How much does a Pennington lock add to strength of a tendon repair?

Pennington advocated adding locking components to the Kessler-type repair to increase the repair strength, but did not actually test the repairs with this lock. Subsequent investigators have extensively cited that a Pennington lock is beneficial to the gain of repair strength. Thirty-three tendons were used to determine the exact strength differences between two grasping Kessler repairs and a Kessler repair with Pennington locks complemented with running peripheral suture. Two types of grasping repairs only had slightly lower resistance to gap formation compared with the repair with Pennington locks, and their ultimate strengths were not significantly different. We also compared the strength of four-strand Kessler repair with and without Pennington locks using 20 tendons, and found no difference in either gapping or ultimate strength. We conclude that a Pennington lock adds only a little to the capacity to gap resistance of a repair, but does not increase the ultimate strength.