Physical Examination Findings in Avascular Necrosis of the Hip
The most characteristic physical examination findings in avascular necrosis (AVN) of the hip are pain reproduced with internal rotation of the hip, antalgic gait, and restricted range of motion—particularly limited hip abduction—though physical examination has poor sensitivity for early-stage disease and cannot reliably exclude AVN.
Key Physical Examination Findings
Primary Findings
- Pain with internal rotation: This is the most consistent finding that reproduces the patient's chief complaint 1
- Antalgic gait: Patients characteristically walk with a limp to offload the affected hip 1
- Restricted range of motion: Particularly limited hip abduction, which becomes more prominent as disease progresses 1
- Negative pain with small-arc range of motion: Interestingly, patients often deny pain with gentle, small movements 1
Secondary Findings
- Quadriceps and gluteal muscle atrophy: Present in 100% of late-stage cases 2
- Limb length discrepancy/shortened limb: Common in advanced disease 2
- Trendelenburg sign: May be present, particularly in severe cases 3
- Pain with palpation: Generally absent over the greater trochanter 1
- Giving-way sensation: Patients may report hip instability with weight-bearing 4
Critical Limitations of Physical Examination
Physical examination has severely limited diagnostic utility for AVN, particularly in early stages. A prospective study of 176 HIV-infected patients demonstrated that:
- Sensitivity of individual tests: 0-50% (extremely poor)
- Specificity: 67-92% (moderate)
- Positive predictive value: <17% (very poor)
- Negative predictive value: >90% (good)
- Even combining all physical examination maneuvers yielded only 88% sensitivity with 34% specificity 5
Clinical Implications
A negative physical examination does NOT exclude AVN 5. However, positive findings should prompt immediate MRI evaluation based on overall clinical suspicion 5, 6.
Pain Characteristics to Elicit in History
- Location: Deep groin, lateral hip, or buttock pain 1, 6
- Pattern: Dull, constant ache that sharpens with weight-bearing 7
- Timing: Exacerbated by activity, may worsen at night 6
- Progression: Typically progressive over months to years 1
- Radiation: May radiate to groin, back, or thigh 6
Diagnostic Approach
When AVN is clinically suspected based on persistent hip pain with the above physical findings, proceed directly to MRI—do not rely on physical examination or plain radiographs to exclude the diagnosis 8, 9, 10.
- Plain radiographs: Obtain initially to exclude fracture, tumor, or primary arthritis, but they are insensitive for early AVN 10, 6
- MRI: The gold standard for diagnosis, required for patients with persistent hip pain and normal radiographs 8, 9, 10, 6
- Image both hips: Bilateral involvement is common (60% of cases in one study) 5
Common Pitfall
The most dangerous error is dismissing AVN based on equivocal physical examination and radiographic findings 6. In any patient with persistent hip pain—especially those with risk factors (corticosteroid use, alcohol abuse, HIV infection, hemoglobinopathies)—maintain high clinical suspicion and proceed to MRI even when physical examination is unremarkable 8, 9, 5, 6.