion and knee extension.²⁵ In soccer players, the typical mechanism is that the planted leg slipping on the playing turf creates a sudden violent flexion of the hip with the knee in an extended position. While relatively uncommon, when a significant avulsion occurs in a professional athlete, surgical intervention is often necessary. In general, these injuries may involve partial or full avulsions off the ischial tuberosity or separation of the bony apophysis in pediatric athletes. A physical examination in the acute setting typically demonstrates massive posterior thigh ecchymosis, a palpable defect, and/or weakness with knee flexion. Imaging is helpful to confirm the diagnosis and evaluate for surgical repair. Radiographs may show a bony avulsion, which is more commonly seen in pediatric apophyseal avulsions. MRI can be used to differentiate a complete tear (involving all 3 tendons) vs a partial tear and evaluate for retraction of the tendon distally. Complete and partial tears of 2 tendons with retraction of >2 cm should be surgically repaired.²⁵ Partial tears without tendon retraction may be treated conservatively with rest, anti-inflammatory medication, and physical therapy and then followed later by a hamstring prevention program.²⁵ We have found that biologic augmentation with platelet-rich plasma can help accelerate healing in partial thickness injuries; however, the evidence is conflicting.

GLUTEAL INJURIES

Chronic overuse injuries of the gluteal musculature are common causes of lateral hip pain. Abductor overuse caused by weakness in the gluteus medius with a normal tensor fascia lata can cause pain with sitting and side-lying.²⁵Overuse of the gluteal muscles with muscular imbalances along with increased tension on the iliotibial band can lead to greater trochanteric pain syndrome.²⁵ A physical examination may demonstrate tenderness over the greater trochanter bursa and positive flexion, abduction, and external rotation testing.²⁵ Abductor overuse syndrome and greater trochanteric pain syndrome are best treated with anti-inflammatory medication and physical therapy to balance the core/pelvic musculature.⁴¹

PIRIFORMIS INJURIES

Piriformis syndrome is a compressive neuropathy of the sciatic nerve. The mechanism of injury in the athlete is through a minor trauma to the buttock or pelvis.^25,42,43 Presenting symptoms include pain with sitting and internal rotation of the hip.¹² Zeren and colleagues⁴² published the only study that includes 2 cases of bilateral piriformis syndrome in professional soccer players. The diagnosis was confirmed with electromyography that was negative at rest and positive when measured after running.⁴² The athletes exhausted conservative treatment with physical therapy, anti-inflammatory medications, injections, and rest and were treated with surgical decompression.⁴² Both players returned to professional soccer after 6 months and played for an average of 7 years.⁴²

Continue to: HIP-RELATED GROIN PAIN IN SOCCER ATHLETES...

HIP-RELATED GROIN PAIN IN SOCCER ATHLETES

Hip-related groin pain has garnered more attention in the last several years after being a previously underdiagnosed entity. One study found that practitioners treated groin pain in athletes for 7 months on average before recognizing that the pathology was intra-articular.⁴⁴ FAI, labral tears, and chondral injuries are the major intra-articular pathologies that cause groin pain in athletes and ultimately impaired performance.^45,46

FEMOROACETABULAR IMPINGEMENT

FAI is caused by pincer-type, cam-type, or combined-type deformities. Pincer lesions are defined as an increased acetabular overhang, while cam lesions are described as an increased bone at the femoral head/neck junction. These deformities in isolation or in combination cause decreased hip motion and increased contact pressures between the anterolateral acetabulum and femoral head-neck junction, which may ultimately lead to labral tears, chondral lesions, and osteoarthritis.⁴⁷ During hip flexion, cam deformities impact the anterolateral acetabulum, preferentially causing articular cartilage damage, while sparing the labrum.²⁵ Conversely, pincer deformities cause repetitive microtrauma to the labrum, crushing it between the acetabular rim and femoral neck with secondary damage to the articular cartilage.²⁵ Over time, the damage to the labrum and articular cartilage may lead to premature osteoarthritis, which occurs at a much younger age in the athletic population.⁴⁸

We know from previous studies that soccer athletes have a high prevalence of morphologic abnormalities of the hip, most commonly FAI. Gerhardt and colleagues⁴⁹ documented the prevalence of hip morphologic abnormalities in elite soccer players and found abnormalities in 72% of men and over 50% of women. It should be noted that this series looked at asymptomatic athletes; however, it has been shown that hip dysmorphia is a risk factor for hip and groin injuries and may provide an opportunity for injury prevention strategies.⁵⁰

Physical examination findings in FAI include decreased hip internal rotation and pain with provocative testing. Wyss and colleagues⁵¹ measured hip internal rotation in athletes with and without FAI. They found that the athletes with FAI have an average of 4° of internal rotation compared with that of the non-FAI athletes with 28°.⁵¹ A worsening internal rotation deficit has been linked to increasing severity of the deformity and when <20° was correlated with joint damage.⁵¹ Provocative testing has a high sensitivity with a recent meta-analysis demonstrating the most sensitive tests to be the anterior impingement test (flexion-adduction-internal rotation) with 94% to 99% sensitivity and the flexion-internal rotation test with 96% sensitivity.⁵² While provocative tests are sensitive, there is no current consensus on physical examination findings that are specific in the diagnosis of FAI.⁶ Diagnosis is made with both positive physical examination and radiographic morphologic findings (alpha angle >55°).³³ Advanced imaging with an MRI arthrogram can be helpful in diagnosing underlying injuries such as labral tears in athletes presenting with compatible symptoms.

Symptomatic patients are typically treated surgically through either open or arthroscopic procedures, which have favorable and comparable functional results, biomechanics, and return to sport.⁵³ In soccer players, return to sport at the professional level after arthroscopic surgery was found to be 96%.⁵⁴ Players returned to sport on average 9.2 months postoperatively and played an average of 70 games after surgery.⁵⁴

Continue to: LABRAL TEARS...

Labral tears present with groin pain, limited hip range of motion, and symptoms of catching, locking, and instability.²⁵Causes of labral tears include trauma, FAI, hip dysplasia, capsular laxity, and degeneration.⁵⁵ Labral tears rarely occur in isolation and have a high association (87%) with morphologic abnormalities of the hip, most commonly FAI and occasionally dysplasia.^56,57 Physical examination findings include positive anterior impingement tests (flexion-adduction-internal rotation) in athletes with anterior labral tears and, less commonly, positive flexion, abduction, and external rotation tests for athletes with lateral and posterolateral labral tears.⁵⁷ Radiographic imaging is used to evaluate for concurrent morphologic abnormalities of the hip, and MRI arthrogram is used to confirm the diagnosis of a labral tear with a sensitivity of 76% to 91%.⁵⁸ Initial treatment consists of conservative treatment, which includes rest, anti-inflammatory medication, activity modification, and physical therapy. In patient refractory to conservative treatment, arthroscopic surgery is effective with high rates of return to sport.⁵⁹ It is important to note that when treating labral tears surgically, any morphologic abnormality needs to be addressed to prevent recurrence of the tear.

CHONDRAL INJURIES

Focal chondral lesions in the hip are commonly found in athletes with FAI and labral tears during arthroscopic evaluation.⁶⁰ Full-thickness defects and unstable flaps in weight-bearing areas are indications for surgical intervention with microfracture.⁶⁰ There are no studies examining the efficacy of microfracture in isolation; however, Locks and colleagues⁵⁴ have demonstrated a 96% return to professional soccer after an arthroscopic treatment for FAI and found that severe chondral damage with microfracture did not lengthen the return to sport.

RELATIONSHIP BETWEEN INGUINAL-RELATED GROIN PAIN AND FEMOROACETABULAR IMPINGEMENT

The altered biomechanics and restricted range of motion in athletes with FAI cause an increase in compensatory motion at the pelvis and lumbosacral areas, which may contribute to the development of inguinal-related groin pain, bursitis, adductor, and gluteal dysfunction.²⁵ In athletes with concurrent intra-articular hip pathology and inguinal-related groin pain, treating 1 condition in isolation will result in poor results. Larson and colleagues⁶¹ found that when only inguinal-related groin pain or FAI were addressed, return to sport was only 25% and 50%, respectively, while concurrent surgical treatment resulted in a return to sport of 89%.

DISCUSSION AND FUTURE DIRECTIONS

Groin injuries in soccer players can cause significant decreases in athletic performance, result in lost playing time, and may ultimately need a surgical intervention. Efforts are underway to determine the role and efficacy of identifying high-risk athletes that may benefit from targeted prevention strategies. Wyles and colleagues⁴⁸ identified adolescent athletes with hip internal rotation of <10° and found at 5-year follow-up that 95% had abnormal MRI findings compared with 54% in the age-matched control group. Wollin and colleagues⁶² developed an in-season screening protocol using adductor strength reductions of 15%, adductor/abductor strength ratio <0.9, and hip and groin outcome scores <75 as indicators of at-risk individuals. By employing preseason and in-season screening protocols, we can identify high-risk athletes for further workup and close follow-up throughout the season. Pelvic radiographs in these high-risk athletes may help us determine the presence of abnormalities in hip morphology, which would place an athlete into a high-risk group where prevention strategies could then be employed. There are no data available to determine the most effective prevention strategy at this time. However, levels II and III evidence exists indicating that exercise programs may reduce the incidence of groin injuries.⁶³ Additional strategies, like limiting adolescent playing time similar to strategies employed in baseball pitches with pitch counts, could potentially reduce the potential for injury. Further studies on preseason screening and in-season monitoring protocols, targeted exercise therapy, early surgical intervention, and potential biologic intervention are needed to determine the most effective methods of preventing groin injuries in athletes.

Hip and groin injuries in soccer players can be separated into 3 main categories based on the Doha Agreement:⁶ (1) defined clinical entities for groin pain, (2) hip-related groin pain, and (3) other causes of groin pain in athletes. Defined clinical entities include adductor-related, iliopsoas-related, inguinal-related (sports hernia/athletic pubalgia), and pubic-related groin pain; while hip-related groin pain includes hip morphologic abnormalities, labral tears, and chondral injuries. Included in other causes of groin pain are injuries not clinically defined. The Doha Agreement has acknowledged that not all causes of groin pain fit into the classification system including injuries of the rectus femoris, but they will be included under defined clinical entities for groin pain in this review. While they are not a cause of groin pain, proximal hamstring and gluteal and piriformis injuries are important causes of posterior and lateral hip pain in soccer players and will also be covered in the first section of this review.

DEFINED CLINICAL ENTITIES FOR GROIN PAIN IN SOCCER ATHLETES

ADDUCTOR-RELATED GROIN PAIN

Acute groin pain in soccer players is most commonly caused by muscle strain.⁷ Of the muscle strains, 66% involve the adductor longus, 25% the iliopsoas, and 23% the rectus femoris.⁷ The Doha Agreement defines adductor-related groin pain as adductor tenderness and pain on resisted adduction.⁶ Adductor longus strains in soccer players are typically noncontact injuries (62.5%) and most commonly the result of kicking (40%).^7-9 Many athletes will remember a pop at the time of the original injury.⁹ The combination of history and physical examination is usually sufficient for diagnosis; however, magnetic resonance imaging (MRI) may be helpful in complicated situations with a reported 86% sensitivity and 89% specificity.¹⁰ The average playing time lost is 2 weeks.⁵ Management includes rest, anti-inflammatory medication, physical therapy with core strengthening, and avoidance of aggressive stretching. While partial and distal avulsions can heal with conservative measures, proximal osseous and retracted avulsions of the adductor longus can be treated surgically.¹¹

Continue to: ILIOPSOAS-RELATED GROIN PAIN...

