Locking repairs for obliquely cut tendons: Effects of suture purchase and directions of locking circles

Oblique cuts in tendons weaken conventional repairs but locking sutures improve the repair strength of the tendon. In this study we assessed how suture purchase and direction (or type) of locking sutures affect the repair strength.

Ninety-three fresh pig flexor tendons were transected obliquely (45 degrees to the long axis of the tendon) and repaired with either a locking Kessler repair (with perpendicular or horizontal locking circles) or a locking cruciate method (with oblique locking or perpendicular locking circles). The suture purchase in the short side of the tendon stump with a perpendicular locking Kessler repair ranged from 0.3 to 1.2 cm. The gap formation and ultimate strength were measured to compare the biomechanical performance for each repair.

The repair strength increased significantly as the suture purchase increased from 0.3 to 1.0 cm in oblique tendon lacerations, with a suture span of 1.0 cm being the strongest. The strength decreased significantly when the span was 1.2 cm. The repairs with horizontal locking sutures were significantly weaker than those with perpendicular locking sutures. The locking cruciate repair with the perpendicular locking circles had strength identical to that of the cruciate with oblique locking circles.

Both suture purchase and the direction of locking circles affect the repair strength remarkably. For locking repairs the suture purchase of 1.0 cm in an obliquely cut tendon produced the highest strength; the repairs with a purchase less than 0.4 cm had significantly reduced strength. The strength of the repairs with locking circles perpendicular to the long axis of the tendon was significantly greater than that of the repairs with locking circles parallel to the long axis of the tendon.