Erin S. Hart, NP

A 5-day-old infant was referred to the pediatric orthopedic clinic for evaluation of a left hip “clunk.” She is a firstborn child, born at full term (39 weeks) via cesarean delivery secondary to breech presentation. Her weight at birth was 7 lb 6 oz. The infant was noted to have a left hip clunk during a routine physical examination by her pediatrician, who made a referral to the pediatric orthopedic clinic for possible hip dysplasia. This is the patient’s first visit to the clinic.

There is no family history of hip dysplasia or other orthopedic abnormalities. The infant is a well-appearing, alert female measuring 20.5” in length and weighing 7 lb 4 oz. Vital signs are stable with no abnormality detected. The heart is regular in rate and rhythm, and the chest is clear bilaterally.

No cutaneous abnormalities are noted. The patient is able to move all her extremities spontaneously, and her spine is straight and normal with no evidence of spinal dysraphism. Her feet are normal bilaterally, with full range of motion and no equinovarus or metatarsus adductus deformity.

The neurologic examination is also unremarkable, with normal neonatal reflexes and excellent muscle tone throughout. 

Examination of the infant’s hips reveals a positive result on the Barlow test on the left side (the hip can be dislocated). There is also a positive Ortolani sign (the hip can be reduced), with asymmetric thigh skin folds noted (see Figures 1A and 1B, respectively).

Based on these positive physical examination findings, the patient was diagnosed with developmental dysplasia of the hip (DDH). Initial ultrasonography to confirm the diagnosis was not considered necessary, as the physical examination demonstrated obvious instability.1 The infant was placed in a Pavlik harness, which her parents were instructed should be worn full-time (see Figures 2A and 2B). She was scheduled for weekly follow-up visits for adjustments to the harness and serial hip examinations.

At the second follow-up visit, ultrasonography was performed, confirming the presence of dysplasia with decreased femoral head coverage and a steep socket (acetabulum). Use of the Pavlik harness was continued full-time for six weeks.

At age 6 weeks, the infant underwent a follow-up ultrasound to assess for improvement in the degree of dysplasia. The test revealed normal hips bilaterally with no evidence of DDH. Therefore, use of the Pavlik harness was discontinued. The parents were instructed to bring the child back in six months for a repeat clinical examination and an anteroposterior x-ray of the pelvis.¹

Discussion
The term developmental dysplasia of the hip (DDH) has replaced the more traditional term congenital hip dislocation because DDH more accurately reflects the variable characteristics that can be seen with this condition. As DDH may not be present at birth, the term congenital is misleading. We now know that DDH may occur in utero, perinatally, or during infancy and childhood.^2,3

Generally, DDH is used to describe an abnormal relationship between the femoral head and the acetabulum (see Figure 3⁴). The term represents a wide spectrum of abnormality, as shown in the Graf classification of hips in infants: type I refers to a normal hip; type II, immature development to mild dysplasia; type III, subluxation of the femoral head; and type 4, frank dislocation with severe instability.⁵

Diagnosing and managing DDH correctly requires the clinician to have a thorough understanding of the normal growth and development that occurs in the hip joint. Embryologically, the joint (including the femoral head and acetabulum) develops from the same primitive mesenchymal cells.⁶ By 11 to 12 weeks’ gestation, the initial structures of the hip joint are fully formed; theoretically, this is the earliest time at which a dislocation can occur.^2,7 DDH that develops at this stage would be called teratologic; this condition is seen most frequently in patients who have underlying neuromuscular conditions, such as myelodysplasia (spina bifida) or arthrogryposis. A typical dislocation takes place during the perinatal period in an infant who is otherwise healthy.²

Etiology
DDH occurs in about 11 of every 1,000 infants, with frank dislocations occurring in one to two infants per 10,000.⁸ The left hip is involved in approximately 60% of cases, the right in 20%, and both hips in about 20%. In the most common intrauterine fetal position, the left hip is lower than the right (usually abutting the mother’s sacrum) and is often in adduction. This is likely the reason that the left hip is more commonly affected by DDH.

