A Histological Evaluation of Rabbit Tendons Sutured Using the Bunnell Pattern

Development of ischemia in healing tendons was assessed in 18 rabbits. One superficial digital flexor tendon in each rabbit was incised and anastomosed using a Bunnell pattern. The repair site was enclosed in a porous, woven Dacron tube before skin closure. The limb was immobilized with a cast. Rabbits were euthanized 1, 4, and 8 weeks after surgery, and tendons were harvested and examined microscopically. Regions of the tendon included in the suture pattern were ischemic and acellular at 1 week, while adjacent areas still containing patent vessels remained viable. Within 4 weeks, a well vascularized neotendon with collagen bundles organized parallel to the long axis of the tendon developed along the periphery and between the opposed tendon ends. After 8 weeks, the ischemic regions of the tendon had not revascularized or become integrated with the neotendon. Adjacent collagen bundles not originally included in the Bunnell pattern were integrated with neotendon collagen fibers.