ABSTRACT

Purpose: Trochlear dysplasia is one of the most frequent lower extremities deformities. Aim of this research was to investigate the changes in cartilage and subchondral bone of trochlea after patellar dislocation in growing rabbits.

Materials and Methods: Ninety-six knees from 48 one-month-old rabbits were divided into two groups (experimental, control). Lateral patellar dislocation was established in the experimental group and distal femurs were collected at 4, 8, 12 and 24-week time points, respectively. General examination and histological observations were conducted to research the anatomical structure of the trochlear cartilage and subchondral bone. Structural parameters of trochlear subchondral bone were measured by MicroCT. Subsequently, the expression of TRPV4, collagen II and MMP-13 in cartilage were detected by western blot and RT-PCR analysis, respectively.

Results: Subchondral bone loss was found in experimental group from 4 weeks after patellar dislocation, accompanied by increased TRAP-positive osteoclasts in subchondral bone. The trochlear dysplasia model was well established from 8 weeks after patellar dislocation. In addition, degeneration of cartilage was found from 8 weeks, accompanied by decreased expression of mechanically sensitive TRPV4 and collagen II, and increased expression of MMP-13.

Conclusions: This study proved that trochlear dysplasia can be caused by patellar dislocation in growing rabbits, accompanied by significant subchondral bone loss. What is more, this study also shows that degenerative cartilage changes occur in the patellar dislocation model and become aggravated with time, accompanied by decreased TRPV4 and collagen II, but increased MMP-13

摘要

目的：滑车发育不良是最常见的下肢畸形之一。本研究旨在探讨生长兔髌骨脱位后滑车软骨和软骨下骨的变化。

材料与方法：将48只1个月大的兔子96个膝关节分为两组（实验组、对照组）。实验组建立髌骨外侧脱位，分别在第4、8、12和24周时间点采集股骨远端。进行全身检查和组织学观察，研究滑车软骨和软骨下骨的解剖结构。通过MicroCT测量滑车软骨下骨的结构参数。随后，分别通过蛋白质印迹和RT-PCR分析检测软骨中TRPV4、胶原II和MMP-13的表达。

结果：实验组髌骨脱位4周后出现软骨下骨丢失，并伴有软骨下骨TRAP阳性破骨细胞增多。滑车发育不良模型从髌骨脱位后 8 周开始建立。此外，从8周开始发现软骨退化，伴有机械敏感性TRPV4和胶原蛋白II的表达减少，MMP-13的表达增加。

结论：本研究证明，生长兔的髌骨脱位可引起滑车发育不良，并伴有明显的软骨下骨丢失。更重要的是，本研究还表明，髌骨脱位模型中出现退行性软骨变化，并随着时间的推移而加重，并伴有TRPV4和胶原蛋白II减少，但MMP-13增加。