Spectrum of hip instability ranging from mild acetabular dysplasia to frank dislocation in infants.
Also known as: DDH, developmental dysplasia of the hip, congenital hip dysplasia, CHD
Overview
A spectrum of disorders involving abnormal development of the hip joint in which the femoral head and acetabulum fail to form a stable concentric relationship. Ranges from mild acetabular dysplasia to subluxation to frank dislocation.
Epidemiology
Incidence of frank dislocation approximately 1 in 1,000 live births; milder hip instability detectable in 1-3 percent of newborns. Female-to-male ratio approximately 4-6:1. Left hip more commonly involved than right; bilateral in 20 percent.
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Question 1MusculoskeletalMedium
A 6-week-old girl is brought to clinic for a routine visit. She was born in the frank breech position to a primigravid mother, and her older sister was treated for a hip problem in infancy. On examination, gentle abduction of the flexed left hip with anterior pressure on the greater trochanter produces a palpable clunk, and abduction of that hip is mildly limited compared with the right. The remainder of the examination is normal. Which of the following is the most appropriate next diagnostic test?
AMR imaging of the hips
BArthrography of the hips
CRadiograph of the pelvis
DUltrasound of the hips
Reveal answer & full explanation
Correct answer: D — Ultrasound of the hips
AMR imaging of the hips
BArthrography of the hips
CRadiograph of the pelvis
DUltrasound of the hips✓
Why Ultrasound of the hips is correct
This 6-week-old has a positive Ortolani sign (clunk on reduction) plus multiple risk factors (female, frank breech, first-degree family history, firstborn), making developmental dysplasia of the hip (DDH) the leading concern.
Before 4-6 months of age the femoral head is largely cartilaginous and not yet ossified, so it is poorly seen on plain films; ultrasound directly images the cartilaginous femoral head and acetabulum and is the preferred study at this age.
Ultrasound also allows Graf classification using the alpha (bony roof) and beta (cartilaginous roof) angles to grade dysplasia and guide treatment.
The AAP recommends hip ultrasound at approximately 6 weeks for high-risk infants (breech delivery, positive family history) and to evaluate an abnormal newborn hip exam.
Why the others are wrong
Radiograph of the pelvis: the preferred study only after about 4-6 months, once the ossific nucleus of the femoral head appears; at 6 weeks it is largely uninformative because the head is not yet ossified.
MR imaging of the hips: reserved for confirming concentric reduction after closed or open reduction, not for initial diagnosis, and it generally requires sedation in an infant.
Arthrography of the hips — an invasive contrast study performed under anesthesia in the operating room to confirm concentric reduction and define an inverted limbus during closed or open reduction; it is a treatment-guidance tool, not the initial noninvasive test for a reducible hip found on a screening exam.
Question 2MusculoskeletalMedium
A 5-week-old girl born in the frank breech position is brought in for a well-child visit. On examination, gentle flexion and abduction of the left hip with anterior pressure on the greater trochanter (Ortolani maneuver) produces a palpable clunk as the femoral head reduces, and a Barlow maneuver reproducibly dislocates the hip. Hip ultrasound shows a shallow left acetabulum with a reducible, subluxated femoral head. Which of the following is the most appropriate initial management?
ADouble-diaper abduction splinting
BApplication of a Pavlik harness
CObservation with repeat ultrasound
DClosed reduction and spica casting
Reveal answer & full explanation
Correct answer: B — Application of a Pavlik harness
ADouble-diaper abduction splinting
BApplication of a Pavlik harness✓
CObservation with repeat ultrasound
DClosed reduction and spica casting
Why Application of a Pavlik harness is correct
For a reducible dislocated or subluxated hip in an infant under 6 months, the Pavlik harness is the guideline-defined first-line therapy (AAP).
It holds the hips in flexion (90-100 degrees) and gentle abduction, directing the femoral head into the acetabulum so the shallow socket can remodel; it is worn 23 hours a day with weekly follow-up.
Success rates are 80-95% for reducible hips in young infants, and forced abduction is avoided to prevent avascular necrosis or femoral nerve palsy.
Why the others are wrong
Closed reduction and spica casting: second-line, reserved for infants about 6-18 months or after a failed Pavlik trial, not for an initial presentation in a young, harness-eligible infant.
Double-diaper abduction splinting — double or triple diapering delivers no reliable, sustained abduction and is not an accepted treatment for a frankly unstable hip; a Barlow-positive, subluxated hip requires a Pavlik harness with monitored positioning and serial ultrasound.
Observation with repeat ultrasound: appropriate for physiologic immaturity (Graf IIa) with a stable hip, but this hip is frankly unstable on Barlow and subluxated, so delaying treatment risks fixed dislocation.
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Combination of ligamentous laxity (maternal hormonal influence), abnormal mechanical forces in utero, and acetabular morphology. A shallow acetabulum cannot retain the femoral head, allowing subluxation or dislocation. Persistent malposition leads to remodeling abnormalities — false acetabulum, hypertrophied labrum (limbus), and tight psoas, all of which become barriers to reduction.
