Bone scintigraphy and magnetic resonance imaging after transtrochanteric rotational osteotomy

Objective. To assess the ability of bone scintigraphy and magnetic resonanc e imaging (MRI) to predict the outcome of transtrochanteric rotational oste otomy (TRO) for osteonecrosis of the femoral head (ONFH). Design. This study was a prospective evaluation of imaging techniques. Patients and methods. MRI and bone scintigraphy were performed on 20 hips i n 18 patients at 3 months after TRO. The radiographic findings at 3 months after TRO, and the MRI and bone scintigraphic findings, were compared with the radiographic findings at final follow-up (mean 39 months). Results and conclusions. On MRI a low-intensity area or a low-intensity ban d in the new weight-bearing area extending over the acetabular edge on T1-w eighted images was related to the presence of collapse on the radiographs a t final follow-up. In hips with an area of absent activity in the new weigh t-bearing surface on bone scintigraphy, collapse was seen more frequently o n radiographs at final follow-up than in hips without this feature. Bone sc intigraphy was no more specific than radiography in predicting the outcome after TRO. We consider MRT to be superior to bone scintigraphy in predictin g the occurrence of collapse, which is one of the major short-term problems after TRO.