US of the painful hip in childhood: diagnostic value of cartilage thickening and muscle atrophy in the detection of Perthes disease.

Abstract

PURPOSE: To evaluate the combined use of several ultrasonographic (US) criteria in the detection of Perthes disease. MATERIALS AND METHODS: In a prospective study, 144 consecutive children with a painful hip underwent US. The thicknesses of the (a) anterior recess of the joint capsule, (b) cartilage of the femoral head, and (c) quadriceps muscle were assessed. Sixty-eight children with no symptoms, the control group, were also examined. RESULTS: The final diagnosis was transient synovitis (n = 58), Perthes disease (n = 21), slipped capital femoral epiphysis (SCFE; n = 5), or miscellaneous (n = 6). Fifty-four patients had no US or radiographic abnormalities, and symptoms disappeared during follow-up. The anterior recess in patients with transient synovitis was significantly wider than that in the other patients and control subjects (P < .001). Patients with Perthes disease showed significant cartilage thickening in the symptomatic hip compared with the other patients and control subjects (P < .001). Patients with Perthes disease and patients with SCFE showed significant atrophy of the ipsilateral quadriceps muscle compared with all other groups (P < .001). The combined use of these US criteria for the diagnosis of Perthes disease resulted in a positive predictive value of 95%, a negative predictive value of 95%, a sensitivity of 71%, and a specificity of 99%. CONCLUSION: The combination of several US criteria increases the diagnostic value of US of the painful hip in patients with Perthes disease.