Shang Xiaoke, Chen Can, Zhou Jiefu, Yang Yang, Qu Jin
Department of Orthopedic Surgery, People's Hospital of Ningxia Hui Autonomous Region, Yinchuan, China.
Department of Orthopaedics, Xiangya Hospital, Central South University, Changsha, China.
BMC Musculoskelet Disord. 2025 Mar 19;26(1):277. doi: 10.1186/s12891-025-08508-z.
The purposes of the present study are to investigate the effects of reduced muscle loading by prolonged immobilization on the regeneration of fibrocartilaginous enthesis through endochondral ossification in rabbits.
Forty-eight rabbits underwent standard partial patellectomy were randomly divided into the control group and the prolonged immobilization (PIM) group. The immobilized cast was only maintained for the first 4 weeks in the control group, while for the first 12 weeks or until euthanization in the PIM group. The Patella-patella tendon complexes were harvested for Micro-CT and histology at week 6, 12 and 18.
There was significantly lower bone volume in the PIM group than the control group at week 12, but not at week 6 and 18. At week 6, new bone was formed at the osteotomy site of the residual patella through endochondral ossification. At week 12, the chondrocytes in the tendon to bone interface were ordered and arranged in longitudinal rows separated by collagen fibres in the control group. While there were no visible fibers running continuously from tendon into bone in the PIM group. At week 18, a nearly normal fibrocartilaginous enthesis were regenerated in the control group. A similar fibrocartilaginous enthesis were also formed at the tendon to bone interface in the PIM group, but the four zones were not as distinct as that in the control group.
Muscle loading and endochondral ossification are involved in the regeneration of a fibrocartilaginous enthesis during tendon to bone healing in this partial patellectomy model.
本研究旨在探讨长期固定导致肌肉负荷降低对兔纤维软骨性肌腱-骨结合部通过软骨内成骨再生的影响。
48只接受标准部分髌骨切除术的兔子被随机分为对照组和长期固定（PIM）组。对照组的固定石膏仅维持4周，而PIM组则维持12周或直至安乐死。在第6、12和18周采集髌-髌腱复合体进行Micro-CT和组织学检查。
在第12周时，PIM组的骨体积显著低于对照组，但在第6周和18周时并非如此。在第6周时，残余髌骨的截骨部位通过软骨内成骨形成了新骨。在第12周时，对照组肌腱-骨界面的软骨细胞有序排列，由胶原纤维分隔成纵向行。而在PIM组中，没有可见的纤维从肌腱连续延伸至骨内。在第18周时，对照组再生出近乎正常的纤维软骨性肌腱-骨结合部。PIM组在肌腱-骨界面也形成了类似的纤维软骨性肌腱-骨结合部，但四个区域不如对照组明显。
在这个部分髌骨切除模型中，肌肉负荷和软骨内成骨参与了肌腱-骨愈合过程中纤维软骨性肌腱-骨结合部的再生。
