THE GROWTH-PLATE IN PERTHES-DISEASE - A P ROSPECTIVE-STUDY WITH MRI

Introduction In Perthes' disease, epiphyseal necrosis impairs the func tion of the growth plate and may result in growth disturbances of the femoral neck. The physeal changes during active disease were prospecti vely evaluated with magnetic resonance imaging (MRI). Materials and me thods MRI was performed and radiographs were obtained with six-month i ntervals from the time of diagnosis up to two years in nine hips (eigh t patients). Results Normal growth plate was seen in MRI as a stripe o f low signal intensity between areas of high signal intensity from the epiphysis and the metaphysis. Distortion, widening and partial disapp earance of the growth plate were noted in the hips classified into Cat terall groups 3 and 4. The physeal distortion was seen as anterior cur ling, and, in some hips, as a W-shaped abnormality projecting down int o the metaphysis. Delayed growth of the femoral neck, due to premature physeal closure, was noted in hips where the physeal deformation invo lved more than half of the growth plate. All pathological changes appe ared on the MRI scans three to fifteen months after the first symptoms . The extent of the MRI changes did not correlate directly with Catter all's plain film staging. Discussion The distortion and widening of th e growth plate seen in MRI probably reflect histological disarrangemen t of the physis due to an extensive epiphyseal necrosis. The physeal W -formation in MRI may represent a radiographic ''metaphyseal cyst''. D isappearance of the growth plate in MRI seems to indicate premature cl osure of the physis. Conclusion It seems possible to predict premature closure with MRI even within fifteen months after the onset of Perthe s' disease.