IS TRANSIENT OSTEOPOROSIS OF THE HIP (TOH) INVOLVED IN THE ENTIRE FEMORAL HEAD?
Hiranuma Y, Atsumi T, Kajiwana T, Asakura Y
Department of Orthopaedic Surgery, Fujigaoka Hospital, Showa University School of Medicine, Yokohama Japan

It is commonly recognized that T1-weighted image reveals the diffuse low intensity and T2-weighted image shows matching high intensity on MRI of TOH. Although the demarcation of these findings is unclear different from that of the osteonecrosis, the extent has the difference among each case. So we investigated the location of the bone marrow edema pattern (BME pattern). MRI in the mid-coronal slice of the femoral head was performed in 21 hips with TOH. BME pattern was classified following three types: showing at entire involvement of the femoral head, at extensive area without medial small normal intensity part, and exclusively at the mid-portion. There was no case with entire involved lesion of the femoral head. Sixteen cases disclosed the BME pattern at the extensive lesions except the thin medial normal part. The lesions at mid-portion of the femoral head were found in the remaining five cases.