The experimental study on the neochondrogenesis in free capsular autograft of rabbit

Objective: To determine whether the neochondrogenesis may be induced in free intraarticular autografts of the hip. Methods: In 24 young rabbits. A 5mm × 5mm synovial capsule of the hip was cut and folded back on itself so that its deep （synovial） layer was facing. The grafts were transplanted to both ipsilateral femoral head which was done by completely chondrectomized articular surfaces （4mm × 4mm） of femoral head except 8 left hips （control group）. The left hip of each rabbit was then placed in the continuous passive motion （CPM） apparatus for 3 weeks. The right hip regarded as subcontrol group was kept freely motion. Results: At the time of death （6 weeks and 12 weeks postoperatively）, some degree of neochondrogenesis was more evident in 87.5% （14/16） of the grafts in the group with CPM than in 29% （7/24） of the grafts in the group without CPM （χ²=13.099, P ＜0.001）, and was not available in the control group. Cartilage cells was presented in 12 week more than in 6 week. Conclusion: This investigation showed that the chondrogenic potential of free capsular grafts was better under the stimulating effect of CPM than free motion.