DDH is believed to be multifactorial, with physiologic, genetic, and mechanical factors implicated in the etiology.³ The incidence of DDH varies with factors such as the patient’s age, race, and gender, the experience and training of the examiner, and the diagnostic criteria that are used.

Known risk factors for a positive newborn screening are shown in the table.^9,10 It is often helpful for clinicians to remember the “4F” mnemonic associated with DDH: female, firstborn, foot first, and family history.⁹

There is also an increased risk for DDH in patients with other conditions that are associated with intrauterine crowding. These include congenital muscular torticollis, metatarsus adductus, and congenital dislocation of the knee.²

Physical Examination
All newborn infants should be screened for DDH as part of the initial physical examination, with ultrasonography recommended for infants deemed at high risk for DDH and for those with inconclusive results on examination.^1,10,11 Providers should be aware that the newborn hip examination requires a considerable amount of practice and expertise.

A thorough medical history should always be obtained first, including gestational age, presentation (breech vs vertex), type of delivery (cesarean vs vaginal), gender, birth order, family history of DDH, ligamentous laxity, or myopathy.⁸

The examining clinician begins by placing the infant on a firm, flat surface. The infant should be as relaxed as possible. Next, the clinician observes both lower extremities for asymmetric thigh or buttock skin folds. Bilateral DDH can be very difficult to diagnose on the basis of this examination due to the lack of asymmetry (hips will have symmetric abnormality).

The Galeazzi sign is elicited by placing the infant supine with the hips and knees flexed to 90°.¹² With the hips in neutral abduction, the provider should determine whether the knees are at the same height. Unequal knee heights—a positive result for the Galeazzi sign—suggest femoral shortening (apparent leg length discrepancy), which may be explained by a hip dislocation. If both hips are dislocated, a false-negative result will often occur, since both will appear short and there will be no discrepancy.^2,12

Among physical examination techniques, the Ortolani and Barlow maneuvers are considered most reliable to detect hip instability in newborns and infants younger than 6 months^2,13,14 (review Figures 1A and 1B). The Ortolani test is used to detect the sensation of the dislocated hip reducing into the acetabulum, and the Barlow test elicits the unstable hip dislocating.² A palpable and occasionally audible clunk is considered a positive result on the Barlow test and usually indicates a diagnosis of DDH.¹⁴ High-pitched clicks or snaps frequently occur with hip range-of-motion maneuvers and during Ortolani and Barlow testing. These sounds are often attributed to snapping of the iliotibial band over the greater trochanter and do not usually signify dysplasia.¹⁵

Because DDH is a dynamic and evolving process, the physical findings on clinical examination change significantly, depending on the age of the infant or child. As an infant approaches age 3 months, limited hip abduction (especially when asymmetric) is often the most reliable physical examination finding in patients with DDH.¹² After age 3 to 4 months, Ortolani and Barlow testing will often produce negative results as progressive soft tissue contractures evolve.

Once a child begins to walk, gait abnormalities (eg, a short-limbed or waddling gait pattern) may raise suspicion for a diagnosis of DDH.⁷ It has been recommended that evaluation for DDH be performed at each routine office examination until the child is 12 months of age.¹

Treatment
The Pavlik harness is considered first-line treatment for DDH in infants younger than 6 months. The harness is a dynamic splint that allows the infant to engage in a sphere of active motion that encourages stabilization and deepening of the socket. The harness is applied with the knees flexed to about 90° and the hips in about 70° of abduction and 100° to 110° of flexion (as shown in Figures 2A and 2B).⁹

The duration of treatment depends on the infant’s age at presentation and the severity of DDH. Progress is judged by serial examinations and dynamic ultrasounds. The harness is worn full-time until clinical and radiographic examinations both yield normal results. After six weeks of treatment, the hips are examined out of the harness, and a repeat ultrasound is usually obtained. If findings are normal, use of the harness is ordinarily discontinued. Some patients will require harness use for a longer period in cases of delayed development of the acetabulum and/or severe laxity of the ligaments.⁹