Iliopsoas strains account for 25% of acute groin strains and typically result from an impact that causes eccentric overload while kicking the ball.^7,12 Iliopsoas-related groin pain is defined by the Doha Agreement as groin pain that is reproducible with resisted hip flexion or hip flexor stretch.⁶ Iliopsoas strains respond well to conservative treatment such as rest, anti-inflammatory medication, and physical therapy. Rarely do these athletes become surgical candidates in the acute setting. Chronic cases of iliopsoas pathology occasionally require an arthroscopic intervention.

INGUINAL-RELATED GROIN PAIN

Inguinal-related groin pain is one of the most misleading diagnoses in sports because of its poorly defined and under-researched nature. The varying nomenclature of this entity illustrates the heterogeneity and includes sports hernia,^9,13-15 athletic pubalgia,¹⁶ core muscle injury,¹⁷ athletic hernia,¹⁸ Gilmore’s groin,¹⁵ osteitis pubis,¹⁹ sportsman’s hernia,^20,21 sportsmen’s groin,²² symphysis syndrome,²³ and inguinal disruption.²⁴ It is important to realize that in inguinal-related groin pain, regardless of the nomenclature, there is no true hernia present. The Doha Agreement has defined inguinal-related groin pain as “pain in the location of the inguinal region with associated tenderness of the inguinal canal,” which “is more likely if the pain is aggravated with resistance testing of the abdominal muscles or on Valsalva/cough/sneeze.”⁶ The condition is a painful soft tissue injury in the groin or inguinal area, involving a constellation of various anatomic areas including the abdominal musculature, sacroiliac joint, neural structures, pubic symphysis, adductors, and hip joint. This may account for up to 50% of chronic groin pain.^25,26

One important theory in the development of inguinal-related groin pain is its relationship with femoroacetabular impingement (FAI). Cadaver studies demonstrate that cam deformities cause a 35% increase in motion at the pubic symphysis altering the biomechanics of the adductors and abdominal musculature and, with repetitive stress, may lead to tearing or attenuation of the transversalis fascia, rectus abdominis, internal obliques, and/or external obliques.^12,27,28 Another prevailing theory of this is that the increased pubic stress causes weakness in the posterior portion of the inguinal canal, which then stretches and entraps the genitofemoral, ilioinguinal, lateral femoral cutaneous, or obturator nerves, ultimately causing pain.^28,29

Physical examination findings include pain over the conjoined tendon, pubic tubercle/symphysis (present in 22% of patients), adductor origin (36%), and inguinal ring.^25,30 Pain with resisted sit-ups is present in 46% of patients and pain with coughing/Valsalva is present in 10%.^25,30,31 Selective injections can be a critical part of the evaluation to differentiate inguinal-related groin pain from FAI, osteitis pubis, and adductor strains while helping to determine the appropriate treatment.^25,32 The role of advanced imaging is unclear as the clinical entity is still uncertain and the standard imaging findings have not been definitively established.³³ However, several studies have reported MRI findings suggestive of inguinal-related groin pain. One of the more common MRI findings is the “secondary cleft sign,” which requires injecting a dye into the pubic symphysis.³⁴ Several studies have shown that the radiographic dye extravasates preferentially into the side where the groin symptoms exist and are thought to be secondary to micro-tearing at the common attachment of the musculotendinous structures to the anterior pubis.^34,35 However, it should be noted that the lack of imaging findings does not exclude the possibility of inguinal-related groin pathology.

Initial treatment consists of rest, anti-inflammatory medication, injections, and physical therapy with core strengthening.²⁵ A study by Paajanen and colleagues³⁶ suggested that early surgical intervention may be preferred over conservative management in a randomized trial comparing physical therapy, injections, anti-inflammatory medication, and rest vs an extraperitoneal laparoscopic mesh repair behind the pubic symphysis. In the conservative group, 20% of athletes returned to sport at 1 month, 27% at 3 months, and 50% at 12 months.³⁶ In comparison, the surgical group had 67% return to sport at 1 month, 90% at 3 months, and 97% at 12 months.³⁶ If surgical management is chosen, there are a variety of surgical options including laparoscopy, open or mini-open repairs of the abdominal musculature/fascia or pelvic floor with and without mesh, neurolysis, and adductor release. Muschawek and Berger³⁷described a series of 129 patients that had an open-suture repair of the posterior wall of the inguinal canal with 67% of professional athletes returning to sport within 2 weeks and 83.7% of athletes returning to sport overall. The rates of return to play are consistently 80% to 100% without demonstrated superiority of one technique over another up to this point.³⁰

Continue to: PUBIC-RELATED GROIN PAIN...

Pubic-related groin pain is defined as tenderness to palpation over the pubic symphysis and adjacent bone.⁶ Osteitis pubis is a chronic overuse injury characterized by localized pain to the pubic symphysis and is believed to be caused by repetitive microtrauma from a dynamic rotation of the sacroiliac joint with suggested imbalances between the rectus abdominis and the adductor musculature.^12,38 In soccer players, the condition may be related to the constant torsional stresses of kicking, running, or twisting.¹² If performed, radiographs often show lytic areas of the pubic symphysis, widening of the symphysis, sclerosis, and cystic changes, while bone marrow edema may be present on MRI.³⁸Management consists of rest, anti-inflammatory medication, and corticosteroid injections with gentle stretching once asymptomatic.^12,39

RECTUS FEMORIS INJURIES

The most common injury to the rectus femoris is a strain as a result of an eccentric overload while a soccer player is hit trying to extend his or her leg to kick a ball.¹² In pediatric soccer athletes, an avulsion of the anterior inferior iliac spine from the direct head of the rectus femoris is the second most common avulsion injury.⁴⁰ Radiographs are diagnostic and can help determine treatment. Most avulsions are minimally displaced and can be treated conservatively, but surgical intervention should be considered for an avulsion >2 cm.¹²

PROXIMAL HAMSTRING INJURIES

Proximal hamstring injuries are important causes of acute posterior hip pain and are caused by an eccentric overload in hip flexion and knee extension.²⁵ In soccer players, the typical mechanism is that the planted leg slipping on the playing turf creates a sudden violent flexion of the hip with the knee in an extended position. While relatively uncommon, when a significant avulsion occurs in a professional athlete, surgical intervention is often necessary. In general, these injuries may involve partial or full avulsions off the ischial tuberosity or separation of the bony apophysis in pediatric athletes. A physical examination in the acute setting typically demonstrates massive posterior thigh ecchymosis, a palpable defect, and/or weakness with knee flexion. Imaging is helpful to confirm the diagnosis and evaluate for surgical repair. Radiographs may show a bony avulsion, which is more commonly seen in pediatric apophyseal avulsions. MRI can be used to differentiate a complete tear (involving all 3 tendons) vs a partial tear and evaluate for retraction of the tendon distally. Complete and partial tears of 2 tendons with retraction of >2 cm should be surgically repaired.²⁵ Partial tears without tendon retraction may be treated conservatively with rest, anti-inflammatory medication, and physical therapy and then followed later by a hamstring prevention program.²⁵ We have found that biologic augmentation with platelet-rich plasma can help accelerate healing in partial thickness injuries; however, the evidence is conflicting.

GLUTEAL INJURIES

Chronic overuse injuries of the gluteal musculature are common causes of lateral hip pain. Abductor overuse caused by weakness in the gluteus medius with a normal tensor fascia lata can cause pain with sitting and side-lying.²⁵Overuse of the gluteal muscles with muscular imbalances along with increased tension on the iliotibial band can lead to greater trochanteric pain syndrome.²⁵ A physical examination may demonstrate tenderness over the greater trochanter bursa and positive flexion, abduction, and external rotation testing.²⁵ Abductor overuse syndrome and greater trochanteric pain syndrome are best treated with anti-inflammatory medication and physical therapy to balance the core/pelvic musculature.⁴¹

PIRIFORMIS INJURIES

Piriformis syndrome is a compressive neuropathy of the sciatic nerve. The mechanism of injury in the athlete is through a minor trauma to the buttock or pelvis.^25,42,43 Presenting symptoms include pain with sitting and internal rotation of the hip.¹² Zeren and colleagues⁴² published the only study that includes 2 cases of bilateral piriformis syndrome in professional soccer players. The diagnosis was confirmed with electromyography that was negative at rest and positive when measured after running.⁴² The athletes exhausted conservative treatment with physical therapy, anti-inflammatory medications, injections, and rest and were treated with surgical decompression.⁴² Both players returned to professional soccer after 6 months and played for an average of 7 years.⁴²

Continue to: HIP-RELATED GROIN PAIN IN SOCCER ATHLETES...

HIP-RELATED GROIN PAIN IN SOCCER ATHLETES

Hip-related groin pain has garnered more attention in the last several years after being a previously underdiagnosed entity. One study found that practitioners treated groin pain in athletes for 7 months on average before recognizing that the pathology was intra-articular.⁴⁴ FAI, labral tears, and chondral injuries are the major intra-articular pathologies that cause groin pain in athletes and ultimately impaired performance.^45,46

FEMOROACETABULAR IMPINGEMENT

FAI is caused by pincer-type, cam-type, or combined-type deformities. Pincer lesions are defined as an increased acetabular overhang, while cam lesions are described as an increased bone at the femoral head/neck junction. These deformities in isolation or in combination cause decreased hip motion and increased contact pressures between the anterolateral acetabulum and femoral head-neck junction, which may ultimately lead to labral tears, chondral lesions, and osteoarthritis.⁴⁷ During hip flexion, cam deformities impact the anterolateral acetabulum, preferentially causing articular cartilage damage, while sparing the labrum.²⁵ Conversely, pincer deformities cause repetitive microtrauma to the labrum, crushing it between the acetabular rim and femoral neck with secondary damage to the articular cartilage.²⁵ Over time, the damage to the labrum and articular cartilage may lead to premature osteoarthritis, which occurs at a much younger age in the athletic population.⁴⁸

We know from previous studies that soccer athletes have a high prevalence of morphologic abnormalities of the hip, most commonly FAI. Gerhardt and colleagues⁴⁹ documented the prevalence of hip morphologic abnormalities in elite soccer players and found abnormalities in 72% of men and over 50% of women. It should be noted that this series looked at asymptomatic athletes; however, it has been shown that hip dysmorphia is a risk factor for hip and groin injuries and may provide an opportunity for injury prevention strategies.⁵⁰

Physical examination findings in FAI include decreased hip internal rotation and pain with provocative testing. Wyss and colleagues⁵¹ measured hip internal rotation in athletes with and without FAI. They found that the athletes with FAI have an average of 4° of internal rotation compared with that of the non-FAI athletes with 28°.⁵¹ A worsening internal rotation deficit has been linked to increasing severity of the deformity and when <20° was correlated with joint damage.⁵¹ Provocative testing has a high sensitivity with a recent meta-analysis demonstrating the most sensitive tests to be the anterior impingement test (flexion-adduction-internal rotation) with 94% to 99% sensitivity and the flexion-internal rotation test with 96% sensitivity.⁵² While provocative tests are sensitive, there is no current consensus on physical examination findings that are specific in the diagnosis of FAI.⁶ Diagnosis is made with both positive physical examination and radiographic morphologic findings (alpha angle >55°).³³ Advanced imaging with an MRI arthrogram can be helpful in diagnosing underlying injuries such as labral tears in athletes presenting with compatible symptoms.

