The Effect of Increased Peripheral Suture Purchase on the Strength of Flexor Tendon Repairs

Purpose: Previous studies have hypothesized unequal load sharing between peripheral and core sutures in flexor tendon repairs. Most commonly peripheral sutures are placed very near the repair site and characteristically fail before the core strands. We hypothesized that placement of the peripheral sutures farther from the repair site would better optimize load sharing and resist suture pullout, yielding a stronger overall repair.

Methods: To test the hypothesis we developed a mathematical model of the load sharing between core and peripheral sutures. By using this model we predicted that placement of peripheral sutures 2 mm from the repair site would optimize the balance of load between core and peripheral sutures. We then divided and repaired 27 flexor digitorum profundus tendons in 6 ways (core plus peripheral or peripheral sutures only at 1 mm, 2 mm, or 3 mm from the repair site). Tendons were clamped to a custom-built linear loading machine and distracted to failure.

Results: There was a clinically and statistically significant increase in strength with an increased distance of the peripheral suture from the repair site showing that core sutures augmented by a 2-mm peripheral repair were stronger than those performed with 1-mm peripheral repairs (50.8 vs 37.1 N).

Conclusions: A peripheral stitch placement approximately 2 mm from the repair site represents a simple modification that can significantly increase the ultimate strength of flexor tendon repairs.