The Pavlik harness is successful more than 90% of the time in newborns with DDH.⁸ Success rates have been reported as greatest in infants younger than 8 weeks at the time of treatment initiation, those with only one affected hip, and those with less severe disease (Graf types II or III).¹⁶

If ultrasonography shows no improvement after two to three weeks, it is usually recommended that the harness be discontinued; most orthopedic surgeons will then proceed with a closed or open reduction and spica body casting. Similarly, when the diagnosis of DDH is delayed until after ages 6 to 8 months, a closed reduction under anesthesia and placement of a spica body cast is usually the recommended treatment to maintain the hip in the reduced position.^17,18 Some older children (ages 1 to 5 years) may require bracing, traction, open reduction, and/or femoral or pelvic osteotomy.^17,18 It is believed that undiagnosed, untreated DDH can lead to early-onset degenerative hip disease (arthritis).¹

Patient/Family Education
The Pavlik harness is most effective when a consistent support system exists to educate parents about the importance of the harness, its care and maintenance, and the consequences of failure. Close monitoring of the infant’s progress is also essential to promoting adherence. Application and removal of the harness should be demonstrated to the parent or caregiver, as well as diapering, dressing, and undressing the infant; they should then be encouraged to practice immediately in the clinic or office.

During visits for harness adjustment, the strap position should be marked with indelible ink, allowing parents to reapply the device correctly, should removal be required (eg, for bathing).⁹ Ten percent of parents reportedly find reapplying the harness difficult during the first weeks of use. Difficulty in dressing and carrying an infant in a harness, feet slipping out of the harness, and skin irritation have been reported by about one-third of parents.¹⁹

Treatment adherence and subsequent success with the Pavlik harness is reported greatest (95%) in patients whose parents engage in demonstrations of harness use and follow instructions precisely.¹⁹ By providing a contact name and office number and following up with a phone call a few days after the harness is first applied, clinicians can significantly decrease parents’ anxiety and increase overall compliance.⁹

Conclusion
Despite recent increased awareness of DDH and the importance of thorough screening programs, hip dysplasia continues to be a frequently missed diagnosis in pediatrics. It is often up to the primary care clinician to screen for, assess, and potentially diagnose DDH. Therefore, a thorough understanding of this condition can promote early detection and diagnosis, with less invasive treatment and a more favorable outcome.

A proper hip examination should be a standard component of all newborn and infant well-child examinations. If DDH is suspected, appropriate referral to a pediatric orthopedic surgeon must be made so that timely treatment can be initiated. Early use of the Pavlik harness is significantly easier than the invasive surgery and prolonged immobilization necessitated by a delayed diagnosis. Whatever the course of treatment required, it is important for clinicians to support the patient and family: training and anticipatory guidance are essential components of DDH management.

A 5-day-old infant was referred to the pediatric orthopedic clinic for evaluation of a left hip “clunk.” She is a firstborn child, born at full term (39 weeks) via cesarean delivery secondary to breech presentation. Her weight at birth was 7 lb 6 oz. The infant was noted to have a left hip clunk during a routine physical examination by her pediatrician, who made a referral to the pediatric orthopedic clinic for possible hip dysplasia. This is the patient’s first visit to the clinic.

There is no family history of hip dysplasia or other orthopedic abnormalities. The infant is a well-appearing, alert female measuring 20.5” in length and weighing 7 lb 4 oz. Vital signs are stable with no abnormality detected. The heart is regular in rate and rhythm, and the chest is clear bilaterally.

No cutaneous abnormalities are noted. The patient is able to move all her extremities spontaneously, and her spine is straight and normal with no evidence of spinal dysraphism. Her feet are normal bilaterally, with full range of motion and no equinovarus or metatarsus adductus deformity.

The neurologic examination is also unremarkable, with normal neonatal reflexes and excellent muscle tone throughout. 

Examination of the infant’s hips reveals a positive result on the Barlow test on the left side (the hip can be dislocated). There is also a positive Ortolani sign (the hip can be reduced), with asymmetric thigh skin folds noted (see Figures 1A and 1B, respectively).

