Suture methods for flexor tendon repair: A biomechanical analysis during the first six weeks following repair

Abstract

This review describes the evolution of recently developed multi-strand, multi-grasp flexor tendon suture techniques. Analyses of digital angular joint rotation, tendon excursion, and ultimate tensile load at the time of repair and at three and six weeks following repair allowed comparison of a variety of innovative grasping and non-grasping multi-strand techniques. The first series of experiments describes an analysis of the Tajima, Tsuge, Savage, Kessler, double loop locking suture, and recently developed eight-strand suture techniques at the time of repair. The Tajima, Savage, and eight-strand repair methods were found to have statistically significant improved gliding function compared to those methods that featured external knots (Kessler and Tsuge) and methods that tended to bunch at the repair site (double loop locking suture). With regard to ultimate tensile load, the eight-strand repair was found to have the greatest strength (69N) of all tested methods (p < 0.05). The second series of experiments examined the Tajima, Kessler, Savage, and eight-strand suture methods at three and six weeks following tendon repair. A high percentage of failure within the Kessler repairs precluded their inclusion for final comparative analysis. The results for the remaining three techniques were normalized (experimental/control) to allow inter-group comparison. For intrasynovial tendon repair gliding function, all prepared specimens were found to have significantly less tendon excursion, proximal interphalangeal joint rotation, and distal interphalangeal joint rotation than their respective controls. However, no statistical differences were noted in gliding function between the Tajima, Savage, and eight-strand repair at three and six weeks (p < 0.05). Ultimate tensile testing ascertained that the eight strand method demonstrated significantly greater strength at three (52.6N) and six (70.9N) weeks than both the Tajima and Savage techniques (p < 0.05), while the Savage repair had significantly greater strength than the Tajima repair (p < 0.05). On the basis of these findings, we suggest that early controlled active motion protocols be devised using the multi-strand multi-grasp techniques, as exemplified by the eight strand tendon repair method, in an effort to achieve consistently improved results for intrasynovial flexor tendon repairs.