Comparison of carbon fibre and nylon suture for repair of transected flexor tendons in the horse

Summary Carbon fibre-polylactic acid composites and monofilament non-absorbable suture material were compared for the repair of surgically transected superficial digital flexor tendons in 10 horses. All surgical wounds healed by first intention. The repaired tendons were enlarged, the carbon implanted tendons being larger than those sutured. The horses were killed at six, eight, 12, 20 or 24 weeks. Greater fibrous thickening occurred in tendons repaired with carbon fibre, especially at 12 weeks postoperatively. Carbon fibre incited a greater histological response with macrophages, lymphocytes, plasma cells, eosinophils and fibroblasts. The fibrous tissue in the repair sites appeared to mature and the collagen to align at a similar rate irrespective of the method of repair. Only that tissue within and immediately surrounding the carbon bundles was immature at six months. There was minimal tendency for carbon filaments to separate and those that did were often surrounded by epithelioid macrophages forming a granuloma. Massive eosinophil concentrations were present between each granuloma. With each sequential test period the sutured tendons became increasingly stronger than the carbon implanted tendons. This may have been because of the immature core of tissue associated with the carbon bundles. No carbon particles were detected in draining lymph nodes.