Histological Study Of Highly Agglutinative Staphylococcin In Enhancing Tendon-bone Healing After ACL Reconstruction In Rabbits

[Objective] To explore the effects of Highly Agglutinative Staphylococcin on tendon-bone healing after ACL (anterior cruciate ligament) reconstruction in rabbits.[Method] Animal model of ACL reconstruction in 24 mature New Zealand White rabbits were established using autologous digital long extensor tendon and randomly classified into 2 groups. The HAS (Highly Agglutinative Staphylococcin) group was separately given Highly Agglutinative Staphylococcin immediately after operation and two weeks after operation, which was injected into the tendon-bone interface. The control group was only injected with the same doses of physiological saline. All animals were sacrificed at 4,8,and 12 weeks after operation for histological examinations. The specimens were stained with hematoxylin-eosin, Masson trichrome and toluidin blue to investigate pathology changes of the tendon-bone healing tissue. The VEGF immunohistochemisty stain was used to observe the neo-vascularization of tendon-bone healing tissue. [Result] The histological examination revealed that at 4 weeks after operation, the tendon-bone interface of HAS group was filled with proliferated fibroblasts and chondroblasts, the collagen fibers was obviously increased, however, their arrangement was not regular enough. At 8 weeks after operation, the healing tissue at the bone-tendon interface had developed into dense connective tissue, the collagen fibers was formed abundantly, some Sharpey's-like fibers spanning parts of the tendon-bone interface, which indicated the formation of indirect insertion. At 12 weeks after operation, The transition zones of collagen fibers, fibrocartilage and bone (the structure alike a direct ligamentous insertion) occurred in the local region of tendon-bone interface. These histological observations showed that the tissue healing at tendon-bone interface of the HAS group was quicker than those of the control group. The proportion of neo-vessels at the tendon-bone interface of the HAS group was significantly higher than those of the control group at 4,8 and 12 weeks after operation (respectively p= 0.024, p=0.007). [Conclusion] Highly Agglutinative Staphylococcin can significantly improve the tendon-bone healing after ACL reconstruction in rabbits.