Symptomatic patients are typically treated surgically through either open or arthroscopic procedures, which have favorable and comparable functional results, biomechanics, and return to sport.⁵³ In soccer players, return to sport at the professional level after arthroscopic surgery was found to be 96%.⁵⁴ Players returned to sport on average 9.2 months postoperatively and played an average of 70 games after surgery.⁵⁴

Continue to: LABRAL TEARS...

Labral tears present with groin pain, limited hip range of motion, and symptoms of catching, locking, and instability.²⁵Causes of labral tears include trauma, FAI, hip dysplasia, capsular laxity, and degeneration.⁵⁵ Labral tears rarely occur in isolation and have a high association (87%) with morphologic abnormalities of the hip, most commonly FAI and occasionally dysplasia.^56,57 Physical examination findings include positive anterior impingement tests (flexion-adduction-internal rotation) in athletes with anterior labral tears and, less commonly, positive flexion, abduction, and external rotation tests for athletes with lateral and posterolateral labral tears.⁵⁷ Radiographic imaging is used to evaluate for concurrent morphologic abnormalities of the hip, and MRI arthrogram is used to confirm the diagnosis of a labral tear with a sensitivity of 76% to 91%.⁵⁸ Initial treatment consists of conservative treatment, which includes rest, anti-inflammatory medication, activity modification, and physical therapy. In patient refractory to conservative treatment, arthroscopic surgery is effective with high rates of return to sport.⁵⁹ It is important to note that when treating labral tears surgically, any morphologic abnormality needs to be addressed to prevent recurrence of the tear.

CHONDRAL INJURIES

Focal chondral lesions in the hip are commonly found in athletes with FAI and labral tears during arthroscopic evaluation.⁶⁰ Full-thickness defects and unstable flaps in weight-bearing areas are indications for surgical intervention with microfracture.⁶⁰ There are no studies examining the efficacy of microfracture in isolation; however, Locks and colleagues⁵⁴ have demonstrated a 96% return to professional soccer after an arthroscopic treatment for FAI and found that severe chondral damage with microfracture did not lengthen the return to sport.

RELATIONSHIP BETWEEN INGUINAL-RELATED GROIN PAIN AND FEMOROACETABULAR IMPINGEMENT

The altered biomechanics and restricted range of motion in athletes with FAI cause an increase in compensatory motion at the pelvis and lumbosacral areas, which may contribute to the development of inguinal-related groin pain, bursitis, adductor, and gluteal dysfunction.²⁵ In athletes with concurrent intra-articular hip pathology and inguinal-related groin pain, treating 1 condition in isolation will result in poor results. Larson and colleagues⁶¹ found that when only inguinal-related groin pain or FAI were addressed, return to sport was only 25% and 50%, respectively, while concurrent surgical treatment resulted in a return to sport of 89%.

DISCUSSION AND FUTURE DIRECTIONS

Groin injuries in soccer players can cause significant decreases in athletic performance, result in lost playing time, and may ultimately need a surgical intervention. Efforts are underway to determine the role and efficacy of identifying high-risk athletes that may benefit from targeted prevention strategies. Wyles and colleagues⁴⁸ identified adolescent athletes with hip internal rotation of <10° and found at 5-year follow-up that 95% had abnormal MRI findings compared with 54% in the age-matched control group. Wollin and colleagues⁶² developed an in-season screening protocol using adductor strength reductions of 15%, adductor/abductor strength ratio <0.9, and hip and groin outcome scores <75 as indicators of at-risk individuals. By employing preseason and in-season screening protocols, we can identify high-risk athletes for further workup and close follow-up throughout the season. Pelvic radiographs in these high-risk athletes may help us determine the presence of abnormalities in hip morphology, which would place an athlete into a high-risk group where prevention strategies could then be employed. There are no data available to determine the most effective prevention strategy at this time. However, levels II and III evidence exists indicating that exercise programs may reduce the incidence of groin injuries.⁶³ Additional strategies, like limiting adolescent playing time similar to strategies employed in baseball pitches with pitch counts, could potentially reduce the potential for injury. Further studies on preseason screening and in-season monitoring protocols, targeted exercise therapy, early surgical intervention, and potential biologic intervention are needed to determine the most effective methods of preventing groin injuries in athletes.

Despite these extensive research efforts, there is currently little information in the literature regarding when postoperative adverse events occur. A clear depiction of the timing of adverse events could help target clinical surveillance, inform patient counseling, and determine the duration of follow-up required for studies. The reason that the timing of adverse events has not been previously characterized may be that the sample sizes available through standard single- or multi-institutional studies may be insufficient to accurately characterize the timing of rare adverse events (eg, myocardial infarction, stroke, etc.). Moreover, although administrative datasets have become common data sources for investigation of rare postoperative adverse events,^13-16 such data sources often do not contain data on the timing of diagnosis.

The American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) is a relatively new and growing surgical registry.^1,3,13-22 The registry follows up patients undergoing surgical procedures at several hundred community and academic institutions nationwide. Unlike the administrative datasets discussed above, the ACS-NSQIP characterizes the postoperative day of diagnosis of well-defined adverse events during the first 30 postoperative days.²²

In this study, data collected by the ACS-NSQIP are used to characterize the timing of 10 specific postoperative adverse events following a geriatric hip fracture surgery.

Continue to: METHODS...

METHODS

A retrospective analysis of data collected prospectively through the ACS-NSQIP was conducted. Geriatric patients who underwent hip fracture surgery during 2010 to 2013 were identified. Specific inclusion criteria were (1) International Classification of Diseases, Ninth Revision, diagnosis code 820, (2) primary Current Procedural Terminology codes 27125, 27130, 27235, 27236, 27244, or 27245, and (3) age ≥70 years.

The ACS-NSQIP captures patient demographic, comorbidity, and procedural characteristics at baseline.²² At the end of the 30-day follow-up period, the ACS-NSQIP personnel review both inpatient and outpatient charts to characterize the occurrence vs nonoccurrence of specific postoperative adverse events.^22-25 When an adverse event does occur, the postoperative day of diagnosis is recorded.

For this study, the following adverse event categories were investigated: myocardial infarction, cardiac arrest requiring cardiopulmonary resuscitation, stroke, pneumonia, pulmonary embolism, urinary tract infection, deep vein thrombosis, sepsis (either with or without shock), mortality, and surgical site infection (including superficial surgical site infection, deep surgical site infection, and organ or space surgical site infection). Detailed definitions of each adverse event are provided in ACS-NSQIP materials.²²

First, the 30-day incidence (and the associated 95% confidence interval) was determined for each adverse event. Second, the median postoperative day of diagnosis (and the associated interquartile range) was determined for each adverse event. Third, the postoperative length of stay was used to estimate the proportion of diagnoses occurring prior to vs following discharge for each adverse event. Finally, multivariate Cox proportional hazards models were used to identify independent risk factors for earlier occurrence of postoperative adverse events. The final models were selected using a backward stepwise process that sequentially eliminated variables with the weakest associations until all variables had P < .05.

Because the ACS-NSQIP reports timing data in calendar days, when the postoperative length of stay was equivalent to the postoperative day of diagnosis, it was not possible to ascertain whether the diagnosis occurred prior to or following discharge. For this study, when the postoperative length of stay was equivalent to the postoperative day of diagnosis, the adverse event was considered to have been diagnosed following discharge. The rationale for this is that for most of the adverse events, it was thought to be unlikely that an inpatient would be discharged before the end of the same day as an inpatient diagnosis. However, there was one exception to this rule; when the postoperative day of discharge, the postoperative length of stay, and the postoperative day of death were all equivalent, the adverse event was considered to have occurred prior to discharge. This is because when a patient dies during the initial inpatient stay, the ACS-NSQIP considers the postoperative length of stay to be equivalent to the postoperative day of death. This makes it much more likely that a diagnosis on the final hospital day had occurred in a patient who had not been discharged.

The mandatory ACS-NSQIP statement is “The American College of Surgeons National Surgical Quality Improvement Program and the hospitals participating in the ACS-NSQIP are the source of the data used herein; they have not verified and are not responsible for the statistical validity of the data analysis or the conclusions derived by the authors.”²⁶

Continue to: RESULTS...

RESULTS

In total, 19,873 geriatric patients undergoing a hip fracture surgery were identified (Table 1). The rates of adverse events ranged from 6.7% for urinary tract infection to 0.6% for pulmonary embolism (Table 2).

Table 1. Patient Population

Abbreviation: COPD, chronic obstructive pulmonary disease.

Table 2. Patients with Adverse Events Diagnosed During the First 30 postoperative days (N = 19,873)

Abbreviation: CI, confidence interval.

Figure 1 depicts the timing of postoperative adverse events in detail in histograms and timing curves. For the earliest diagnosed adverse events, the rate of adverse events had diminished by postoperative day 30. For the later diagnosed adverse events, the rate of adverse events remained high at postoperative day 30.

Figure 2 provides the summary statistics for adverse events diagnosed in the first 30 postoperative days. The median postoperative day of diagnosis (and the interquartile range) was 3 (1-5) for myocardial infarction, 3 (0-8) for cardiac arrest requiring cardiopulmonary resuscitation, 3 (1-10) for stroke, 4 (2-10) for pneumonia, 4 (2-11) for pulmonary embolism, 7 (2-13) for urinary tract infection, 9 (4-16) for deep vein thrombosis, 9 (4-18) for sepsis, 11 (6-19) for mortality, and 16 (11-22) for surgical site infection.

Figure 3 depicts the timing of adverse events relative to discharge. The proportions of adverse events diagnosed prior to discharge were 81.0% for myocardial infarction, 77.8% for stroke, 76.1% for cardiac arrest requiring cardiopulmonary resuscitation, 71.9% for pulmonary embolism, 71.1% for pneumonia, 58.0% for urinary tract infection, 52.1% for sepsis, 46.9% for deep vein thrombosis, 44.3% for mortality, and 27.6% for surgical site infection.

Table 3 shows the independent risk factors for earlier occurrence of adverse events. Following multivariate stepwise selection of final models, at least 1 patient characteristic was independently associated with the timing of cardiac arrest, stroke, urinary tract infection, deep vein thrombosis, and death. In contrast, no patient characteristics were independently associated with the timing of myocardial infarction, pneumonia, pulmonary embolism, sepsis, and surgical site infection.

Table 3. Timing of Diagnosis of Adverse Events^a

^aBaseline characteristics that were independently associated with the timing of each adverse event were identified through a backwards stepwise selection process initially including all characteristics listed in Table 1, and sequentially excluding characteristics with the weakest associations until only characteristics with P < .05 remained. Independent associations with the timing of cardiac arrest, stroke, urinary tract infection, deep vein thrombosis, and death are shown. There were no characteristics independently associated with timing of myocardial infarction, pneumonia, pulmonary embolism, sepsis, or surgical site infection; hence, these adverse events are not listed in the table.

^bFrom final Cox proportional hazards models identified through multivariate stepwise selection.

Continue to: DISCUSSION...

DISCUSSION

Adverse events are extremely common following a geriatric hip fracture surgery.^1-4 Despite extensive investigation regarding methods to prevent these events,^5-12 there is limited published description of the timing at which such events occur. This study used a large prospectively followed up cohort of geriatric patients undergoing a hip fracture surgery to deliver a better description of the timing of adverse events than was previously available. The findings of this study should enable more targeted clinical surveillance, inform patient counseling, and help determine the duration of follow-up required for studies on adverse events.

There was wide variability in the timing at which the different postoperative adverse events were diagnosed (Figures 1, 2). Myocardial infarction was diagnosed the earliest, with more than three-fourth of diagnoses in the first postoperative week. Other relatively early-diagnosed adverse events included cardiac arrest requiring cardiopulmonary resuscitation, stroke, pneumonia, and pulmonary embolism.

