The Effect of Suture Preloading on the Force to Failure and Gap Formation After Flexor Tendon Repair

Purpose Gap formation is a common and severe complication after flexor tendon repair that can affect the outcome and prolong tendon healing. The purpose of this study was to investigate the effect that a pretensional force applied to the suture during tendon repair has on the repair strength and force that causes gap formation. Methods We used a total of 48 flexor digitorum profundus tendons from 12 human cadaver hands. We employed a core tendon suture, using the modified Pennington technique, and a running suture for flexor tendon repair. Before tying the knots of the core suture, we preloaded the sutures in each tendon end 0, 5, 10, or 15 N for 10 seconds to compare the effect of loading magnitude on repaired tendon peak force to failure and force causing gap formation. Results The force to form a gap of 2 mm in the 15-N preload group was significantly increased compared with the 0-N and 5-N preload groups. At the 3-mm gap formation, the force of all preload groups was significantly higher than the nonpreload group. The peak force with a preload of 10 N and 15 N was significantly higher than 0-N preload. Conclusions These findings suggest that pretensioning with 10 to 15 N at the suture–tendon interface before tying the knot has a beneficial effect on both the tendon gap formation and the peak force to failure. Clinical relevance When the surgeons perform tendon repair, pretensioning at the suture–tendon conjunction will increase the repair strength.