Based on these positive physical examination findings, the patient was diagnosed with developmental dysplasia of the hip (DDH). Initial ultrasonography to confirm the diagnosis was not considered necessary, as the physical examination demonstrated obvious instability.1 The infant was placed in a Pavlik harness, which her parents were instructed should be worn full-time (see Figures 2A and 2B). She was scheduled for weekly follow-up visits for adjustments to the harness and serial hip examinations.

At the second follow-up visit, ultrasonography was performed, confirming the presence of dysplasia with decreased femoral head coverage and a steep socket (acetabulum). Use of the Pavlik harness was continued full-time for six weeks.

At age 6 weeks, the infant underwent a follow-up ultrasound to assess for improvement in the degree of dysplasia. The test revealed normal hips bilaterally with no evidence of DDH. Therefore, use of the Pavlik harness was discontinued. The parents were instructed to bring the child back in six months for a repeat clinical examination and an anteroposterior x-ray of the pelvis.¹

Discussion
The term developmental dysplasia of the hip (DDH) has replaced the more traditional term congenital hip dislocation because DDH more accurately reflects the variable characteristics that can be seen with this condition. As DDH may not be present at birth, the term congenital is misleading. We now know that DDH may occur in utero, perinatally, or during infancy and childhood.^2,3

Generally, DDH is used to describe an abnormal relationship between the femoral head and the acetabulum (see Figure 3⁴). The term represents a wide spectrum of abnormality, as shown in the Graf classification of hips in infants: type I refers to a normal hip; type II, immature development to mild dysplasia; type III, subluxation of the femoral head; and type 4, frank dislocation with severe instability.⁵

Diagnosing and managing DDH correctly requires the clinician to have a thorough understanding of the normal growth and development that occurs in the hip joint. Embryologically, the joint (including the femoral head and acetabulum) develops from the same primitive mesenchymal cells.⁶ By 11 to 12 weeks’ gestation, the initial structures of the hip joint are fully formed; theoretically, this is the earliest time at which a dislocation can occur.^2,7 DDH that develops at this stage would be called teratologic; this condition is seen most frequently in patients who have underlying neuromuscular conditions, such as myelodysplasia (spina bifida) or arthrogryposis. A typical dislocation takes place during the perinatal period in an infant who is otherwise healthy.²

Etiology
DDH occurs in about 11 of every 1,000 infants, with frank dislocations occurring in one to two infants per 10,000.⁸ The left hip is involved in approximately 60% of cases, the right in 20%, and both hips in about 20%. In the most common intrauterine fetal position, the left hip is lower than the right (usually abutting the mother’s sacrum) and is often in adduction. This is likely the reason that the left hip is more commonly affected by DDH.

DDH is believed to be multifactorial, with physiologic, genetic, and mechanical factors implicated in the etiology.³ The incidence of DDH varies with factors such as the patient’s age, race, and gender, the experience and training of the examiner, and the diagnostic criteria that are used.

Known risk factors for a positive newborn screening are shown in the table.^9,10 It is often helpful for clinicians to remember the “4F” mnemonic associated with DDH: female, firstborn, foot first, and family history.⁹

There is also an increased risk for DDH in patients with other conditions that are associated with intrauterine crowding. These include congenital muscular torticollis, metatarsus adductus, and congenital dislocation of the knee.²

Physical Examination
All newborn infants should be screened for DDH as part of the initial physical examination, with ultrasonography recommended for infants deemed at high risk for DDH and for those with inconclusive results on examination.^1,10,11 Providers should be aware that the newborn hip examination requires a considerable amount of practice and expertise.

A thorough medical history should always be obtained first, including gestational age, presentation (breech vs vertex), type of delivery (cesarean vs vaginal), gender, birth order, family history of DDH, ligamentous laxity, or myopathy.⁸

The examining clinician begins by placing the infant on a firm, flat surface. The infant should be as relaxed as possible. Next, the clinician observes both lower extremities for asymmetric thigh or buttock skin folds. Bilateral DDH can be very difficult to diagnose on the basis of this examination due to the lack of asymmetry (hips will have symmetric abnormality).