Clinical presentation
Symptoms
Often asymptomatic in newborns; identified on screening
Older infant (>3 months): asymmetric thigh or gluteal skin folds, limited hip abduction
Toddler: delayed walking, Trendelenburg gait, leg length discrepancy
Bilateral dislocation may present with waddling gait and exaggerated lumbar lordosis
Signs / physical exam
Ortolani maneuver (reduction): hip flexed and gently abducted with anterior pressure on the greater trochanter — palpable clunk as femoral head reduces into acetabulum
Barlow maneuver (dislocation): hip flexed and adducted with posterior pressure on the knee — palpable clunk as femoral head exits the acetabulum
Galeazzi sign: with hips and knees flexed, knees are at unequal heights (the dislocated side appears shorter)
Limited hip abduction in older infants
Asymmetric thigh and inguinal skin folds
Classic findings
Female infant with a positive Ortolani clunk on examination, or an older infant with asymmetric thigh folds, limited abduction, and a positive Galeazzi sign.
Differential diagnosis
Coxa vara congenita — Decreased femoral neck-shaft angle; identified later in childhood with limp
Proximal femoral focal deficiency — Major deficiency of the proximal femur on imaging; obvious limb length discrepancy
Neuromuscular hip dislocation (cerebral palsy, spina bifida) — Identified in the setting of known neuromuscular disease, usually progressive
Septic arthritis of the hip — Acute onset, fever, refusal to move limb, elevated inflammatory markers
Transient hip click without instability — High-pitched click without instability on Ortolani/Barlow; usually benign
Diagnostic workup
Diagnostic criteria
Graf classification by ultrasound uses alpha (bony roof) and beta (cartilaginous roof) angles. Type I — alpha ≥60 degrees, normal; Type IIa — physiologic immaturity <3 months, alpha 50-59; Type IIb — pathologic at >3 months; Type III — subluxated; Type IV — dislocated. On radiographs, the femoral head should lie within the lower inner quadrant of Hilgenreiner and Perkins lines.
Labs
None required
Imaging
Ultrasound of the hips — gold standard before 4-6 months of age (femoral head is not yet ossified)
Plain radiographs (AP pelvis) — preferred after 4-6 months when the ossific nucleus is visible
MRI or CT post-reduction to confirm concentric reduction
AAP recommends ultrasound at 6 weeks for high-risk infants (breech delivery, family history); routine universal ultrasound is not endorsed
Diagnostic algorithm
Age
Best Examination Finding
Preferred Imaging
Initial Treatment
Newborn-3 mo
Ortolani / Barlow clunk
Ultrasound at 6 wk if high risk
Pavlik harness
3-6 mo
Limited abduction, asymmetric folds
Ultrasound
Pavlik harness
6-18 mo
Galeazzi sign, limited abduction
AP pelvis radiograph
Closed reduction and spica
>18 mo
Limp, Trendelenburg gait
AP pelvis radiograph
Open reduction ± osteotomy
Age-based approach to detection and initial management of DDH.
Treatment
First-line
Pavlik harness for infants <6 months — maintains flexion 90-100 degrees and abduction to promote concentric reduction; worn 23 hours per day with weekly follow-up
Success rate of Pavlik harness is 80-95 percent for reducible dislocations in young infants
Avoid forced abduction (femoral nerve palsy or AVN from over-aggressive positioning)
Second-line / adjunct
Closed reduction under anesthesia with arthrogram and spica casting for failed Pavlik or older infants (6-18 months)
Open reduction with capsulorrhaphy and possible femoral and/or pelvic osteotomy for older children or failed closed reduction
Salvage osteotomy (Salter, Pemberton, periacetabular) for residual dysplasia in older children and adolescents
Complications
Avascular necrosis of the femoral head (most feared complication of treatment, especially with forced abduction)
Redislocation after reduction
Residual acetabular dysplasia with progressive subluxation
Early hip osteoarthritis in adulthood (dysplasia is a leading cause of total hip arthroplasty in young adults)
Limb length discrepancy
PANCE pearls
Ortolani and Barlow maneuvers are most reliable in the first weeks to months of life; after 3 months, the dislocated hip becomes harder to reduce and limited abduction becomes the dominant finding.
Ultrasound is preferred before 4-6 months; plain radiographs after the ossific nucleus appears.
Untreated DDH is the leading cause of early-onset hip osteoarthritis in young adults.
The Pavlik harness is contraindicated in stiff, irreducible hips and in infants over 6 months.
References
AAP 2016 — American Academy of Pediatrics clinical report on evaluation and referral for developmental dysplasia of the hip in infants
POSNA — Pediatric Orthopaedic Society of North America clinical resources on DDH
AAOS 2014 — American Academy of Orthopaedic Surgeons clinical practice guideline on detection and nonoperative management of pediatric DDH
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