Morphological and Biochemical Changes of Transitional Zone after Achilles Tendon-bone Autogenous and Allogeneic Graftin Rabbitis Achilles Tendon-bone Autogeous and Allogeneic Graft in Rabbits / 대한정형외과연구학회지

ABSTRACT

Allografts or autografts of bone-tendon unit have been used for ligament injuries or deficiencies after limb salvage operation for malignant bone tumors around joints. While the remodeling process of the ligament or tendon of the allograftor autograft and the microscopic and biomechanical changes of tendon-bone graft interface have been widely investigated, little is known about the ultrastructural and biochemical changes of the transitionall zone in tendon-bone junction. This study was performed to analyzed the ultrastructural and biochemical changes of the transitional zone after tendon-bone auto-and allo-grafting. A total of twenty four rabbits were divided into two group. In 12 animals(allograft group), two Achilles ten-don-bone unit per each animal were taken and transplanted to another rabbit after preservation below -70degrees C for 2 weeks. In the other 12 animals(autograft group), the Achilles tendon-bone unit was harvested from one side and transplanted to the other side of the rabbit. After operation, their legs were immobilized with short leg cast for 4 weeks, and then mobilized freely. Four animals in each group were sacrificed at four, eight and sixteen-weeks after the transplantation, and their grafted Achilles tendon-bone interfaces were used for analysis of the ultrasturctural and biochemical changes. The following results were obtained. 1. Histologically new cartilage cells were observed at postoperative 16 weeks with local presence of faint tidemark in the autograft group but not in the allograft group. Complete remodeling of the transitional zone had not observed histologically in both groups. 2. Ultrasturctural analysis revealed no definite differences between both groups. However, the slightly rapid appearance of parallelism and cross-striation of microfibrils in the autograft group and time-related restoration of fibers and fibroblasts were observed. 3. From biochemical analysis, type I collagen concentratin was increased, and an early rapid increase of type III collagen and glycosaminoglycan were also observed. In conclusion, these data suggested that type III collagen and glycosaminoglycan are important in stabilization of grafted tendon-bone unit, especially in the transitional zone. The histological and biochemical changes in allograft group were relatively similar to that of autograft group although the allograft group showed the delayed pattern of remodeling. Therefore, the tendon- allograft could be used as a good substitute for the autograft for tendon or ligament reconstruction when no suitable autograft is available.