Diagnosis of avascular necrosis of the hip in asymptomatic HIV-infected patients: Clinical correlation of physical examination with magnetic resonance imaging

Abstract

Objective:

To determine if physical examination can identify avascular necrosis of the hip (AVN) in asymptomatic HIV-infected patients.

Design:

Prospective, blinded population study

Results:

Ten of the 176 patients were positive for AVN by MRI. Four subjects had unilateral disease and six had bilateral disease. Five hips (1.4%) in four patients were indeterminate. We evaluated physical examination maneuvers both singly and in combination. Tests done singly generally provided a higher degree of specificity (67–92%) but sensitivities were lower (0–50%) with all p-values $\ge 0.08$ . Positive predictive values based on physical exam, were $\mathrm{<}17\mathrm{\%}$ and negative predictive values were $\mathrm{>}90\mathrm{\%}$ for any single test. Combining all tests gave a high sensitivity (88%) and negative predictive value (98%), but low specificity (34%) and positive predictive value (6%) with p = 0.10. Only two of 16 hips with positive MRI findings showed no abnormalities when all tests were combined

Conclusions:

This study establishes the limited usefulness of a detailed physical examination of the hip early in the course of AVN. Patients who test negative on physical exam are unlikely to have AVN positive by MRI. Positive findings on physical examination of the hip may help identify patients who need further evaluation by MRI based on overall clinical suspicion.