Collagen ribbon augmentation of Achilles tendon tears: a biomechanical evaluation.

Early motion of a repaired Achilles tendon has been accepted to improve both clinical and biomechanical outcomes. It has been postulated that augmenting a primary Achilles tendon repair with a collagen ribbon will improve the repair construct's initial strength, thereby facilitating early motion. The purpose of the present study was to compare the failure load of Achilles tendon defects repaired with suture, with or without augmentation with a collagen ribbon. Ten matched pairs of cadaveric feet and tibiae underwent simulated Achilles tendon tear in the watershed area and were then repaired with 4-strand Krackow sutures only or were sutured and augmented with a box weave collagen ribbon xenograft. The specimens were prepared for testing by keeping the insertion of the Achilles to the calcaneus intact and dissecting the gastrocnemius at its origin, leaving the repair undisturbed. The mean load at failure for the augmented (suture plus collagen ribbon) specimens was 392.4 ± 74.9 N. In contrast, the mean load at failure for the suture-only (control) construct was 98.0 ± 17.6 N (p < .001). The augmented specimens demonstrated a greater mean strength of 4.1 ± 0.9 N (range 3.2 to 5.6). After cyclic loading, the mean gap across the Achilles repair was significantly smaller in the augmented group than in the control group (p = .006). We have concluded that box weave collagen ribbon augmentation of the primary suture Achilles tendon repairs can provide enhanced gap resistance and strength under cyclic loading and ramped tensile testing.