| Purpose: the objective of this study was to investigate the biological healing and restoration of mechanical function in the augmented reconstruction with autologous semitendinosus tendon(ST) in rabbits , so as to provide some evidences of histological and biomechanical for the clinical treatment of the isolated partial tears of ACL.Methods: thirty-six mature new Zealand rabbits were included in this experiment, 50% CCL of both two knee joints were excised to create control model of isolated partial tears of the CCL in thirty-two rabbits, the rest were selected as normal specimens in histological examination and biomechanical test. In experimental group, augmented reconstruction was carried out with preservation of remnant bundle; in control group, conservative management was carried out without ACL reconstruction. Every eight rabbits were euthanized at 4,12,16 and 24 weeks postoperationally with an overdose of sodium phenobarbital. Descriptive analysis of histological changes and quantitative analysis of biomechanical characteristics were carried out.Results: 1.Gross anatomic observation: At 4 weeks postoperatively, connective tissue filled between the tendon graft and remnant bundle in experimental group, two bundles were completely fused at 12 weeks postoperatively. While in control group, remnant bundle did not have any obviously elongation and disfiguration. 2. Histological property: At 4,12,16 and 24 weeks postoperatively, Collagen fibers and fibrocytes of experimental group arranged more regular than that of control group, obvious degeneration can be detected in remnant bundle of control group. Grafts of experimental group had experienced ligamentization process after reconstruction, and differences had become less distinct between experimental group and intact CCL at 24 weeks.3. Biomechanical testing: The maximum load and stiffness of experimental group were siganificantly greater than control group at each time of 4,12,16 and 24 weeks postoperatively(p<0.05). At 4,12weeks the maximum stress and elastic modulus of experimental group were siganificantly smaller than control group(p<0.05), but there were no statistical difference at 24 weeks(p>0.05). Biomechanical values of control group were gradually decreased postoperatively, of which elastic modulus drcreased siganificantly from 4 weeks to 24 weeks (p<0.05). The biomechanical values of both experimental group and control group were all smaller than intact CCL group at 24 weeks postoperatively.Conclusions: 1. CCL's histological characteristics and biomechanic property in experimental group are superior to control group. 2. The remnant bundle will experience degeneration after partial tears of CCL, graft in augmented reconstruction group can postphone degeneration of remnant bundle. 3. Both groups haven't attained normal CCL's histological characteristics and biomechanic property even after 24 weeks. |
