Lengthening and locking: two ways to improve repair strength of obliquely lacerated tendons

PURPOSE: Oblique transections in tendons tend to reduce the strength of conventional repairs. We evaluated the effectiveness of lengthening longitudinal strand passage and adding locking components to improve the strength. METHODS: Seventy-six fresh pig flexor tendons were transected obliquely and repaired using either a modified Kessler (grasping) repair or a locking Kessler repair. Orientations of the strands within the tendon were varied among conventional, oblique, and lengthened. The 2-mm gap formation force and ultimate strength were tested as measures of biomechanical performance for each repair. RESULTS: The 2-mm gap formation force and ultimate strength with either grasping or locking repair were the weakest with a conventional repair, stronger with an oblique repair, and the strongest with a lengthened repair. The strength was significantly greater in oblique and lengthened locking repairs than in corresponding types of the grasping repair but was not different between the repairs with conventional configurations. CONCLUSIONS: Lengthening the repairs effectively improves the repair strength in obliquely lacerated tendons, in which strength of the conventional repairs diminishes owing to a decrease in the distance from sutures' grasping points to the laceration. Adding locking components increases the strength to oblique and lengthened repairs but does not add to the repairs with locking points that are not sufficiently away from the level of laceration.