Correlation of MRI and histomorphological findings in bone marrow oedema syndrome of the hip

Bone marrow oedema syndrome (BMOS) of the hip includes severe hip joint pain, focal loss of radiodensity in radiographs, increased uptake in bone scintigrams and the pattern of bone marrow oedema in the femoral heads in MRI scans. In 15 patients (16 hip joints) we found the clinical and radiological signs of BMOS. On T1-weighted MRI images areas of low signal intensity could be observed in the head, neck and the intertrochanteric region of the femur in various extensions. These areas showed a significant increase in signal intensity on the T2-weighted images. Because pain was resistant to conservative therapy all these patients were treated by core decompression of the femoral head in a prospective study. Bone cores were evaluated histologically using undecalcified sections and quantitative microradiography. The existence of intramedullary oedema in exactly the regions exhibiting the MRI pattern of bone marrow oedema was verified histologically; however, bone and marrow changes similar to those of early avascular necrosis (AVN) were also visible. These findings support our assumption that BMOS might be a transitory initial phase of AVN. Therefore core decompression treatment for patients suffering pain from BMOS is recommended after excluding other diseases.