A new model for partial immobilization of rat hind limb after Achilles tendon excision/reinterposition

Abstract

There have been several attempts to repair the Achilles tendon by surgery or replacement with graft materials. Because tissue repair is a complex process, tendon healing occurs slowly. In rats, immobilization of the limb is essential during recovery. There are immobilization methods such as plaster or fiber casting. According to prolonged recovery, most of the procedures cause skin ulceration, decrease in weight, restrictions in checking the surgery area, and slipping out of the cast. Our aim was to apply a suture around the defect for immobilization. Tendons of 30 male Wistar rats (250 +/- 50 g and aged 8 +/- 2 weeks) were dissected and the cut ends were immediately sutured proximally-distally with an 8-0 nonabsorbable suture. For partial immobilization a needle with a 4-0 suture was passed 3 mm proximally and 3 mm distally between the gastrocnemius and calcaneus. A knot was applied close to the calcaneus. The skin was closed with a continuous, Ford interlocking 6-0 suture pattern. The animals were sacrificed after 2 and 4 weeks. No difference was observed in means of muscle atrophy when compared to contralateral intact muscle. No ulcer, sore, or swelling was observed. Tendons were intact and showed superior histological characteristics. Recent techniques seem to be effective in applying strength to protect the defect area from muscle tensile stress of the gastrocnemius during the recovery period.