ULTRASONOGRAPHY OF THE PATELLOFEMORAL JOINT IN DIASTROPHIC DYSPLASIA

Plain radiographs do not provide adequate information in diastrophic d ysplasia (DD) because of abnormal ossification and severe deformation of the knee joint. Radiographically, the lateral femoral condyle is hy poplastic, and the position of patella is difficult to define. In clin ical examination, the patella is inferior and lateral. In this study, the anatomy of the patellofemoral joint in DD is described using ultra sound. Both knees of 13 patients with DD were examined. The alignment of patella, the angle of femoral sulcus, and the size of both femoral condyles were measured. Student's paired t test with two-tailed signif icance probability was applied for differences in mean values, and the ir 95% confidence limits were computed. The femoral sulcus angle avera ged 129 degrees and was deeper than that (142 degrees) in normal knees . The lateral femoral condyle was smaller than the medial condyle. The patella was aligned lateral to the bottom of femoral sulcus. In 10 de grees knee flexion, the patella remained laterally in the sulcus with no true patellar dislocation. Vertical position of the patella average d 2.9 mm distal to the femorotibial joint. The study showed that, in p atients with DD, the anatomic complex of the femoral condyles and pate lla deviates laterally, and the patellofemoral joint is deformed with a hypoplastic lateral condyle, a deep femoral groove, and a distally a ligned patella.