Tensile strength of the end-weave flexor tendon repair. An in vitro biomechanical study

A study was designed to investigate the tensile strength of the end-weave method of tendon repair. Flexor tendons were removed from 13 fresh-frozen human cadavers, transected and repaired with the end-weave technique varying from one to five weaves, with two suture techniques, the commonly used horizontal mattress suture and a new method we have termed the cross stitch. The repairs were then tested in tension to failure on a Materials Test System (MTS) biomechanical testing device. Comparisons were also made to tensile strengths of intact whole tendons, tendon-bone insertions, and distal reinsertion techniques. Tensile strength increased linearly with the number of weaves for both suture methods. The cross stitch was found to have significantly greater strength per weave compared to the horizontal mattress suture (P < 0.05). Three out of five trials of five weaves done with the cross stitch actually failed at the tendon itself first, rather than through the repair, which was the failure mode for all other trials. The results from this in vitro model suggest that active rehabilitative exercises might safely be performed in the immediate post-operative period after procedures that involve tendon weaving.