Ultrasonography in Legg-Calvé-Perthes disease.

Ultrasonography was found to be a valuable investigation in the assessment and management of Legg-Calvé-Perthes disease (LCPD). It was used to assess 23 patients with LCPD in 25 affected hips and was compared with radiographs obtained at the same time. A chronological five-part staging of LCPD is proposed, expressing the degree of flattening and fragmentation as well as reconstitution of the femoral head as seen on ultrasound examination. Thickening of articular cartilage was documented, and associated findings of synovitis and lateral extrusion of the femoral head were evaluated. An intraarticular hip effusion was present in 74% of cases in stages I-II. Lateral extrusion increased from stage II onwards until the healing stage. The phase of reconstitution (stage IV) demonstrated both resorption of the necrotic bone and formation of new immature osteoid tissue. Lateral extrusion and the start of the healing phase can be shown earlier by ultrasonography than by radiography.