Effects of periosteum wrapped around tendon in a bone tunnel: a biomechanical and histological study in rabbits

The present study demonstrated the effects of periosteal autograft on tendo n-to-bone healing in the rabbits. In 20 Japanese white rabbits, proximal en d of the long digital extensor tendon that was wrapped around by a perioste um was transplanted into a drill hole in the proximal tibial metaphysis. A fresh periosteum was used in the left tibia and a frozen periosteum was use d in the right tibia. Six specimens were harvested at each 2, 4, and 6 week s postoperatively. Radiological features showed progressive remodeling of t rabecular bone surrounding the implanted tendon. This remodeling in fresh p eriosteal graft was earlier than that in frozen graft. Generally, the pull- out strength of the transplanted tendons with a fresh or frozen periosteum increased progressively according to the length of the healing periods. The strength was significantly greater in a fresh periosteal graft than that i n a frozen graft at 4 weeks postoperatively. In hisotological analysis, a 4 -week specimen with the fresh periosteal graft showed fibrocartilage format ion in the bone tendon interface, whereas the specimens with the frozen gra ft demonstrated simple approximation of oriented fibrous tissue. In conclus ion, the fresh periosteal autograft produced the premature form of fibrocar tilagenous attachment in a bone tunnel and provided good mechanical strengt h.