Adhesion formation after flexor tendon repair: a histologic and biomechanical comparison of 2- and 4-strand repairs in a chicken model

Abstract

Purpose Both increased handling and increased bulk at the repair site have been hypothesized as affecting adhesion formation and gliding after tendon repair. Tendons repaired with 2- and 4-strand techniques were compared using both biomechanical and histopathologic measurements to determine the influence of increasing strand number on adhesion formation and gliding. Methods The flexor digitorum profundus tendon of the right middle toe of 80 broiler chickens was cut and then repaired with either a single (2-strand) or double (4-strand) modified Kessler core suture, followed by a running epitendinous suture. The limb was immobilized after surgery. Birds were killed at either 3 days or 4 weeks after tendon repair and adhesion formation measured using either biomechanical testing or quantitative and qualitative histology. For biomechanical testing, the tendon was pulled free of the sheath and a force versus displacement curve was generated. Comparisons of peak force and work to peak were made. Histologic specimens were examined by a pathologist blinded to the treatment group who scored the length and density of adhesions and made qualitative observations. Results Both biomechanical and histologic data showed expected differences in adhesion formation for early (3 days) and late (4 weeks) healing but no significant differences between 2- and 4-strand repairs. Biomechanical testing of 4-week specimens showed a nonsignificant tendency toward greater work required to break adhesions in 4-strand repairs. Conclusions Adhesion formation and gliding resistance of tendons after 2- or 4-strand modified Kessler core suture were not significantly different, which suggests that simply increasing the number of strands crossing a repair does not necessarily result in more adhesions or resistance in this model.