Zhang Weijie, Lian Qin, Li Dichen, Wang Kunzheng, Jin Zhongmin, Bian Weiguo, Liu Yaxiong, He Jiankang, Wang Ling
Zhongguo Xiu Fu Chong Jian Wai Ke Za Zhi. 2014 Mar;28(3):318-24.
To investigate whether subchondral bone microstructural parameters are related to cartilage repair during large osteochondral defect repairing based on three-dimensional (3-D) printing technique.
Biomimetic biphasic osteochondral composite scaffolds were fabricated by using 3-D printing technique. The right trochlea critical sized defects (4.8 mm in diameter, 7.5 mm in depth) were created in 40 New Zealand white rabbits (aged 6 months, weighing 2.5-3.5 kg). Biomimetic biphasic osteochondral composite scaffolds were implanted into the defects in the experimental group (n = 35), and no composite scaffolds implantation served as control group (n = 5); the left side had no defect as sham-operation group. Animals of experimental and sham-operation groups were euthanized at 1, 2, 4, 8, 16, 24, and 52 weeks after operation, while animals of control group were sampled at 24 weeks. Subchondral bone microstructural parameters and cartilage repair were quantitatively analyzed using Micro-CT and Wayne scoring system. Correlation analysis and regression analysis were applied to reveal the relationship between subchondral bone parameters and cartilage repair. The subchondral bone parameters included bone volume fraction (BV/TV), bone surface area fraction (BSA/BV), trabecular thickness (Tb.Th), trabecular number (Tb.N), and trabecular spacing (Tb.Sp).
In the experimental group, articular cartilage repair was significantly improved at 52 weeks postoperatively, which was dominated by hyaline cartilage tissue, and tidal line formed. Wayne scores at 24 and 52 weeks were significantly higher than that at 16 weeks in the experimental group (P < 0.05), but no significant difference was found between at 24 and 52 weeks (P > 0.05); the scores of experimental group were significantly lower than those of sham-operation group at all time points (P < 0.05). In the experimental group, new subchondral bone migrated from the surrounding defect to the centre, and subchondral bony plate formed at 24 and 52 weeks. The microstructural parameters of repaired subchondral bone followed a "twin peaks" like discipline to which BV/TV, BSA/BV, and Tb.N increased at 2 and 16 weeks, and then they returned to normal level. The Tb.Sp showed reversed discipline compared to the former 3 parameters, no significant change was found for Tb.Th during the repair process. Correlation analysis showed that BV/TV, BSA/BV, Tb.Th, Tb.N, and Tb.Sp were all related with gross appearance score and histology score of repaired cartilage.
Subchondral bone parameters are related with cartilage repair in critical size osteochondral repair in vivo. Microstructural parameters of repaired subchondral bone follow a "twin peaks" like discipline (osteoplasia-remodeling-osteoplasia-remodeling) to achieve reconstruction, 2nd week and 16th week are critical time points for subchondral bone functional restoration.
基于三维（3-D）打印技术，研究大的骨软骨缺损修复过程中软骨下骨微观结构参数与软骨修复是否相关。
采用3-D打印技术制备仿生双相骨软骨复合支架。在40只6月龄、体重2.5 - 3.5 kg的新西兰白兔上制作右侧滑车关键尺寸缺损（直径4.8 mm，深度7.5 mm）。实验组（n = 35）将仿生双相骨软骨复合支架植入缺损处，对照组（n = 5）不植入复合支架；左侧无缺损作为假手术组。实验组和假手术组动物在术后1、2、4、8、16、24和52周处死，对照组动物在24周取样。使用Micro-CT和韦恩评分系统对软骨下骨微观结构参数和软骨修复进行定量分析。应用相关性分析和回归分析揭示软骨下骨参数与软骨修复之间的关系。软骨下骨参数包括骨体积分数（BV/TV）、骨表面积分数（BSA/BV）、骨小梁厚度（Tb.Th）、骨小梁数量（Tb.N）和骨小梁间距（Tb.Sp）。
实验组术后52周关节软骨修复明显改善，以透明软骨组织为主，形成潮线。实验组24周和52周的韦恩评分显著高于16周（P < 0.05），但24周和52周之间无显著差异（P > 0.05）；实验组各时间点评分均显著低于假手术组（P < 0.05）。实验组中，新的软骨下骨从周围缺损向中心迁移，24周和52周形成软骨下骨板。修复后的软骨下骨微观结构参数呈现“双峰”规律，BV/TV、BSA/BV和Tb.N在2周和16周增加，然后恢复到正常水平。Tb.Sp与前3个参数呈现相反规律，修复过程中Tb.Th无显著变化。相关性分析表明，BV/TV、BSA/BV、Tb.Th、Tb.N和Tb.Sp均与修复软骨的大体外观评分和组织学评分相关。
体内大尺寸骨软骨修复中软骨下骨参数与软骨修复相关。修复后的软骨下骨微观结构参数遵循“双峰”规律（成骨 - 重塑 - 成骨 - 重塑）实现重建，第2周和第16周是软骨下骨功能恢复的关键时间点。