The Galeazzi sign is elicited by placing the infant supine with the hips and knees flexed to 90°.¹² With the hips in neutral abduction, the provider should determine whether the knees are at the same height. Unequal knee heights—a positive result for the Galeazzi sign—suggest femoral shortening (apparent leg length discrepancy), which may be explained by a hip dislocation. If both hips are dislocated, a false-negative result will often occur, since both will appear short and there will be no discrepancy.^2,12

Among physical examination techniques, the Ortolani and Barlow maneuvers are considered most reliable to detect hip instability in newborns and infants younger than 6 months^2,13,14 (review Figures 1A and 1B). The Ortolani test is used to detect the sensation of the dislocated hip reducing into the acetabulum, and the Barlow test elicits the unstable hip dislocating.² A palpable and occasionally audible clunk is considered a positive result on the Barlow test and usually indicates a diagnosis of DDH.¹⁴ High-pitched clicks or snaps frequently occur with hip range-of-motion maneuvers and during Ortolani and Barlow testing. These sounds are often attributed to snapping of the iliotibial band over the greater trochanter and do not usually signify dysplasia.¹⁵

Because DDH is a dynamic and evolving process, the physical findings on clinical examination change significantly, depending on the age of the infant or child. As an infant approaches age 3 months, limited hip abduction (especially when asymmetric) is often the most reliable physical examination finding in patients with DDH.¹² After age 3 to 4 months, Ortolani and Barlow testing will often produce negative results as progressive soft tissue contractures evolve.

Once a child begins to walk, gait abnormalities (eg, a short-limbed or waddling gait pattern) may raise suspicion for a diagnosis of DDH.⁷ It has been recommended that evaluation for DDH be performed at each routine office examination until the child is 12 months of age.¹

Treatment
The Pavlik harness is considered first-line treatment for DDH in infants younger than 6 months. The harness is a dynamic splint that allows the infant to engage in a sphere of active motion that encourages stabilization and deepening of the socket. The harness is applied with the knees flexed to about 90° and the hips in about 70° of abduction and 100° to 110° of flexion (as shown in Figures 2A and 2B).⁹

The duration of treatment depends on the infant’s age at presentation and the severity of DDH. Progress is judged by serial examinations and dynamic ultrasounds. The harness is worn full-time until clinical and radiographic examinations both yield normal results. After six weeks of treatment, the hips are examined out of the harness, and a repeat ultrasound is usually obtained. If findings are normal, use of the harness is ordinarily discontinued. Some patients will require harness use for a longer period in cases of delayed development of the acetabulum and/or severe laxity of the ligaments.⁹

The Pavlik harness is successful more than 90% of the time in newborns with DDH.⁸ Success rates have been reported as greatest in infants younger than 8 weeks at the time of treatment initiation, those with only one affected hip, and those with less severe disease (Graf types II or III).¹⁶

If ultrasonography shows no improvement after two to three weeks, it is usually recommended that the harness be discontinued; most orthopedic surgeons will then proceed with a closed or open reduction and spica body casting. Similarly, when the diagnosis of DDH is delayed until after ages 6 to 8 months, a closed reduction under anesthesia and placement of a spica body cast is usually the recommended treatment to maintain the hip in the reduced position.^17,18 Some older children (ages 1 to 5 years) may require bracing, traction, open reduction, and/or femoral or pelvic osteotomy.^17,18 It is believed that undiagnosed, untreated DDH can lead to early-onset degenerative hip disease (arthritis).¹

Patient/Family Education
The Pavlik harness is most effective when a consistent support system exists to educate parents about the importance of the harness, its care and maintenance, and the consequences of failure. Close monitoring of the infant’s progress is also essential to promoting adherence. Application and removal of the harness should be demonstrated to the parent or caregiver, as well as diapering, dressing, and undressing the infant; they should then be encouraged to practice immediately in the clinic or office.

