Ayabe Yusuke, Motomura Goro, Yamaguchi Ryosuke, Utsunomiya Takeshi, Sakamoto Kosei, Nakashima Yasuharu
Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-Ku, Fukuoka, 812-8582, Japan.
Skeletal Radiol. 2025 Jun;54(6):1275-1281. doi: 10.1007/s00256-024-04846-6. Epub 2024 Nov 29.
The presence of bone marrow edema on magnetic resonance imaging (MRI) in pre-collapse osteonecrosis of the femoral head is suggested to be a sign of occult subchondral fracture; however, to our knowledge, there are no histopathological studies verifying this. This study aimed to histopathologically verify the presence of subchondral fracture at the lateral necrotic boundary in symptomatic pre-collapse osteonecrosis of the femoral head with bone marrow edema on MRI.
Of 149 consecutive necrotic femoral heads resected during total hip arthroplasty at our hospital from January 2019 to June 2024, we included 13 femoral heads that did not show apparent collapse on preoperative radiographs and exhibited bone marrow edema on MRI. Continuous coronal-slice hematoxylin and eosin-stained specimens of each femoral head were examined for the presence of subchondral fracture. Bone microarchitectures around subchondral fractures were measured using micro-computed tomography (CT) images.
In all femoral heads, subchondral fractures were histopathologically confirmed at the lateral junction between the reparative and the necrotic zone. On micro-CT, bone volume fraction, trabecular thickness, and bone mineral density of the reparative zone adjacent to the subchondral fracture were all significantly higher than those of the necrotic zone adjacent to the subchondral fracture.
Subchondral fracture invariably existed when bone marrow edema was present on MRI during pre-collapse osteonecrosis of the femoral head. When bone marrow edema is observed on MRI, it should be known that subchondral fracture has already occurred, even if femoral head collapse is unclear on radiographs.
股骨头塌陷前期坏死的磁共振成像（MRI）上出现骨髓水肿被认为是隐匿性软骨下骨折的征象；然而，据我们所知，尚无组织病理学研究证实这一点。本研究旨在通过组织病理学方法验证MRI显示有骨髓水肿的有症状的股骨头塌陷前期坏死患者，在坏死灶外侧边界处是否存在软骨下骨折。
在2019年1月至2024年6月期间，我院行全髋关节置换术切除的149例连续坏死股骨头中，纳入13例术前X线片未显示明显塌陷且MRI显示有骨髓水肿的股骨头。对每个股骨头连续冠状切片苏木精-伊红染色标本进行软骨下骨折检查。使用微型计算机断层扫描（CT）图像测量软骨下骨折周围的骨微结构。
在所有股骨头中，均在修复区与坏死区的外侧交界处通过组织病理学证实存在软骨下骨折。在微型CT上，软骨下骨折相邻修复区的骨体积分数、小梁厚度和骨密度均显著高于软骨下骨折相邻坏死区。
在股骨头塌陷前期坏死时，若MRI上出现骨髓水肿，则必然存在软骨下骨折。当MRI观察到骨髓水肿时，即使X线片上股骨头塌陷不明显，也应知道软骨下骨折已经发生。
