Femoral Neck Stress Fracture
This presentation is most consistent with a femoral neck stress fracture (option e). The combination of progressive anterior hip pain in a high-impact athlete, painful limited internal rotation, pain with hopping, and absence of tenderness or weakness is classic for this diagnosis 1, 2.
Clinical Reasoning
Key Diagnostic Features Present
- Progressive anterior hip pain with weight-bearing: The evolution from end-of-day pain to constant weight-bearing pain with limping indicates worsening bone stress 3, 2
- Painful limited internal rotation: This is the hallmark physical examination finding for femoral neck stress fractures, as internal rotation stresses the femoral neck 1, 4
- Pain with hopping test: Single-leg hop test is highly sensitive for detecting femoral neck stress injuries by loading the hip through the femoral neck 2
- No tenderness to palpation: Femoral neck stress fractures cause deep groin pain but no superficial tenderness, distinguishing them from soft tissue injuries 1, 3
- High-risk occupation: Aerobic dance instructors perform repetitive high-impact loading, a known risk factor for femoral neck stress fractures 5, 4
Why Other Options Are Incorrect
- Greater trochanter pain syndrome (a): Would cause lateral hip pain with tenderness over the greater trochanter on palpation, not anterior hip pain with painful internal rotation 1
- Piriformis syndrome (b): Presents with buttock pain radiating down the posterior thigh, not anterior hip pain, and would show pain with resisted external rotation and abduction 1
- Torn external oblique with ilioinguinal nerve entrapment (c): Would cause superficial groin pain with palpable tenderness and pain with trunk rotation/flexion, not deep hip pain with internal rotation 1
- Osteitis pubis (d): Causes midline pubic symphysis pain and tenderness, not lateral anterior hip pain, and typically presents with adductor pain on resistance testing 1
Critical Management Considerations
Immediate Diagnostic Approach
- Start with plain radiographs of the hip (AP and frog-leg lateral views) as first-line imaging, though sensitivity is only 15-35% initially 1, 5
- Proceed immediately to MRI without contrast if radiographs are negative or equivocal—this is the definitive test with excellent sensitivity and can detect bone marrow edema before fracture lines develop 1, 5
- Do not delay MRI in this high-risk scenario: Femoral neck stress fractures are classified as high-risk injuries with devastating consequences if diagnosis is delayed, including displacement, nonunion, and avascular necrosis 1, 4, 2
Why This Is Urgent
Femoral neck stress fractures have catastrophic potential if missed. Tension-side (superolateral) fractures are inherently unstable and prone to displacement, requiring surgical stabilization 1, 6. Even compression-side (inferomedial) fractures can progress to completion if weight-bearing continues 4, 2. Delayed diagnosis significantly increases morbidity and impairs return to sport 2.
Common Pitfall to Avoid
Do not rely on clinical examination alone to rule out femoral neck stress fracture. Hip examination tests have good sensitivity but poor specificity and cannot reliably distinguish hip-related pain from other causes 1. The absence of palpable tenderness does not exclude this diagnosis—femoral neck stress fractures characteristically lack superficial tenderness 1, 3.
Treatment Implications
- Compression-side fractures: Non-weight-bearing for 6-8 weeks with gradual return to activity 6, 7
- Tension-side fractures: Require surgical stabilization to prevent displacement 1, 6
- Trabecular stress injuries (femoral neck): Associated with longer time to return to sport compared to cortical bone stress injuries 5