During visits for harness adjustment, the strap position should be marked with indelible ink, allowing parents to reapply the device correctly, should removal be required (eg, for bathing).⁹ Ten percent of parents reportedly find reapplying the harness difficult during the first weeks of use. Difficulty in dressing and carrying an infant in a harness, feet slipping out of the harness, and skin irritation have been reported by about one-third of parents.¹⁹

Treatment adherence and subsequent success with the Pavlik harness is reported greatest (95%) in patients whose parents engage in demonstrations of harness use and follow instructions precisely.¹⁹ By providing a contact name and office number and following up with a phone call a few days after the harness is first applied, clinicians can significantly decrease parents’ anxiety and increase overall compliance.⁹

Conclusion
Despite recent increased awareness of DDH and the importance of thorough screening programs, hip dysplasia continues to be a frequently missed diagnosis in pediatrics. It is often up to the primary care clinician to screen for, assess, and potentially diagnose DDH. Therefore, a thorough understanding of this condition can promote early detection and diagnosis, with less invasive treatment and a more favorable outcome.

A proper hip examination should be a standard component of all newborn and infant well-child examinations. If DDH is suspected, appropriate referral to a pediatric orthopedic surgeon must be made so that timely treatment can be initiated. Early use of the Pavlik harness is significantly easier than the invasive surgery and prolonged immobilization necessitated by a delayed diagnosis. Whatever the course of treatment required, it is important for clinicians to support the patient and family: training and anticipatory guidance are essential components of DDH management.

A 5-day-old infant was referred to the pediatric orthopedic clinic for evaluation of a left hip “clunk.” She is a firstborn child, born at full term (39 weeks) via cesarean delivery secondary to breech presentation. Her weight at birth was 7 lb 6 oz. The infant was noted to have a left hip clunk during a routine physical examination by her pediatrician, who made a referral to the pediatric orthopedic clinic for possible hip dysplasia. This is the patient’s first visit to the clinic.

There is no family history of hip dysplasia or other orthopedic abnormalities. The infant is a well-appearing, alert female measuring 20.5” in length and weighing 7 lb 4 oz. Vital signs are stable with no abnormality detected. The heart is regular in rate and rhythm, and the chest is clear bilaterally.

No cutaneous abnormalities are noted. The patient is able to move all her extremities spontaneously, and her spine is straight and normal with no evidence of spinal dysraphism. Her feet are normal bilaterally, with full range of motion and no equinovarus or metatarsus adductus deformity.

The neurologic examination is also unremarkable, with normal neonatal reflexes and excellent muscle tone throughout. 

Examination of the infant’s hips reveals a positive result on the Barlow test on the left side (the hip can be dislocated). There is also a positive Ortolani sign (the hip can be reduced), with asymmetric thigh skin folds noted (see Figures 1A and 1B, respectively).

Based on these positive physical examination findings, the patient was diagnosed with developmental dysplasia of the hip (DDH). Initial ultrasonography to confirm the diagnosis was not considered necessary, as the physical examination demonstrated obvious instability.1 The infant was placed in a Pavlik harness, which her parents were instructed should be worn full-time (see Figures 2A and 2B). She was scheduled for weekly follow-up visits for adjustments to the harness and serial hip examinations.

At the second follow-up visit, ultrasonography was performed, confirming the presence of dysplasia with decreased femoral head coverage and a steep socket (acetabulum). Use of the Pavlik harness was continued full-time for six weeks.

At age 6 weeks, the infant underwent a follow-up ultrasound to assess for improvement in the degree of dysplasia. The test revealed normal hips bilaterally with no evidence of DDH. Therefore, use of the Pavlik harness was discontinued. The parents were instructed to bring the child back in six months for a repeat clinical examination and an anteroposterior x-ray of the pelvis.¹

Discussion
The term developmental dysplasia of the hip (DDH) has replaced the more traditional term congenital hip dislocation because DDH more accurately reflects the variable characteristics that can be seen with this condition. As DDH may not be present at birth, the term congenital is misleading. We now know that DDH may occur in utero, perinatally, or during infancy and childhood.^2,3

