Muscle transplant in the rabbit's Achilles tendon

Achilles tendinopathy (AT) is a degenerative disorder resulting from functional overload, especially during running and jumping, with some inflammatory features at the insertions, bursae, and paratenon. The Achilles tendon is poorly vascularized, especially in the middle third, and the consequent slow metabolic rate allows it to work at very low oxygen tensions but prevents on the other hand a rapid healing. PURPOSE: To create an animal model to study a novel surgical technique employed in AT: transplanting some fibers of the soleus muscle into the tendon in order to improve its vascularization and healing and to study the histological appearance of the soleus graft incorporated in the tendon. METHODS: We operated on 10 white New Zealand rabbits (eight rabbits underwent the procedure, two rabbits the sham operation with incision of the tendon without graft). Two animals were euthanized at 1 wk, 1, 2, and 3 months. RESULTS: Histology showed that after 3 months the muscle fibers were still viable within the tendons, interspersed within connective tissue fibers. Tendon and muscle tissues were intimately fused. CONCLUSIONS: The persistence of the soleus muscle pedicle graft within the Achilles tendon tissue is an index of sound blood supply. This surgical model is suitable for application in further studies on tendon healing.