How should a teenager with bilateral hip pain be evaluated and initially managed?

Bilateral Hip Pain in a Teenager: Evaluation and Management

Start with anteroposterior (AP) pelvis and lateral femoral head-neck radiographs as your initial imaging, combined with a focused clinical examination including the FADIR test, to screen for the most common causes of bilateral hip pain in adolescents including femoroacetabular impingement (FAI) syndrome, acetabular dysplasia, and slipped capital femoral epiphysis (SCFE). 1

Initial Clinical Assessment

Key History Elements to Obtain

• Activity-related symptoms: Pain worsening with activity, discomfort when seated, difficulty rising from sitting, or trouble with stairs suggests mechanical hip pathology 2
• Bilateral presentation: Consider systemic causes (inflammatory conditions) versus bilateral structural abnormalities (FAI, dysplasia)
• Acute versus insidious onset: Sudden onset with trauma requires different workup than gradual onset
• Constitutional symptoms: Fever, weight loss, or night pain raises concern for infection or neoplasm 3, 4

Critical Physical Examination Findings

• FADIR test (Flexion-Adduction-Internal Rotation): A negative test helps rule out hip-related pain; this is the only clinical test with sufficient evidence for screening 1
• Obligate external rotation during hip flexion: This finding is concerning for SCFE and requires urgent imaging 2
• Trendelenburg gait: Suggests hip instability from acetabular dysplasia 2
• Screen the spine and pelvis: Hip pain may be referred from lumbar spine or pelvic pathology 1

Important caveat: Most special tests (Thomas test, prone instability test) have very limited diagnostic accuracy and are not recommended for diagnosis 1. Range of motion and muscle performance tests also lack diagnostic accuracy 1.

Initial Imaging Strategy

First-Line Imaging: Plain Radiographs

Obtain AP pelvis and lateral femoral head-neck views (Dunn, frog-leg, or cross-table lateral) as your initial imaging. 1 This approach:

• Screens for common structural abnormalities (FAI morphology, dysplasia, SCFE)
• Evaluates bilateral hip symmetry
• Rules out serious pathology (tumors, fractures)
• Guides need for advanced imaging

The 2020 International Hip-Related Pain Research Network consensus strongly recommends this approach (median score 9/9) 1. The 2017 ACR Appropriateness Criteria similarly endorses radiographs as the first test in most cases 5.

When to Add Advanced Imaging

Never use imaging alone to diagnose the cause of hip pain—always integrate with clinical findings. 1 Imaging has limited diagnostic utility with only small to moderate shifts in post-test probability even when positive 1.

Consider MRI/MRA or CT when:

• Three-dimensional morphological assessment is needed
• Evaluating intra-articular structures (labrum, cartilage, ligamentum teres) 1
• Radiographs are negative but clinical suspicion remains high
• Concern for stress fractures, osteonecrosis, or neoplasm 5

Critical finding from recent research: In adolescents with hip pain, extraarticular causes (apophysitis, stress reactions, tendinitis) are more common than intraarticular pathology (28.6% vs 20%), and 42.9% have no identifiable cause on imaging 6. This supports starting with non-contrast MRI rather than MR arthrography in most cases.

Diagnostic Categories After Imaging

Once imaging is obtained, categorize bilateral hip pain into 1:

1. FAI syndrome: Cam or pincer morphology with symptoms
2. Acetabular dysplasia/hip instability: Undercoverage of femoral head
3. Other conditions: Labral tears, cartilage defects, ligamentum teres pathology, or soft-tissue conditions without specific bony morphology

Common pitfall: Incidental findings (labral tears, cartilage changes) are common in asymptomatic adolescents and should not automatically be considered the pain source 1. Correlation with clinical presentation is essential.

Red Flags Requiring Urgent Evaluation

• Obligate external rotation with hip flexion: SCFE until proven otherwise—obtain AP pelvis and frog-leg lateral immediately 2
• Fever or signs of infection: Consider septic arthritis or osteomyelitis—ultrasound can rapidly detect effusion 7
• Night pain, weight loss, or constitutional symptoms: Concern for neoplasm—MRI indicated 5, 4
• Acute trauma with inability to bear weight: Rule out fracture or dislocation 8

Initial Management Approach

While definitive treatment depends on the specific diagnosis:

• Symptomatic borderline dysplasia: Trial of nonoperative management first 9
• Confirmed structural abnormalities with failed conservative care: Consider surgical consultation (periacetabular osteotomy for dysplasia, arthroscopy for FAI with labral pathology) 9
• No structural abnormality identified: Focus on activity modification, physical therapy, and reassessment

The bilateral nature of symptoms should prompt consideration of systemic inflammatory conditions if structural causes are excluded, though this is less common than bilateral structural abnormalities in active adolescents 10, 3.