What is the approach to managing an 8-year-old girl presenting with a Trendelenburg sign, indicating hip abductor weakness?

Approach to Trendelenburg Sign in an 8-Year-Old Girl

An 8-year-old girl with a Trendelenburg sign requires immediate evaluation for developmental dysplasia of the hip (DDH) as the primary concern, with pelvic radiography as the initial imaging study, followed by referral to pediatric orthopedic surgery for definitive management. 1

Initial Clinical Assessment

At 8 years of age, the Trendelenburg sign indicates hip abductor weakness, most commonly from DDH that was either missed in infancy or has progressed despite earlier screening. 1

Key physical examination findings to document:

• Limited hip abduction is the most critical finding in children over 3 months, as the Ortolani and Barlow maneuvers lose sensitivity after this age 1, 2
• Gait abnormalities: Look for antalgic gait (shortened support phase on affected side), toe-walking on the affected side to compensate, or waddling gait with increased lumbar lordosis if bilateral 1, 3
• Leg length discrepancy: Evaluate with the Galeazzi sign (patient supine with hips and knees flexed) to assess for shortening on the affected side 3
• Asymmetric skin folds in the proximal thigh, though this has low specificity 1, 3

Imaging Strategy

Pelvic radiography is the appropriate initial imaging study for an 8-year-old, as the femoral head ossification center is well-established by this age, making radiographs reliable for assessing hip morphology. 1

Obtain anteroposterior pelvis radiograph in neutral position to evaluate:

• Relationship of the femoral head to the acetabulum 1
• Acetabular roof orientation (should not be vertically oriented) 1
• Delayed appearance or eccentric positioning of the femoral head ossific nucleus 1
• Adaptive changes in the hip joint and proximal femur 1

Ultrasound is NOT recommended at this age, as it is primarily useful before 4-6 months when the femoral heads are cartilaginous. 1

Advanced imaging considerations:

• MRI without IV contrast may be appropriate if radiographs suggest soft tissue pathology affecting the hip abductors, such as tendon injury or muscle atrophy 1
• MRI can identify abductor tendon defects and fatty atrophy of the gluteus medius and minimus muscles 1

Differential Diagnosis Considerations

While DDH is the primary concern in this age group with Trendelenburg sign, also consider:

• Perthes disease (osteochondritis of the femoral head) - common in this age group 1
• Neuromuscular conditions causing hip abductor weakness (cerebral palsy, spina bifida, muscular dystrophy) 1
• Slipped capital femoral epiphysis - though more common in adolescents 1

Referral and Management

Immediate referral to pediatric orthopedic surgery is indicated for any child with suspected DDH, hip abductor weakness, or Trendelenburg sign. 1

Critical pitfalls to avoid:

• Do not rely solely on asymmetric skin folds, as they lack specificity for DDH 1, 3
• Do not confuse a stable "clicking" hip (benign) with true instability requiring intervention 2
• Do not delay imaging or referral, as late presentation is a major negative prognostic factor requiring more complex treatment and surgical intervention 1

Prognosis and Long-term Implications

Untreated or late-diagnosed DDH leads to:

• Early degenerative joint disease 1, 2
• DDH accounts for up to one-third of total hip arthroplasties in patients under 60 years of age 1
• Lifelong disability and early arthritis from untreated subluxation or dislocation 2

Treatment complications to monitor:

• Avascular necrosis is the most serious complication and predictor of poor prognosis 1, 2