Generally, DDH is used to describe an abnormal relationship between the femoral head and the acetabulum (see Figure 3⁴). The term represents a wide spectrum of abnormality, as shown in the Graf classification of hips in infants: type I refers to a normal hip; type II, immature development to mild dysplasia; type III, subluxation of the femoral head; and type 4, frank dislocation with severe instability.⁵

Diagnosing and managing DDH correctly requires the clinician to have a thorough understanding of the normal growth and development that occurs in the hip joint. Embryologically, the joint (including the femoral head and acetabulum) develops from the same primitive mesenchymal cells.⁶ By 11 to 12 weeks’ gestation, the initial structures of the hip joint are fully formed; theoretically, this is the earliest time at which a dislocation can occur.^2,7 DDH that develops at this stage would be called teratologic; this condition is seen most frequently in patients who have underlying neuromuscular conditions, such as myelodysplasia (spina bifida) or arthrogryposis. A typical dislocation takes place during the perinatal period in an infant who is otherwise healthy.²

Etiology
DDH occurs in about 11 of every 1,000 infants, with frank dislocations occurring in one to two infants per 10,000.⁸ The left hip is involved in approximately 60% of cases, the right in 20%, and both hips in about 20%. In the most common intrauterine fetal position, the left hip is lower than the right (usually abutting the mother’s sacrum) and is often in adduction. This is likely the reason that the left hip is more commonly affected by DDH.

DDH is believed to be multifactorial, with physiologic, genetic, and mechanical factors implicated in the etiology.³ The incidence of DDH varies with factors such as the patient’s age, race, and gender, the experience and training of the examiner, and the diagnostic criteria that are used.

Known risk factors for a positive newborn screening are shown in the table.^9,10 It is often helpful for clinicians to remember the “4F” mnemonic associated with DDH: female, firstborn, foot first, and family history.⁹

There is also an increased risk for DDH in patients with other conditions that are associated with intrauterine crowding. These include congenital muscular torticollis, metatarsus adductus, and congenital dislocation of the knee.²

Physical Examination
All newborn infants should be screened for DDH as part of the initial physical examination, with ultrasonography recommended for infants deemed at high risk for DDH and for those with inconclusive results on examination.^1,10,11 Providers should be aware that the newborn hip examination requires a considerable amount of practice and expertise.

A thorough medical history should always be obtained first, including gestational age, presentation (breech vs vertex), type of delivery (cesarean vs vaginal), gender, birth order, family history of DDH, ligamentous laxity, or myopathy.⁸

The examining clinician begins by placing the infant on a firm, flat surface. The infant should be as relaxed as possible. Next, the clinician observes both lower extremities for asymmetric thigh or buttock skin folds. Bilateral DDH can be very difficult to diagnose on the basis of this examination due to the lack of asymmetry (hips will have symmetric abnormality).

The Galeazzi sign is elicited by placing the infant supine with the hips and knees flexed to 90°.¹² With the hips in neutral abduction, the provider should determine whether the knees are at the same height. Unequal knee heights—a positive result for the Galeazzi sign—suggest femoral shortening (apparent leg length discrepancy), which may be explained by a hip dislocation. If both hips are dislocated, a false-negative result will often occur, since both will appear short and there will be no discrepancy.^2,12

Among physical examination techniques, the Ortolani and Barlow maneuvers are considered most reliable to detect hip instability in newborns and infants younger than 6 months^2,13,14 (review Figures 1A and 1B). The Ortolani test is used to detect the sensation of the dislocated hip reducing into the acetabulum, and the Barlow test elicits the unstable hip dislocating.² A palpable and occasionally audible clunk is considered a positive result on the Barlow test and usually indicates a diagnosis of DDH.¹⁴ High-pitched clicks or snaps frequently occur with hip range-of-motion maneuvers and during Ortolani and Barlow testing. These sounds are often attributed to snapping of the iliotibial band over the greater trochanter and do not usually signify dysplasia.¹⁵

Because DDH is a dynamic and evolving process, the physical findings on clinical examination change significantly, depending on the age of the infant or child. As an infant approaches age 3 months, limited hip abduction (especially when asymmetric) is often the most reliable physical examination finding in patients with DDH.¹² After age 3 to 4 months, Ortolani and Barlow testing will often produce negative results as progressive soft tissue contractures evolve.