The latest-diagnosed adverse event was surgical site infection (Figures 1, 2). Surgical site infection was actually the only adverse event with a rate of diagnosis during the first week that was lower than the rate of diagnosis later in the month (as can be seen by the inflection in the timing curve for surgical site infection in Figure 1). Mortality showed a relatively consistent rate of diagnosis throughout the entire first postoperative month. Other relatively late-diagnosed postoperative events, including sepsis, deep vein thrombosis, and urinary tract infection, showed varying degrees of decreased rate of diagnosis near the end of the first postoperative month. Of note, for the later-diagnosed adverse events, the estimated median and interquartile ranges (Figure 2) were presumably quite biased toward earlier diagnosis, as the 30-day follow-up period clearly failed to capture a large proportion of later-occurring adverse events (Figure 1).

Certain risk factors were independently associated with earlier occurrence of adverse events. Perhaps most strikingly, body mass index in the obese range was associated with substantially earlier occurrence of deep vein thrombosis (median of 5 vs 10 days). This finding suggests that clinical monitoring for deep vein thrombosis should be performed earlier in patients with greater body mass index. Also notable is the earlier occurrence of cardiac arrest and death among patients with end-stage renal disease than among those without. Patients with end-stage renal disease may have a greater risk for these adverse events immediately following the cardiac stresses of surgery.²⁷ Similarly, such patients may be more prone to early electrolyte abnormalities and arrhythmia.

Continue to: In addition to its clinical implications, this study...

In addition to its clinical implications, this study informs about the interpretation of the many studies of adverse events following hip fracture procedures that have been conducted using retrospective data. Several such studies have relied on inpatient-only administrative databases.^{4,13,14,28-35} As clearly demonstrated in Figure 3, for most of the commonly studied adverse events, inpatient-only databases failed to capture a large proportion of adverse events occurring in the first postoperative month. This highlights a substantial limitation of this commonly published type of study that is often not emphasized in the literature.

There has also been an increase in the publication of studies of adverse events following a hip fracture surgery using the ACS-NSQIP data.^{3,13,14,17,18,21} As discussed, the ACS-NSQIP provides data on 30-days of follow-up. This relatively extended follow-up is often touted as a distinct advantage. However, this study demonstrates that even the 30-day follow-up afforded by the ACS-NSQIP is limited in its ability to enable investigation of the later-occurring adverse events (Figure 1). In particular, the rate of surgical site infection shows little sign of slowing by postoperative day 30. Similarly, the rates of mortality, sepsis, deep vein thrombosis, and urinary tract infection remain substantial.

This study does have limitations. First, as discussed, the duration of follow-up is a limitation of any ACS-NSQIP-based investigation, including this study. Second, the ACS-NSQIP does not capture relevant orthopedic-specific outcomes (eg, screw cutout). In addition, it could not be determined with certainty whether adverse events occurring on the final hospital day occurred prior to or following discharge. However, only a small proportion of most of the adverse events was diagnosed on the final hospital day. Finally, the ACS-NSQIP reports on days from the operation until diagnosis of the adverse event. Although some adverse events are probably diagnosed quickly after they have occurred (eg, myocardial infarction and cardiac arrest), other adverse events may have a delayed diagnosis (eg, surgical site infection may be identified days after its initial occurrence during a follow-up examination). Therefore, it is important to note the subtle distinction between occurrence and diagnosis throughout the article. This article reports on the timing of diagnosis, not actual occurrence.

CONCLUSION

The timing of postoperative adverse events has been understudied in the past. This may be due to an inability of standard single- or multi-institutional investigations to achieve sample sizes adequate to study the less commonly occurring adverse events. Using a relatively new prospective surgical registry, this study provides a far more detailed description of the timing of adverse events following surgery than was previously available. The authors anticipate that these data can be used to inform patient counseling, target clinical surveillance, and direct clinical research. The authors chose to study the timing of postoperative adverse events following geriatric hip fracture surgery because of the high rate of adverse events associated with the procedure. However, future ACS-NSQIP studies may involve characterization of the timing of adverse events following other orthopedic and non-orthopedic procedures.

This paper will be judged for the Resident Writer’s Award.

Despite these extensive research efforts, there is currently little information in the literature regarding when postoperative adverse events occur. A clear depiction of the timing of adverse events could help target clinical surveillance, inform patient counseling, and determine the duration of follow-up required for studies. The reason that the timing of adverse events has not been previously characterized may be that the sample sizes available through standard single- or multi-institutional studies may be insufficient to accurately characterize the timing of rare adverse events (eg, myocardial infarction, stroke, etc.). Moreover, although administrative datasets have become common data sources for investigation of rare postoperative adverse events,^13-16 such data sources often do not contain data on the timing of diagnosis.

The American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) is a relatively new and growing surgical registry.^1,3,13-22 The registry follows up patients undergoing surgical procedures at several hundred community and academic institutions nationwide. Unlike the administrative datasets discussed above, the ACS-NSQIP characterizes the postoperative day of diagnosis of well-defined adverse events during the first 30 postoperative days.²²

In this study, data collected by the ACS-NSQIP are used to characterize the timing of 10 specific postoperative adverse events following a geriatric hip fracture surgery.

Continue to: METHODS...

METHODS

A retrospective analysis of data collected prospectively through the ACS-NSQIP was conducted. Geriatric patients who underwent hip fracture surgery during 2010 to 2013 were identified. Specific inclusion criteria were (1) International Classification of Diseases, Ninth Revision, diagnosis code 820, (2) primary Current Procedural Terminology codes 27125, 27130, 27235, 27236, 27244, or 27245, and (3) age ≥70 years.

The ACS-NSQIP captures patient demographic, comorbidity, and procedural characteristics at baseline.²² At the end of the 30-day follow-up period, the ACS-NSQIP personnel review both inpatient and outpatient charts to characterize the occurrence vs nonoccurrence of specific postoperative adverse events.^22-25 When an adverse event does occur, the postoperative day of diagnosis is recorded.

For this study, the following adverse event categories were investigated: myocardial infarction, cardiac arrest requiring cardiopulmonary resuscitation, stroke, pneumonia, pulmonary embolism, urinary tract infection, deep vein thrombosis, sepsis (either with or without shock), mortality, and surgical site infection (including superficial surgical site infection, deep surgical site infection, and organ or space surgical site infection). Detailed definitions of each adverse event are provided in ACS-NSQIP materials.²²

First, the 30-day incidence (and the associated 95% confidence interval) was determined for each adverse event. Second, the median postoperative day of diagnosis (and the associated interquartile range) was determined for each adverse event. Third, the postoperative length of stay was used to estimate the proportion of diagnoses occurring prior to vs following discharge for each adverse event. Finally, multivariate Cox proportional hazards models were used to identify independent risk factors for earlier occurrence of postoperative adverse events. The final models were selected using a backward stepwise process that sequentially eliminated variables with the weakest associations until all variables had P < .05.

Because the ACS-NSQIP reports timing data in calendar days, when the postoperative length of stay was equivalent to the postoperative day of diagnosis, it was not possible to ascertain whether the diagnosis occurred prior to or following discharge. For this study, when the postoperative length of stay was equivalent to the postoperative day of diagnosis, the adverse event was considered to have been diagnosed following discharge. The rationale for this is that for most of the adverse events, it was thought to be unlikely that an inpatient would be discharged before the end of the same day as an inpatient diagnosis. However, there was one exception to this rule; when the postoperative day of discharge, the postoperative length of stay, and the postoperative day of death were all equivalent, the adverse event was considered to have occurred prior to discharge. This is because when a patient dies during the initial inpatient stay, the ACS-NSQIP considers the postoperative length of stay to be equivalent to the postoperative day of death. This makes it much more likely that a diagnosis on the final hospital day had occurred in a patient who had not been discharged.

The mandatory ACS-NSQIP statement is “The American College of Surgeons National Surgical Quality Improvement Program and the hospitals participating in the ACS-NSQIP are the source of the data used herein; they have not verified and are not responsible for the statistical validity of the data analysis or the conclusions derived by the authors.”²⁶

Continue to: RESULTS...

RESULTS

In total, 19,873 geriatric patients undergoing a hip fracture surgery were identified (Table 1). The rates of adverse events ranged from 6.7% for urinary tract infection to 0.6% for pulmonary embolism (Table 2).

Table 1. Patient Population

Abbreviation: COPD, chronic obstructive pulmonary disease.

Table 2. Patients with Adverse Events Diagnosed During the First 30 postoperative days (N = 19,873)

Abbreviation: CI, confidence interval.

Figure 1 depicts the timing of postoperative adverse events in detail in histograms and timing curves. For the earliest diagnosed adverse events, the rate of adverse events had diminished by postoperative day 30. For the later diagnosed adverse events, the rate of adverse events remained high at postoperative day 30.

Figure 2 provides the summary statistics for adverse events diagnosed in the first 30 postoperative days. The median postoperative day of diagnosis (and the interquartile range) was 3 (1-5) for myocardial infarction, 3 (0-8) for cardiac arrest requiring cardiopulmonary resuscitation, 3 (1-10) for stroke, 4 (2-10) for pneumonia, 4 (2-11) for pulmonary embolism, 7 (2-13) for urinary tract infection, 9 (4-16) for deep vein thrombosis, 9 (4-18) for sepsis, 11 (6-19) for mortality, and 16 (11-22) for surgical site infection.

Figure 3 depicts the timing of adverse events relative to discharge. The proportions of adverse events diagnosed prior to discharge were 81.0% for myocardial infarction, 77.8% for stroke, 76.1% for cardiac arrest requiring cardiopulmonary resuscitation, 71.9% for pulmonary embolism, 71.1% for pneumonia, 58.0% for urinary tract infection, 52.1% for sepsis, 46.9% for deep vein thrombosis, 44.3% for mortality, and 27.6% for surgical site infection.

Table 3 shows the independent risk factors for earlier occurrence of adverse events. Following multivariate stepwise selection of final models, at least 1 patient characteristic was independently associated with the timing of cardiac arrest, stroke, urinary tract infection, deep vein thrombosis, and death. In contrast, no patient characteristics were independently associated with the timing of myocardial infarction, pneumonia, pulmonary embolism, sepsis, and surgical site infection.

Table 3. Timing of Diagnosis of Adverse Events^a

^aBaseline characteristics that were independently associated with the timing of each adverse event were identified through a backwards stepwise selection process initially including all characteristics listed in Table 1, and sequentially excluding characteristics with the weakest associations until only characteristics with P < .05 remained. Independent associations with the timing of cardiac arrest, stroke, urinary tract infection, deep vein thrombosis, and death are shown. There were no characteristics independently associated with timing of myocardial infarction, pneumonia, pulmonary embolism, sepsis, or surgical site infection; hence, these adverse events are not listed in the table.

^bFrom final Cox proportional hazards models identified through multivariate stepwise selection.

Continue to: DISCUSSION...

DISCUSSION

Adverse events are extremely common following a geriatric hip fracture surgery.^1-4 Despite extensive investigation regarding methods to prevent these events,^5-12 there is limited published description of the timing at which such events occur. This study used a large prospectively followed up cohort of geriatric patients undergoing a hip fracture surgery to deliver a better description of the timing of adverse events than was previously available. The findings of this study should enable more targeted clinical surveillance, inform patient counseling, and help determine the duration of follow-up required for studies on adverse events.

