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

Abstract

To evaluate the combined use of several ultrasonographic (US) criteria in the detection of Perthes disease. 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. 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%. The combination of several US criteria increases the diagnostic value of US of the painful hip in patients with Perthes disease.