Once a child begins to walk, gait abnormalities (eg, a short-limbed or waddling gait pattern) may raise suspicion for a diagnosis of DDH.⁷ It has been recommended that evaluation for DDH be performed at each routine office examination until the child is 12 months of age.¹

Treatment
The Pavlik harness is considered first-line treatment for DDH in infants younger than 6 months. The harness is a dynamic splint that allows the infant to engage in a sphere of active motion that encourages stabilization and deepening of the socket. The harness is applied with the knees flexed to about 90° and the hips in about 70° of abduction and 100° to 110° of flexion (as shown in Figures 2A and 2B).⁹

The duration of treatment depends on the infant’s age at presentation and the severity of DDH. Progress is judged by serial examinations and dynamic ultrasounds. The harness is worn full-time until clinical and radiographic examinations both yield normal results. After six weeks of treatment, the hips are examined out of the harness, and a repeat ultrasound is usually obtained. If findings are normal, use of the harness is ordinarily discontinued. Some patients will require harness use for a longer period in cases of delayed development of the acetabulum and/or severe laxity of the ligaments.⁹

The Pavlik harness is successful more than 90% of the time in newborns with DDH.⁸ Success rates have been reported as greatest in infants younger than 8 weeks at the time of treatment initiation, those with only one affected hip, and those with less severe disease (Graf types II or III).¹⁶

If ultrasonography shows no improvement after two to three weeks, it is usually recommended that the harness be discontinued; most orthopedic surgeons will then proceed with a closed or open reduction and spica body casting. Similarly, when the diagnosis of DDH is delayed until after ages 6 to 8 months, a closed reduction under anesthesia and placement of a spica body cast is usually the recommended treatment to maintain the hip in the reduced position.^17,18 Some older children (ages 1 to 5 years) may require bracing, traction, open reduction, and/or femoral or pelvic osteotomy.^17,18 It is believed that undiagnosed, untreated DDH can lead to early-onset degenerative hip disease (arthritis).¹

Patient/Family Education
The Pavlik harness is most effective when a consistent support system exists to educate parents about the importance of the harness, its care and maintenance, and the consequences of failure. Close monitoring of the infant’s progress is also essential to promoting adherence. Application and removal of the harness should be demonstrated to the parent or caregiver, as well as diapering, dressing, and undressing the infant; they should then be encouraged to practice immediately in the clinic or office.

During visits for harness adjustment, the strap position should be marked with indelible ink, allowing parents to reapply the device correctly, should removal be required (eg, for bathing).⁹ Ten percent of parents reportedly find reapplying the harness difficult during the first weeks of use. Difficulty in dressing and carrying an infant in a harness, feet slipping out of the harness, and skin irritation have been reported by about one-third of parents.¹⁹

Treatment adherence and subsequent success with the Pavlik harness is reported greatest (95%) in patients whose parents engage in demonstrations of harness use and follow instructions precisely.¹⁹ By providing a contact name and office number and following up with a phone call a few days after the harness is first applied, clinicians can significantly decrease parents’ anxiety and increase overall compliance.⁹

Conclusion
Despite recent increased awareness of DDH and the importance of thorough screening programs, hip dysplasia continues to be a frequently missed diagnosis in pediatrics. It is often up to the primary care clinician to screen for, assess, and potentially diagnose DDH. Therefore, a thorough understanding of this condition can promote early detection and diagnosis, with less invasive treatment and a more favorable outcome.

A proper hip examination should be a standard component of all newborn and infant well-child examinations. If DDH is suspected, appropriate referral to a pediatric orthopedic surgeon must be made so that timely treatment can be initiated. Early use of the Pavlik harness is significantly easier than the invasive surgery and prolonged immobilization necessitated by a delayed diagnosis. Whatever the course of treatment required, it is important for clinicians to support the patient and family: training and anticipatory guidance are essential components of DDH management.