There was wide variability in the timing at which the different postoperative adverse events were diagnosed (Figures 1, 2). Myocardial infarction was diagnosed the earliest, with more than three-fourth of diagnoses in the first postoperative week. Other relatively early-diagnosed adverse events included cardiac arrest requiring cardiopulmonary resuscitation, stroke, pneumonia, and pulmonary embolism.

The latest-diagnosed adverse event was surgical site infection (Figures 1, 2). Surgical site infection was actually the only adverse event with a rate of diagnosis during the first week that was lower than the rate of diagnosis later in the month (as can be seen by the inflection in the timing curve for surgical site infection in Figure 1). Mortality showed a relatively consistent rate of diagnosis throughout the entire first postoperative month. Other relatively late-diagnosed postoperative events, including sepsis, deep vein thrombosis, and urinary tract infection, showed varying degrees of decreased rate of diagnosis near the end of the first postoperative month. Of note, for the later-diagnosed adverse events, the estimated median and interquartile ranges (Figure 2) were presumably quite biased toward earlier diagnosis, as the 30-day follow-up period clearly failed to capture a large proportion of later-occurring adverse events (Figure 1).

Certain risk factors were independently associated with earlier occurrence of adverse events. Perhaps most strikingly, body mass index in the obese range was associated with substantially earlier occurrence of deep vein thrombosis (median of 5 vs 10 days). This finding suggests that clinical monitoring for deep vein thrombosis should be performed earlier in patients with greater body mass index. Also notable is the earlier occurrence of cardiac arrest and death among patients with end-stage renal disease than among those without. Patients with end-stage renal disease may have a greater risk for these adverse events immediately following the cardiac stresses of surgery.²⁷ Similarly, such patients may be more prone to early electrolyte abnormalities and arrhythmia.

Continue to: In addition to its clinical implications, this study...

In addition to its clinical implications, this study informs about the interpretation of the many studies of adverse events following hip fracture procedures that have been conducted using retrospective data. Several such studies have relied on inpatient-only administrative databases.^{4,13,14,28-35} As clearly demonstrated in Figure 3, for most of the commonly studied adverse events, inpatient-only databases failed to capture a large proportion of adverse events occurring in the first postoperative month. This highlights a substantial limitation of this commonly published type of study that is often not emphasized in the literature.

There has also been an increase in the publication of studies of adverse events following a hip fracture surgery using the ACS-NSQIP data.^{3,13,14,17,18,21} As discussed, the ACS-NSQIP provides data on 30-days of follow-up. This relatively extended follow-up is often touted as a distinct advantage. However, this study demonstrates that even the 30-day follow-up afforded by the ACS-NSQIP is limited in its ability to enable investigation of the later-occurring adverse events (Figure 1). In particular, the rate of surgical site infection shows little sign of slowing by postoperative day 30. Similarly, the rates of mortality, sepsis, deep vein thrombosis, and urinary tract infection remain substantial.

This study does have limitations. First, as discussed, the duration of follow-up is a limitation of any ACS-NSQIP-based investigation, including this study. Second, the ACS-NSQIP does not capture relevant orthopedic-specific outcomes (eg, screw cutout). In addition, it could not be determined with certainty whether adverse events occurring on the final hospital day occurred prior to or following discharge. However, only a small proportion of most of the adverse events was diagnosed on the final hospital day. Finally, the ACS-NSQIP reports on days from the operation until diagnosis of the adverse event. Although some adverse events are probably diagnosed quickly after they have occurred (eg, myocardial infarction and cardiac arrest), other adverse events may have a delayed diagnosis (eg, surgical site infection may be identified days after its initial occurrence during a follow-up examination). Therefore, it is important to note the subtle distinction between occurrence and diagnosis throughout the article. This article reports on the timing of diagnosis, not actual occurrence.

CONCLUSION

The timing of postoperative adverse events has been understudied in the past. This may be due to an inability of standard single- or multi-institutional investigations to achieve sample sizes adequate to study the less commonly occurring adverse events. Using a relatively new prospective surgical registry, this study provides a far more detailed description of the timing of adverse events following surgery than was previously available. The authors anticipate that these data can be used to inform patient counseling, target clinical surveillance, and direct clinical research. The authors chose to study the timing of postoperative adverse events following geriatric hip fracture surgery because of the high rate of adverse events associated with the procedure. However, future ACS-NSQIP studies may involve characterization of the timing of adverse events following other orthopedic and non-orthopedic procedures.

This paper will be judged for the Resident Writer’s Award.

Despite these extensive research efforts, there is currently little information in the literature regarding when postoperative adverse events occur. A clear depiction of the timing of adverse events could help target clinical surveillance, inform patient counseling, and determine the duration of follow-up required for studies. The reason that the timing of adverse events has not been previously characterized may be that the sample sizes available through standard single- or multi-institutional studies may be insufficient to accurately characterize the timing of rare adverse events (eg, myocardial infarction, stroke, etc.). Moreover, although administrative datasets have become common data sources for investigation of rare postoperative adverse events,^13-16 such data sources often do not contain data on the timing of diagnosis.

The American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) is a relatively new and growing surgical registry.^1,3,13-22 The registry follows up patients undergoing surgical procedures at several hundred community and academic institutions nationwide. Unlike the administrative datasets discussed above, the ACS-NSQIP characterizes the postoperative day of diagnosis of well-defined adverse events during the first 30 postoperative days.²²

In this study, data collected by the ACS-NSQIP are used to characterize the timing of 10 specific postoperative adverse events following a geriatric hip fracture surgery.

Continue to: METHODS...

METHODS

A retrospective analysis of data collected prospectively through the ACS-NSQIP was conducted. Geriatric patients who underwent hip fracture surgery during 2010 to 2013 were identified. Specific inclusion criteria were (1) International Classification of Diseases, Ninth Revision, diagnosis code 820, (2) primary Current Procedural Terminology codes 27125, 27130, 27235, 27236, 27244, or 27245, and (3) age ≥70 years.

The ACS-NSQIP captures patient demographic, comorbidity, and procedural characteristics at baseline.²² At the end of the 30-day follow-up period, the ACS-NSQIP personnel review both inpatient and outpatient charts to characterize the occurrence vs nonoccurrence of specific postoperative adverse events.^22-25 When an adverse event does occur, the postoperative day of diagnosis is recorded.

For this study, the following adverse event categories were investigated: myocardial infarction, cardiac arrest requiring cardiopulmonary resuscitation, stroke, pneumonia, pulmonary embolism, urinary tract infection, deep vein thrombosis, sepsis (either with or without shock), mortality, and surgical site infection (including superficial surgical site infection, deep surgical site infection, and organ or space surgical site infection). Detailed definitions of each adverse event are provided in ACS-NSQIP materials.²²

First, the 30-day incidence (and the associated 95% confidence interval) was determined for each adverse event. Second, the median postoperative day of diagnosis (and the associated interquartile range) was determined for each adverse event. Third, the postoperative length of stay was used to estimate the proportion of diagnoses occurring prior to vs following discharge for each adverse event. Finally, multivariate Cox proportional hazards models were used to identify independent risk factors for earlier occurrence of postoperative adverse events. The final models were selected using a backward stepwise process that sequentially eliminated variables with the weakest associations until all variables had P < .05.

Because the ACS-NSQIP reports timing data in calendar days, when the postoperative length of stay was equivalent to the postoperative day of diagnosis, it was not possible to ascertain whether the diagnosis occurred prior to or following discharge. For this study, when the postoperative length of stay was equivalent to the postoperative day of diagnosis, the adverse event was considered to have been diagnosed following discharge. The rationale for this is that for most of the adverse events, it was thought to be unlikely that an inpatient would be discharged before the end of the same day as an inpatient diagnosis. However, there was one exception to this rule; when the postoperative day of discharge, the postoperative length of stay, and the postoperative day of death were all equivalent, the adverse event was considered to have occurred prior to discharge. This is because when a patient dies during the initial inpatient stay, the ACS-NSQIP considers the postoperative length of stay to be equivalent to the postoperative day of death. This makes it much more likely that a diagnosis on the final hospital day had occurred in a patient who had not been discharged.

The mandatory ACS-NSQIP statement is “The American College of Surgeons National Surgical Quality Improvement Program and the hospitals participating in the ACS-NSQIP are the source of the data used herein; they have not verified and are not responsible for the statistical validity of the data analysis or the conclusions derived by the authors.”²⁶

Continue to: RESULTS...

RESULTS

In total, 19,873 geriatric patients undergoing a hip fracture surgery were identified (Table 1). The rates of adverse events ranged from 6.7% for urinary tract infection to 0.6% for pulmonary embolism (Table 2).

Table 1. Patient Population

Abbreviation: COPD, chronic obstructive pulmonary disease.

Table 2. Patients with Adverse Events Diagnosed During the First 30 postoperative days (N = 19,873)

Abbreviation: CI, confidence interval.

Figure 1 depicts the timing of postoperative adverse events in detail in histograms and timing curves. For the earliest diagnosed adverse events, the rate of adverse events had diminished by postoperative day 30. For the later diagnosed adverse events, the rate of adverse events remained high at postoperative day 30.

Figure 2 provides the summary statistics for adverse events diagnosed in the first 30 postoperative days. The median postoperative day of diagnosis (and the interquartile range) was 3 (1-5) for myocardial infarction, 3 (0-8) for cardiac arrest requiring cardiopulmonary resuscitation, 3 (1-10) for stroke, 4 (2-10) for pneumonia, 4 (2-11) for pulmonary embolism, 7 (2-13) for urinary tract infection, 9 (4-16) for deep vein thrombosis, 9 (4-18) for sepsis, 11 (6-19) for mortality, and 16 (11-22) for surgical site infection.

Figure 3 depicts the timing of adverse events relative to discharge. The proportions of adverse events diagnosed prior to discharge were 81.0% for myocardial infarction, 77.8% for stroke, 76.1% for cardiac arrest requiring cardiopulmonary resuscitation, 71.9% for pulmonary embolism, 71.1% for pneumonia, 58.0% for urinary tract infection, 52.1% for sepsis, 46.9% for deep vein thrombosis, 44.3% for mortality, and 27.6% for surgical site infection.

Table 3 shows the independent risk factors for earlier occurrence of adverse events. Following multivariate stepwise selection of final models, at least 1 patient characteristic was independently associated with the timing of cardiac arrest, stroke, urinary tract infection, deep vein thrombosis, and death. In contrast, no patient characteristics were independently associated with the timing of myocardial infarction, pneumonia, pulmonary embolism, sepsis, and surgical site infection.

Table 3. Timing of Diagnosis of Adverse Events^a

^aBaseline characteristics that were independently associated with the timing of each adverse event were identified through a backwards stepwise selection process initially including all characteristics listed in Table 1, and sequentially excluding characteristics with the weakest associations until only characteristics with P < .05 remained. Independent associations with the timing of cardiac arrest, stroke, urinary tract infection, deep vein thrombosis, and death are shown. There were no characteristics independently associated with timing of myocardial infarction, pneumonia, pulmonary embolism, sepsis, or surgical site infection; hence, these adverse events are not listed in the table.

^bFrom final Cox proportional hazards models identified through multivariate stepwise selection.

Continue to: DISCUSSION...

DISCUSSION

Adverse events are extremely common following a geriatric hip fracture surgery.^1-4 Despite extensive investigation regarding methods to prevent these events,^5-12 there is limited published description of the timing at which such events occur. This study used a large prospectively followed up cohort of geriatric patients undergoing a hip fracture surgery to deliver a better description of the timing of adverse events than was previously available. The findings of this study should enable more targeted clinical surveillance, inform patient counseling, and help determine the duration of follow-up required for studies on adverse events.

