目的： 探讨同步辐射X线显微断层成像（synchrotron radiation X-ray microtomography, SR-μCT）技术在兔骨关节炎（osteoarthritis,OA）模型软骨-软骨下骨复合体成像分析中的应用价值,探讨OA进展过程中的软骨和软骨下骨变化。方法： 将10只健康的6个月龄雄性新西兰大白兔随机分为实验组（改良Hulth法建立OA模型）和对照组（只打开关节腔不作任何处理）2组,每组5只,12周后处死,取膝关节胫骨内侧平台负重区软骨-软骨下骨复合体标本,经甲醛溶液固定、乙醇梯度脱水后行SR-μCT扫描,扫描后将原始投影图像行相位恢复、切片重构及三维重建后分析SR-μCT软骨细胞图像,观察比较软骨下骨形态结构和骨小梁微结构形态测量学指标。结果： SR-μCT重建图像可以清晰显示软骨细胞、软骨陷窝及其排列方式。对照组软骨细胞排列整齐,分布均匀;软骨表面光滑;实验组软骨细胞排列紊乱,可见软骨下裂隙,软骨表面毛糙、纤维化。对照组软骨下骨结构完整,骨小梁分布均匀;实验组软骨下骨小梁变薄,局部剥脱。骨小梁微结构形态测量学指标表明,实验组的骨体积分数（bone volume fraction, BVF）及骨小梁厚度（trabecular thickness,Tb.Th）[（26.64±1.64）%及（80.55±5.51） μm]均小于对照组[（39.00±2.28）%及（102.12±8.02） μm],差异有统计学意义（P<0.05）。结论： SR-μCT检查可在细胞层面上对软骨-软骨下骨复合体进行观察分析,而软骨退变及软骨下骨重塑在在OA进展中均有重要作用。

Objective: To explore the value of synchrotron radiation X-ray microtomography (SR-μCT) in the imaging analysis of bone-cartilage unit in rabbit osteoarthritis(OA) model, and to determine the changes of cartilage and subchondral bone in the progress of OA. Methods: A total of 10 healthy male New Zeal and white rabbits aging 6-month were randomly divided into study and control group, 5 animals in each group. To establish OA model, the rabbit in the study group got surgery on the knees using modified Hulth method, while rabbits in the control group were only treated by opening the joint cavity. All the animals were sacrificed 12 weeks later. The samples of bone-cartilage unit collected in the load-bearing area of medial tibial plateau were fixed in formaldehyde solution and dehydrated by an ethanol gradient,and scanned with SR-μCT. All original images were processed by phase retrieval, slicere construction and three-dimensional reconstruction. The image of chondrocytes, the morphology and quantitative parameters of subchondral bone trabe-cula were analyzed. Results: The reconstructed images of SR-μCT could clearly display the chondrocytes, cartilage lacunae and their arrangement. The chondrocytes in the control group were arranged orderly and evenly, and the surface of cartilage was smooth, while chondrocytes in the study group were arranged disorderly and the deep fissures and the surface fibrillations appeared in the cartilage matrix. The subchondral bone trabecular in the control group was also distributedcompletely and evenly, and subchondral bone trabecular in the study group became thinner and locally exfoliated. The quantitative analysis of subchondral bone morphology showed that the bone volume fraction(BVF)(26.64%±1.64% vs 39.00%±2.28%) and trabecular thickness (Tb.Th)[(80.55±5.51) μm vs(102.12±8.02) μm] in the study group were lower than those in the control group(P<0.05). Conclusions: SR-μCT can be used for imaging analysis of bone-cartilage unitat cellular level. Both cartilage degeneration and subchondral bone remodeling play an important role in the development of OA.