SYNOVITIS IN LEGG-CALVE-PERTHES DISEASE - EVALUATION WITH MR-IMAGING IN 84 HIPS

Purpose. To evaluate, by means of MR imaging, the degree and persisten ce of synovitis in the hip joint in Legg-Calve-Perthes disease and to correlate the degree of synovitis with the degree of epiphyseal necros is. Material and Methods: A total of 170 MR images in 72 patients (84 hips) were examined. The T2-weighted MR images were taken in the coron al plane in order to evaluate the degree of synovitis in the hip joint . Results: MR revealed synovitis in all cases in the early phase of th e disease. In Catterall group II, synovitis was discreet to moderate f or up to 6 months after diagnosis. Hips with more severe necrosis, Cat terall groups III and IV, had moderate or intense degrees of synovitis . There was a correlation between the degree of synovitis and the late ral pillar classification according to HERRING et al. Also, there was a good correlation between the extent of signal changes in the epiphys is on MR imaging and the degree of synovitis. There was no difference when signal changes were evaluated on T1- or T2-weighted images. Signs of synovitis could be seen for up to 30 months after diagnosis in Cat terall group I hips, and in Catterall groups II and III for up to 36 m onths, and in 2 cases even loner. Some Catterall group IV hips had dis creet or mild synovitis for 60 months or more, after diagnosis. Conclu sion: The degree of synovitis on MR imaging correlates to the extent o f epiphyseal necrosis seen on radiographs or MR imaging as well as to the lateral pillar classification, i.e. loa poor clinical outcome. In Catterall group IV hips, synovitis can even persist for up to 60 month s after diagnosis.