There was wide variability in the timing at which the different postoperative adverse events were diagnosed (Figures 1, 2). Myocardial infarction was diagnosed the earliest, with more than three-fourth of diagnoses in the first postoperative week. Other relatively early-diagnosed adverse events included cardiac arrest requiring cardiopulmonary resuscitation, stroke, pneumonia, and pulmonary embolism.

The latest-diagnosed adverse event was surgical site infection (Figures 1, 2). Surgical site infection was actually the only adverse event with a rate of diagnosis during the first week that was lower than the rate of diagnosis later in the month (as can be seen by the inflection in the timing curve for surgical site infection in Figure 1). Mortality showed a relatively consistent rate of diagnosis throughout the entire first postoperative month. Other relatively late-diagnosed postoperative events, including sepsis, deep vein thrombosis, and urinary tract infection, showed varying degrees of decreased rate of diagnosis near the end of the first postoperative month. Of note, for the later-diagnosed adverse events, the estimated median and interquartile ranges (Figure 2) were presumably quite biased toward earlier diagnosis, as the 30-day follow-up period clearly failed to capture a large proportion of later-occurring adverse events (Figure 1).

Certain risk factors were independently associated with earlier occurrence of adverse events. Perhaps most strikingly, body mass index in the obese range was associated with substantially earlier occurrence of deep vein thrombosis (median of 5 vs 10 days). This finding suggests that clinical monitoring for deep vein thrombosis should be performed earlier in patients with greater body mass index. Also notable is the earlier occurrence of cardiac arrest and death among patients with end-stage renal disease than among those without. Patients with end-stage renal disease may have a greater risk for these adverse events immediately following the cardiac stresses of surgery.²⁷ Similarly, such patients may be more prone to early electrolyte abnormalities and arrhythmia.

Continue to: In addition to its clinical implications, this study...

In addition to its clinical implications, this study informs about the interpretation of the many studies of adverse events following hip fracture procedures that have been conducted using retrospective data. Several such studies have relied on inpatient-only administrative databases.^{4,13,14,28-35} As clearly demonstrated in Figure 3, for most of the commonly studied adverse events, inpatient-only databases failed to capture a large proportion of adverse events occurring in the first postoperative month. This highlights a substantial limitation of this commonly published type of study that is often not emphasized in the literature.

There has also been an increase in the publication of studies of adverse events following a hip fracture surgery using the ACS-NSQIP data.^{3,13,14,17,18,21} As discussed, the ACS-NSQIP provides data on 30-days of follow-up. This relatively extended follow-up is often touted as a distinct advantage. However, this study demonstrates that even the 30-day follow-up afforded by the ACS-NSQIP is limited in its ability to enable investigation of the later-occurring adverse events (Figure 1). In particular, the rate of surgical site infection shows little sign of slowing by postoperative day 30. Similarly, the rates of mortality, sepsis, deep vein thrombosis, and urinary tract infection remain substantial.

This study does have limitations. First, as discussed, the duration of follow-up is a limitation of any ACS-NSQIP-based investigation, including this study. Second, the ACS-NSQIP does not capture relevant orthopedic-specific outcomes (eg, screw cutout). In addition, it could not be determined with certainty whether adverse events occurring on the final hospital day occurred prior to or following discharge. However, only a small proportion of most of the adverse events was diagnosed on the final hospital day. Finally, the ACS-NSQIP reports on days from the operation until diagnosis of the adverse event. Although some adverse events are probably diagnosed quickly after they have occurred (eg, myocardial infarction and cardiac arrest), other adverse events may have a delayed diagnosis (eg, surgical site infection may be identified days after its initial occurrence during a follow-up examination). Therefore, it is important to note the subtle distinction between occurrence and diagnosis throughout the article. This article reports on the timing of diagnosis, not actual occurrence.

CONCLUSION

The timing of postoperative adverse events has been understudied in the past. This may be due to an inability of standard single- or multi-institutional investigations to achieve sample sizes adequate to study the less commonly occurring adverse events. Using a relatively new prospective surgical registry, this study provides a far more detailed description of the timing of adverse events following surgery than was previously available. The authors anticipate that these data can be used to inform patient counseling, target clinical surveillance, and direct clinical research. The authors chose to study the timing of postoperative adverse events following geriatric hip fracture surgery because of the high rate of adverse events associated with the procedure. However, future ACS-NSQIP studies may involve characterization of the timing of adverse events following other orthopedic and non-orthopedic procedures.

This paper will be judged for the Resident Writer’s Award.

This study sought to describe the trends in incidence as well as the factors influencing mortality and the risk of complications for patients admitted to US hospitals with an acetabular fracture using the National Hospital Discharge Survey (NHDS), the most recently available Centers for Disease Control and Prevention data, which is also one of the largest inpatient databases in the US. Knowledge of the factors influencing outcomes for patients admitted with acetabular fractures may improve management and decrease complications.

METHODS

NATIONAL HOSPITAL DISCHARGE SURVEY

The NHDS, developed by the National Center for Healthcare Statistics division of the Centers for Disease Control and Prevention,¹⁸ was used to estimate the incidence of acetabular fractures and to evaluate the risk factors for ensuing mortality and inpatient complications. The NHDS is a publically available survey providing demographic and medical data for inpatients discharged from non-federal, short-stay hospitals in the US.¹⁹ The NHDS is the principal database used by the US government for monitoring hospital use and is considered the most comprehensive of all inpatient surgical databases in use today.¹⁹ The survey uses International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM) codes²⁰ to classify medical diagnoses and procedures. The NHDS uses a stratified, multistage probability design to collect demographic information (age, gender, race), expected source of payment (insurance status), medical information of up to 7 discharge diagnoses and up to 4 procedures, length of care, hospital size, US region, and inpatient outcomes including discharge destination.²¹ To ensure unbiased national sampling of inpatient records, the NHDS uses a complex, 3-stage probability design including inflation by reciprocals of the probabilities of sample selection, adjustment for no response, and population weighting ratio adjustments.¹⁹ This study did not require approval by the Institutional Review Board because the NHDS is a publically available database with no patient-identifying information.

Continue to: PATIENT SELECTION...

PATIENT SELECTION

All patients admitted to hospitals in the US with a fracture of the acetabulum between 1990 and 2010 were identified using ICD-9-CM codes. Discharges with a diagnosis code (ICD-9-CM) of closed fracture of the acetabulum (808.0) or open fracture of the acetabulum (808.1) were identified using previously described techniques.²² The database was subsequently queried to identify patients treated using open reduction and internal fixation (ORIF) (ICD-9-CM, 79.30/79.39), closed reduction and internal fixation (CRIF) (ICD-9-CM, 79.10/79.19), or external (ICD-9-CM, 78.10/78.19) or internal (ICD-9-CM, 78.50/78.59) fixation without reduction. Demographic variables were then collected, including age, sex, primary diagnosis, associated diagnoses, type of fracture (open vs closed), prevalence of comorbidities, length of stay, and discharge destination. The complication screening package²³ was used to determine the incidence of complications. The variable adverse event was created on the basis of the variables postoperative bleeding (998.1), acute postoperative infection (998.5), acute postoperative anemia (285.1), acute renal failure (584), acute myocardial infarction (410), pulmonary embolism (415.1), induced mental disorder (293), pneumonia (480-486), pulmonary insufficiency (518.5), deep venous thrombosis (453.4), intubation (96.xx), and blood transfusion (99.x).

STATISTICAL ANALYSIS

Because of the large sample size, a normal distribution of the data was assumed. Differences between categorical variables were compared using the Pearson chi square test, while the independent-samples t test was used to compare differences between continuous variables. To determine independent predictors of in-hospital outcomes (death, adverse events, requirement for blood transfusion, or treatment with ORIF), all variables present in at least 2% of the population²⁴ were included in a multivariable binary logistic regression model. For in-hospital adverse events, a 1% cutoff was used due to their lower rates of occurrence, as previously described.²⁵The dichotomous variables were death, presence of adverse events, receipt of blood transfusion, and treatment with ORIF. A multivariable regression model allows for the control of potential confounders, isolating the effect of individual variables on inpatient outcomes. Covariates accounted for in the regression model included gender, age, region of the country, and preexisting comorbidities (diabetes mellitus, hypertension, congestive heart failure, coronary artery disease, atrial fibrillation). To assess the association between individual variables and inpatient outcomes, odds ratios and confidence intervals were calculated. A P value of <.001 was used to define statistical significance, correcting for multiple comparisons, as previously described.²⁵ US census data were used to obtain national population estimates for each year of the study from 1990 to 2010.²⁶ Rates were presented as the number of acetabular fractures per 100,000 standard population. All data were analyzed using the software Statistical Package for the Social Sciences [SPSS] version 20.

RESULTS

INCIDENCE AND DEMOGRAPHICS

A cohort representative of 497,389 patients with a diagnosis of acetabular fracture was identified between 1990 and 2010 (Table 1). In 1990, 19,560 cases (7.84 per 100,000 capita) of acetabular fractures were recoded, while in 2010, the number of cases increased to 29,373 or 9.5 per 100,000 capita (P < .001) (Table 2). The mean age of patients with an acetabular fracture was 52.6 years (standard deviation [SD], 23.7) and 60.6% were male (Table 1). The most frequently associated diagnosis was closed fracture of the pelvis (29.8%) followed by fracture of the femur (13.1%) and closed fracture of the ilium (3.8%) (Table 1). Of the total cohort, 23.2% underwent ORIF (Table 1). In 1990, 12.6% of patients with a diagnosis of acetabular fracture underwent ORIF, whereas 20.4% of patients underwent ORIF in 2010 (P < .001) (Table 2). Average length of hospital stay was 8.3 days (SD, 17.9) overall (Table 1). In 1990 the average length of stay was 17.0 days (SD, 14.9), decreasing to 10.3 days (SD, 9.3) in 2010 (P < .001) (Table 2).

Table 1. Patient Characteristics for Patients with Acetabular Fractures in the United States from 1990 to 2007

Abbreviation: SD, standard deviation.

Table 2. Patient Characteristics in 1990, 1995, 1999, 2003, and 2007 Among Patients with Acetabular Fractures

Abbreviations: DOC, days of care; ORIF, open reduction internal fixation.

Continue to: MORTALITY...

MORTALITY

In-hospital mortality decreased from 5.9% in 1990 to 0.4% in 2010 (P < .001) (3.5% for the total cohort) (Tables 1 and 2). Multivariable logistic regression analysis demonstrated pulmonary insufficiency (odds ratio [OR], 9.07; 95% confidence interval [CI], 8.52-9.66; P < .01), pneumonia (OR, 3.22; 95% CI, 3.05-3.39; P < .01), and age >85 years (OR, 2.28; 95% CI, 2.16-2.40; P < .01) to be associated with the highest odds of inpatient mortality. CRIF (OR, 1.99; 95% CI, 1.78-2.23; P < .01), external fixator (OR, 1.82; 95% CI, 1.45-2.29; P < .01), and having received a blood transfusion (OR, 1.81; 95% CI, 1.71-1.91; P < .01) were also associated with increased odds of mortality. Treatment with ORIF (OR, 0.19; 95% CI, 0.17-0.20; P < .01) was independently associated with decreased odds of inpatient mortality, as was age <20 years (OR, 0.26; 95% CI, 0.23-0.30; P < .01) (model fit: for omnibus test of model coefficients, X = 25,966 P < .01; Nagelkerke, R² = 0.20) (Table 3).

