A partially biodegradable material device for repair and reconstruction of injured tendons

Abstract

We assessed the applicability of a partially biodegrad able synthetic material composed of polyglycolic acid (PGA) and dacron to repair or replace severely injured tendons. Adult rabbits underwent complete laceration and repair of one Achilles tendon. Group 1 (N = 8) had end to end tenorrhaphy with size 0 braided polyester suture, and Group 2 ( N = 16) tendons were similarly repaired with the bicomposite designed PGA-dacron device. Group 3 ( N = 16) received laceration and re moval of 1 cm of tissue, and the defect was bridged with the same PGA-dacron material. No postoperative immobilization was applied. Evaluation, consisting of biomechanical testing or histologic inspection, was done at 4 and 8 weeks after tenorrhaphy. All tendons healed, and at 8 weeks the mean maximum load at failure of the repaired tendons was 32.2 ± 3.4 kg_f, 40.3 ± 2.4 kg_f, and 31.8 ± 3.2kg _f for Groups 1, 2, and 3, respectively. Values between groups were not signifi cantly different, but all were significantly less ( P ≤ 0.05) than the strength of the unoperated control tendons (55.8 ± 7.2 kg_f). The most noteworthy finding was the lengthening of the repaired tendons, due to scar elon gation at the tenorrhaphy site, that occurred during healing as determined by a landmark placed a fixed distance proximal to the repair site. Group 1 tendons lengthened 22 mm, while Group 2 and 3 tendons in creased by 12.5 mm. Histologically, fibrous tissue in growth into the residual dacron scaffold occurred, but it was inconsistent and inadequate in quality and quan tity to be satisfactory as neotendon. The fibrous tissue did not mature or align in response to load. We con cluded that the PGA-dacron material had adequate strength and physical properties to use both for primary tenorrhaphy and to bridge the tendon defect. However, in our experience this material lacks any significant advantage over other materials available or known to be under evaluation to support neotendon formation when an actual soft tissue defect exists.