Biomechanical properties of four circumferential flexor tendon suture techniques.

Purpose: We introduce 2 interlocking circumferential flexor tendon suture techniques: the interlocking cross-stitch and the interlocking horizontal mattress repair and biomechanically tested them against 2 commonly used methods.
Methods: Thirty-two deep digital flexor tendons harvested from sheep hindlimbs were transected sharply. These were repaired without a core suture using 4 different circumferential repair techniques: group 1, simple running; group 2, cross-stitch; group 3, interlocking cross-stitch; group 4, interlocking horizontal mattress. All tendons were tested to failure at a distraction rate of 20 mm/min. Load to 2-mm gap formation, stiffness, load to failure, and method of failure all were assessed.
Results: The mean load to 2-mm gap formation was 22.8, 20.7, 20.0, and 26.1 N for groups 1, 2, 3, and 4, respectively. The mean stiffness was 7.6, 8.1, 8.7, and 10.1 N/mm, and the mean load to failure was 30.9, 42.1, 49, and 52.9 N for groups 1, 2, 3, and 4, respectively. There was no statistically significant difference between groups 2 and 3. Group 4, however, was statistically better than the others in all measured parameters (except group 3 in load to failure).
Conclusions: The interlocking horizontal mattress was the best performer overall, with statistically greater loads to failure, 2-mm gap formation, and stiffness. This technique could be considered for use in any patient likely to begin an early postoperative finger mobilization program.