Table 3. Logistic Regression for Predictors of Mortality Among Patients with Acetabular Fractures (n = 403,927)

Abbreviations: CI, confidence interval; DOC, days of care; OR, odds ratio.

COMORBIDITIES AND ADVERSE EVENTS

The prevalence of comorbidities and adverse events is listed in Tables 4 and 5, respectively. Hypertensive disease was the most common comorbidity at 15.3%, followed by diabetes mellitus at 6.9%. Overall, 25.9% of patients experienced an in-hospital adverse event, with the most common being postoperative anemia (7.3%) and blood transfusion (8.1%) (Tables 1 and 5). The percentage of patients experiencing an adverse event increased from 10.9% in 1990 to 37.6% in 2010 (P < .01) (Table 2). Multivariable logistic regression analysis revealed CRIF (OR, 3.08; 95% CI, 2.91-3.26; P < .01), coronary artery disease (OR, 2.02; 95% CI, 1.91-2.15; P < .01), associated femoral neck fracture (OR, 1.53; 95% CI, 1.47-1.60; P < .01), and ORIF (OR, 1.22; 95% CI, 1.20-1.24; P < .01) to be associated with higher odds of inpatient adverse events (model fit: for omnibus test of model coefficients, X = 160,275, P < .01; Nagelkerke, R² = 0.41) (Table 6).

Table 4. Prevalence of Comorbidities in Patients with Acetabular Fractures Between 1990 and 2007 (n = 403.927)

Abbreviation: ICD-9, International Classifications of Diseases, 9th Revision.

Table 5. Prevalence of In-Hospital Adverse Events Among Patients with Acetabular Fractures Between 1990 and 2007 (n = 403,927)

Abbreviation: ICD-9, International Classifications of Diseases, 9th Revision.

Table 6. Logistic Regression for Predictors of Adverse Events Among Patients Hospitalized for Acetabular Fracture (n = 403,927)

Abbreviations: CI, confidence interval; DOC, days of care; OR, odds ratio.

BLOOD TRANSFUSION

Overall, 7.3% of patients experienced acute postoperative anemia (Table 5). Between 1990 and 2010, the percentage of patients receiving blood transfusions increased from 0.3% to 9.5%, respectively (P < .01) (Table 2). In multivariable logistic regression analysis, patients treated with ORIF (OR, 8.13; 95% CI, 7.91-8.36; P < .01), those with congestive heart failure (OR, 4.23; 95% CI, 4.06-4.41; P < .01), those with an associated femur fracture (OR, 3.13; 95% CI, 2.99-3.27; P < .01), those with atrial fibrillation (OR, 1.96; 95% CI, 1.88-2.05; P < .01), and those treated with CRIF (OR, 1.42; 95% CI, 1.29-1.56; P < .01) were associated with significantly higher odds of blood transfusion (model fit: omnibus test of model coefficients, X = 42,653, P < .01; Nagelkerke, R² = 0.19) (Table 7).

Table 7. Logistic Regression for Predictors of the Requirement for Blood Transfusion Among Patients with Acetabular Fractures (n = 403,927)

Abbreviations: CI, confidence interval; DOC, days of care; OR, odds ratio.

TREATMENT WITH ORIF

Over the 20-year study period, 23.2% of patients with acetabular fractures were treated with ORIF (Table 1). In 1990, 12.6% of patients underwent ORIF, while in 2010 this percentage increased to 20.4% (P < .001) (Table 2). Multivariable logistic regression analysis demonstrated that age between 41 and 60 years (OR, 1.88; 95% CI, 1.78-1.98; P < .01) was associated with the highest odds of undergoing ORIF. Age 20 to 40 years (OR, 1.86; 95% CI, 1.76-1.97; P < .01), age <20 years (OR, 1.82; 95% CI, 1.72-1.93; P < .01), and male gender (OR, 1.65; 95% CI, 1.63-1.68; P < .01) were also associated with being treated by ORIF. In contrast, coronary artery disease (OR, 0.27; 95% CI, 0.25-0.30; P < .01), age >85 years (OR, 0.46; 95% CI, 0.44-0.47; P < .01), and congestive heart failure (OR, 0.48; 95% CI, 0.46-0.51; P < .01) were associated with the lowest odds of undergoing ORIF (model fit: omnibus test of model coefficients, X = 71,118, P < .01; Nagelkerke, R² = 0.20) (Table 8).

Table 8. Logistic Regression for Predictors of the Requirement for Discharge to Another Inpatient Facility Among Patients with Acetabular Fractures (n = 403,927)

Abbreviations: CI, confidence interval; DOC, days of care; OR, odds ratio.

Continue to: DISCUSSION...

DISCUSSION

This study evaluates the incidence of acetabular fractures in the US between 1990 and 2010, and identifies prognostic factors associated with complications and death. The study demonstrates an increase in the population-adjusted incidence of acetabular fractures between 1990 and 2010 (7.84 cases per 100,000 capita to 9.5 cases per 100,000 capita), in contrast to the decreasing trend reported by Mauffrey and colleagues.¹¹ Some studies suggest that up to 80% of acetabular fractures are associated with motor vehicle collisions and motorcycle accidents.^9,27 While the rate of motor vehicle accidents has remained stable over the study period, motorcycle ownership and deaths more than doubled between 2001 and 2008,²⁸ primarily among individuals over 40 years of age. In this study, the mean age of patients with acetabular fractures ranged from 48 to 57 years. The dramatic increase in motorcycle ownership and deaths in these age groups may partially explain the rising incidence of acetabular fractures. The other possibility is that changes in automobile design and safety equipment may have altered the injury patterns observed in patients surviving motor vehicle crashes. Compared to the United Kingdom, in which studies report a fixed incidence of 3 per 100,000 capita¹ between 1988 and 2003, the incidence of acetabular fractures in the US is greater. In contrast, the incidence of acetabular fractures reported in this study is less than the 20 per 100,000 reported in Sweden between 1976 and 1985,²⁹ or the 37 per 100,000 reported in Rochester, Minnesota between 1968 and 1977,³⁰ which may be due to increased seatbelt usage.³¹

In addition to the national incidence, this study demonstrated that the proportion of patients with acetabular fractures treated with ORIF increased from 12.6% to 20.4% between 1990 and 2010. This is substantially lower than the 77% reported by Ochs and colleagues³² in a German population. Concurrent with the increase in ORIF, there was a decrease in in-hospital mortality from 5.9% in 1990 to 0.4% in 2010. The initial mortality rates in this study are comparable to much earlier reports and some small studies,^9,32-37 but the rates reported in the later years of this study show a substantial decrease that is likely a more accurate estimation of the current incidence. The improved survival rates may be due to advances in the operative treatment of acetabular fractures, in which mechanical stabilization allows for early patient mobilization and facilitation of optimal nursing care.³⁸ With ORIF becoming the standard of care for displaced acetabular fractures,⁹ numerous reports have demonstrated an association between early definitive fixation and improved survival.^17,39,40 This is similar to our study, which found ORIF to be associated with the lowest odds of mortality in multivariate logistic regression analysis. It is possible that advances in patient care by intensivists over this period have also contributed to the decrease in mortality, but the correlation with operative treatment in this study is very strong and agrees well with prior studies.¹⁶ Moreover, multiple studies have demonstrated decreased in-hospital mortality among patients undergoing various orthopedic surgical procedures during this period.^41-43 The correlation with operative treatment in this study agrees well with prior studies.¹⁶

In contrast, higher odds of mortality were seen in patients over the age of 85 years with pulmonary insufficiency, congestive heart failure, pneumonia, or an associated femur or pelvic fracture. This is similar to prior reports in which patients with combined acetabulum and pelvic ring injuries fared worse than those with isolated injures,^44,45 as did patients with associated non-musculoskeletal injuries.⁴⁶ The finding that age over 85 years was associated with higher odds of mortality likely reflects the increased number of comorbidities and decreased physiologic reserve seen in this patient population. Finally, male gender was associated with higher odds of in-hospital mortality. There are 2 possible explanations for this: Either there is gender dimorphism in sex hormones and cytokine activity in response to hemorrhage and sepsis,^38,47 or there is a greater tendency for males to be involved in higher energy accidents with more severe concomitant injuries.

The results of multivariable regression analysis demonstrated that patients were more likely to require blood transfusion if they were managed surgically or had atrial fibrillation, congestive heart failure, or associated femur fracture. Not surprisingly, concurrent pelvic fracture was also associated with higher odds of blood transfusion, as pelvic hemorrhage is reported to be the cause of death in up to half of patients who die following a pelvic fracture.⁴⁶

Between 1990 and 2010, in-hospital days of care decreased from 17.0 days to 10.3 days. While a decreased length of stay has been demonstrated in other orthopedic conditions over the study period,⁴¹ it is possible the decrease in length of stay demonstrated in this study is due to improved surgical technique and the implementation of early surgical intervention.^39,48-50 Plaisier and colleagues¹⁷ demonstrated superior functional outcomes, quicker return to baseline function, and decreased length of stay in patients treated with early ORIF of their acetabular fractures. Other studies have shown that the benefits of early surgery include improved reduction quality and ease of reduction,⁵¹ as well as control of bleeding, pain relief, and mobilization of the patient.³⁹ Another possible explanation for the decreased length of stay is the increased rate of discharge to other inpatient facilities, such as rehabilitation facilities, which was demonstrated in this study.

Continue to: Interestingly, male gender and younger age...

Interestingly, male gender and younger age were associated with operative management of the acetabular fracture. In contrast, there was a decreased likelihood of operative treatment among elderly patients and those patients with cardiac comorbidities. It is possible that the relationship we found between the likelihood of ORIF and age relates to the bimodal distribution of fractures, with higher energy and potentially more displaced fractures occurring in younger patients^3-5 and lower energy fractures in the elderly.

In contrast to decreasing in-hospital days of care, there was a rise in the number of adverse events between 1990 (10.9%) and 2010 (37.6%). This can be partially attributed to the increased rates of blood transfusion, which was received by 9.5% of patients with acetabular fractures in the final study year. Additionally, surgical intervention was associated with increased adverse events in this study, and surgical intervention increased over the study period. Other factors that may have contributed to an increase in adverse events include an aging population,⁵² as advanced age was independently associated with higher odds of adverse events in this study.

Despite the strengths of using large, national databases for epidemiological research,⁵³ this study has several limitations. Like all large databases, the NHDS is subject to error in coding and data entry.⁵⁴ Additionally, the database only allows for 7 diagnostic codes and 4 procedure codes per entry. As a result, the prevalence of comorbid conditions and adverse events may be underreported.²⁵ Moreover, the severity of a comorbid disease cannot be appreciated when dichotomously classified.⁵⁵ Another limitation is that the database only provides inpatient data, so complications that arise after discharge, as well as follow-up data, are unknown. Furthermore, the results of this study are limited to practice patterns in the US from 1990 to 2010. This database does not provide injury mechanisms, so we cannot distinguish between high-energy and low-energy injuries. Lastly, analysis of the different types of acetabular fractures was not performed since classification of acetabular fractures cannot be assessed with ICD-9 codes.

CONCLUSION

This study is the largest epidemiologic analysis of acetabular fractures in the US and also provides predictors of in-hospital mortality. The incidence of acetabular fractures in the US is increasing, while mortality is decreasing. Identifying risk factors associated with poor outcomes has the potential to change treatment strategies, resource allocation, in-hospital monitoring, and discharge planning for this patient population.

This paper will be judged for the Resident Writer’s Award.

