膝骨关节炎患者软骨和软骨下骨微结构改变

Changes of microstructure in cartilage and subchondral bone of patients with knee osteoarthritis

目的观察膝骨关节炎(OA)患者胫骨平台硬化区与非硬化区软骨和软骨下骨微结构的改变,探讨膝OA的不同部位、不同病变阶段的病变特点.方法收集OA患者行全膝关节置换术后遗弃的胫骨平台组织,大体观察后,区分硬化与非硬化区,通过扫描和透射电镜观察软骨和软骨下骨组织和细胞微结构改变,通过Micro-CT检测并比较软骨下骨骨矿化密度(BMD)、骨体积分数(BV/TV)、骨小梁数目(Tb.N)、骨小梁厚度(Tb.Th)骨小梁间隔(Tb.Sp)及结构模型指数(SMI),计量资料以均值±标准差(Mean±SD)表示,组间采用独立样本t检验.结果与非硬化区比较,扫描电镜观察显示硬化区软骨变薄,胶原纤维排列紊乱可见深达软骨下骨的裂隙;软骨下骨骨板增厚,骨小梁增粗.透射电镜观察显示硬化区软骨细胞的细胞核皱缩不规则,粗面内质网扩张,高尔基体不发达,线粒体水肿;骨细胞骨基质胶原纤维排列稀疏;破骨细胞次级溶酶体较多,亮区微丝减少;成骨细胞胞体皱缩,表面无细小突起;软骨下骨可见多个微血管形成.Micro-CT检测显示,与非硬化区比较,硬化区BMD(98.040±20.600,t=7.931,P< 0.01)、BV/TV(40.060±7.110,t=11.959,P <0.01)、Tb.N(1.540±0.181,t=6.212,P <0.01)、Tb.Th(0.250±0.039,t=8.070,P<0.01)增高,Tb.Sp (0.43±0.047,t=8.566,P<0.01)及SMI(0.83±0.124,t=10.803,P<0.01)降低,与非硬化区比较差异有统计学意义(P均<0.01).结论 OA硬化区软骨和软骨下骨微结构都不同于非硬化区,硬化区软骨和软骨下骨微结构的病变值得进一步研究.

Objective To investigate microstructure changes of cartilage and subchondral bone in the nonsclerotic and sclerotic zones of the tibial plateau in patients with knee osteoarthritis (OA), and explore the pathological features of different parts and stages of knee OA. MethodsTibial plateau tissues abandoned after total knee arthroplasty were collected in OA patients. After gross observation, the cartilage and subchondral bone were divided into nonsclerotic and sclerotic zones. The pathologic changes of tissue and cell microstructure characteristics were observed by scanning and transmission electron microscopies, and the microstructure of subchondral bone was evaluated by Micro-CT scanning system. ResultsAs compared with the nonscleroic zone, scanning electron microscopy showed that the cartilage morphology of the scleroic zone was chaotic and thinner, and surface collagen fibers were disarranged. The cracks to the subchondral bone were observed. The subchondral bone plate and trabecular bone were thickened, and gap narrowed. The transmission electron microscopy showed that the nucleus of the chondrocytes in the scleroic zone was irregular, and the rough endoplasmic reticulum was dilated, the Golgi apparatus was underdeveloped, and mitochondria displayed edema. Bone matrix collagen arranged sparsely. Secondary lysosomes increased and bright microfilament reduced in osteoclasts. The osteoblast envelope was wrinkled with no small protuberances on the surface. The microvascular formation was seen in the scleroic zones. The micro-computed tomography showed bone mineral density (BMD, 98.040±20.600), BV/TV (40.060±7.110), Tb.N (1.540±0.181) and Tb.Th (0.250±0.039) were increased, and Tb.Sp (0.43±0.047) and SMI (0.83±0.124) decreased in the scleroic zone as compared with the non-sclerotic zone (t=7.931, 11.959, 6.212, 8.070, 8.566, 10.803, P<0.05). ConclusionThe microstructure of cartilage and subchondral bone in OA sclerotic area is different from that in nonsclerotic area. The microstructure of cartilage and subchondral bone in the sclerotic area should be further studied.