This study sought to describe the trends in incidence as well as the factors influencing mortality and the risk of complications for patients admitted to US hospitals with an acetabular fracture using the National Hospital Discharge Survey (NHDS), the most recently available Centers for Disease Control and Prevention data, which is also one of the largest inpatient databases in the US. Knowledge of the factors influencing outcomes for patients admitted with acetabular fractures may improve management and decrease complications.

METHODS

NATIONAL HOSPITAL DISCHARGE SURVEY

The NHDS, developed by the National Center for Healthcare Statistics division of the Centers for Disease Control and Prevention,¹⁸ was used to estimate the incidence of acetabular fractures and to evaluate the risk factors for ensuing mortality and inpatient complications. The NHDS is a publically available survey providing demographic and medical data for inpatients discharged from non-federal, short-stay hospitals in the US.¹⁹ The NHDS is the principal database used by the US government for monitoring hospital use and is considered the most comprehensive of all inpatient surgical databases in use today.¹⁹ The survey uses International Classification of Diseases, 9th Revision, Clinical Modification (ICD-9-CM) codes²⁰ to classify medical diagnoses and procedures. The NHDS uses a stratified, multistage probability design to collect demographic information (age, gender, race), expected source of payment (insurance status), medical information of up to 7 discharge diagnoses and up to 4 procedures, length of care, hospital size, US region, and inpatient outcomes including discharge destination.²¹ To ensure unbiased national sampling of inpatient records, the NHDS uses a complex, 3-stage probability design including inflation by reciprocals of the probabilities of sample selection, adjustment for no response, and population weighting ratio adjustments.¹⁹ This study did not require approval by the Institutional Review Board because the NHDS is a publically available database with no patient-identifying information.

Continue to: PATIENT SELECTION...

PATIENT SELECTION

All patients admitted to hospitals in the US with a fracture of the acetabulum between 1990 and 2010 were identified using ICD-9-CM codes. Discharges with a diagnosis code (ICD-9-CM) of closed fracture of the acetabulum (808.0) or open fracture of the acetabulum (808.1) were identified using previously described techniques.²² The database was subsequently queried to identify patients treated using open reduction and internal fixation (ORIF) (ICD-9-CM, 79.30/79.39), closed reduction and internal fixation (CRIF) (ICD-9-CM, 79.10/79.19), or external (ICD-9-CM, 78.10/78.19) or internal (ICD-9-CM, 78.50/78.59) fixation without reduction. Demographic variables were then collected, including age, sex, primary diagnosis, associated diagnoses, type of fracture (open vs closed), prevalence of comorbidities, length of stay, and discharge destination. The complication screening package²³ was used to determine the incidence of complications. The variable adverse event was created on the basis of the variables postoperative bleeding (998.1), acute postoperative infection (998.5), acute postoperative anemia (285.1), acute renal failure (584), acute myocardial infarction (410), pulmonary embolism (415.1), induced mental disorder (293), pneumonia (480-486), pulmonary insufficiency (518.5), deep venous thrombosis (453.4), intubation (96.xx), and blood transfusion (99.x).

STATISTICAL ANALYSIS

Because of the large sample size, a normal distribution of the data was assumed. Differences between categorical variables were compared using the Pearson chi square test, while the independent-samples t test was used to compare differences between continuous variables. To determine independent predictors of in-hospital outcomes (death, adverse events, requirement for blood transfusion, or treatment with ORIF), all variables present in at least 2% of the population²⁴ were included in a multivariable binary logistic regression model. For in-hospital adverse events, a 1% cutoff was used due to their lower rates of occurrence, as previously described.²⁵The dichotomous variables were death, presence of adverse events, receipt of blood transfusion, and treatment with ORIF. A multivariable regression model allows for the control of potential confounders, isolating the effect of individual variables on inpatient outcomes. Covariates accounted for in the regression model included gender, age, region of the country, and preexisting comorbidities (diabetes mellitus, hypertension, congestive heart failure, coronary artery disease, atrial fibrillation). To assess the association between individual variables and inpatient outcomes, odds ratios and confidence intervals were calculated. A P value of <.001 was used to define statistical significance, correcting for multiple comparisons, as previously described.²⁵ US census data were used to obtain national population estimates for each year of the study from 1990 to 2010.²⁶ Rates were presented as the number of acetabular fractures per 100,000 standard population. All data were analyzed using the software Statistical Package for the Social Sciences [SPSS] version 20.

RESULTS

INCIDENCE AND DEMOGRAPHICS

A cohort representative of 497,389 patients with a diagnosis of acetabular fracture was identified between 1990 and 2010 (Table 1). In 1990, 19,560 cases (7.84 per 100,000 capita) of acetabular fractures were recoded, while in 2010, the number of cases increased to 29,373 or 9.5 per 100,000 capita (P < .001) (Table 2). The mean age of patients with an acetabular fracture was 52.6 years (standard deviation [SD], 23.7) and 60.6% were male (Table 1). The most frequently associated diagnosis was closed fracture of the pelvis (29.8%) followed by fracture of the femur (13.1%) and closed fracture of the ilium (3.8%) (Table 1). Of the total cohort, 23.2% underwent ORIF (Table 1). In 1990, 12.6% of patients with a diagnosis of acetabular fracture underwent ORIF, whereas 20.4% of patients underwent ORIF in 2010 (P < .001) (Table 2). Average length of hospital stay was 8.3 days (SD, 17.9) overall (Table 1). In 1990 the average length of stay was 17.0 days (SD, 14.9), decreasing to 10.3 days (SD, 9.3) in 2010 (P < .001) (Table 2).

Table 1. Patient Characteristics for Patients with Acetabular Fractures in the United States from 1990 to 2007

Abbreviation: SD, standard deviation.

Table 2. Patient Characteristics in 1990, 1995, 1999, 2003, and 2007 Among Patients with Acetabular Fractures

Abbreviations: DOC, days of care; ORIF, open reduction internal fixation.

Continue to: MORTALITY...

MORTALITY

In-hospital mortality decreased from 5.9% in 1990 to 0.4% in 2010 (P < .001) (3.5% for the total cohort) (Tables 1 and 2). Multivariable logistic regression analysis demonstrated pulmonary insufficiency (odds ratio [OR], 9.07; 95% confidence interval [CI], 8.52-9.66; P < .01), pneumonia (OR, 3.22; 95% CI, 3.05-3.39; P < .01), and age >85 years (OR, 2.28; 95% CI, 2.16-2.40; P < .01) to be associated with the highest odds of inpatient mortality. CRIF (OR, 1.99; 95% CI, 1.78-2.23; P < .01), external fixator (OR, 1.82; 95% CI, 1.45-2.29; P < .01), and having received a blood transfusion (OR, 1.81; 95% CI, 1.71-1.91; P < .01) were also associated with increased odds of mortality. Treatment with ORIF (OR, 0.19; 95% CI, 0.17-0.20; P < .01) was independently associated with decreased odds of inpatient mortality, as was age <20 years (OR, 0.26; 95% CI, 0.23-0.30; P < .01) (model fit: for omnibus test of model coefficients, X = 25,966 P < .01; Nagelkerke, R² = 0.20) (Table 3).

Table 3. Logistic Regression for Predictors of Mortality Among Patients with Acetabular Fractures (n = 403,927)

Abbreviations: CI, confidence interval; DOC, days of care; OR, odds ratio.

COMORBIDITIES AND ADVERSE EVENTS

The prevalence of comorbidities and adverse events is listed in Tables 4 and 5, respectively. Hypertensive disease was the most common comorbidity at 15.3%, followed by diabetes mellitus at 6.9%. Overall, 25.9% of patients experienced an in-hospital adverse event, with the most common being postoperative anemia (7.3%) and blood transfusion (8.1%) (Tables 1 and 5). The percentage of patients experiencing an adverse event increased from 10.9% in 1990 to 37.6% in 2010 (P < .01) (Table 2). Multivariable logistic regression analysis revealed CRIF (OR, 3.08; 95% CI, 2.91-3.26; P < .01), coronary artery disease (OR, 2.02; 95% CI, 1.91-2.15; P < .01), associated femoral neck fracture (OR, 1.53; 95% CI, 1.47-1.60; P < .01), and ORIF (OR, 1.22; 95% CI, 1.20-1.24; P < .01) to be associated with higher odds of inpatient adverse events (model fit: for omnibus test of model coefficients, X = 160,275, P < .01; Nagelkerke, R² = 0.41) (Table 6).

Table 4. Prevalence of Comorbidities in Patients with Acetabular Fractures Between 1990 and 2007 (n = 403.927)

Abbreviation: ICD-9, International Classifications of Diseases, 9th Revision.

Table 5. Prevalence of In-Hospital Adverse Events Among Patients with Acetabular Fractures Between 1990 and 2007 (n = 403,927)

Abbreviation: ICD-9, International Classifications of Diseases, 9th Revision.

Table 6. Logistic Regression for Predictors of Adverse Events Among Patients Hospitalized for Acetabular Fracture (n = 403,927)

Abbreviations: CI, confidence interval; DOC, days of care; OR, odds ratio.

BLOOD TRANSFUSION

Overall, 7.3% of patients experienced acute postoperative anemia (Table 5). Between 1990 and 2010, the percentage of patients receiving blood transfusions increased from 0.3% to 9.5%, respectively (P < .01) (Table 2). In multivariable logistic regression analysis, patients treated with ORIF (OR, 8.13; 95% CI, 7.91-8.36; P < .01), those with congestive heart failure (OR, 4.23; 95% CI, 4.06-4.41; P < .01), those with an associated femur fracture (OR, 3.13; 95% CI, 2.99-3.27; P < .01), those with atrial fibrillation (OR, 1.96; 95% CI, 1.88-2.05; P < .01), and those treated with CRIF (OR, 1.42; 95% CI, 1.29-1.56; P < .01) were associated with significantly higher odds of blood transfusion (model fit: omnibus test of model coefficients, X = 42,653, P < .01; Nagelkerke, R² = 0.19) (Table 7).

Table 7. Logistic Regression for Predictors of the Requirement for Blood Transfusion Among Patients with Acetabular Fractures (n = 403,927)

Abbreviations: CI, confidence interval; DOC, days of care; OR, odds ratio.

TREATMENT WITH ORIF

Over the 20-year study period, 23.2% of patients with acetabular fractures were treated with ORIF (Table 1). In 1990, 12.6% of patients underwent ORIF, while in 2010 this percentage increased to 20.4% (P < .001) (Table 2). Multivariable logistic regression analysis demonstrated that age between 41 and 60 years (OR, 1.88; 95% CI, 1.78-1.98; P < .01) was associated with the highest odds of undergoing ORIF. Age 20 to 40 years (OR, 1.86; 95% CI, 1.76-1.97; P < .01), age <20 years (OR, 1.82; 95% CI, 1.72-1.93; P < .01), and male gender (OR, 1.65; 95% CI, 1.63-1.68; P < .01) were also associated with being treated by ORIF. In contrast, coronary artery disease (OR, 0.27; 95% CI, 0.25-0.30; P < .01), age >85 years (OR, 0.46; 95% CI, 0.44-0.47; P < .01), and congestive heart failure (OR, 0.48; 95% CI, 0.46-0.51; P < .01) were associated with the lowest odds of undergoing ORIF (model fit: omnibus test of model coefficients, X = 71,118, P < .01; Nagelkerke, R² = 0.20) (Table 8).

Table 8. Logistic Regression for Predictors of the Requirement for Discharge to Another Inpatient Facility Among Patients with Acetabular Fractures (n = 403,927)