The effect of locking loops on the strength of tendon repair.

A multiple X-raying method has been developed which allows examination of how the particular features of suturing techniques collapse or pull out of the tendon during tensile testing. This technique was used to examine the locking loop tendon sutures, such as the modified Kessler, Verdan and Ketchum techniques. Locking loops did not contribute towards the strength when small diameter sutures (5/0) of various materials were applied to the tendon, collapsing at 12 Newtons. Larger diameter sutures (4/0) slightly reduced the risk of failure of locking loops, but they still collapsed at 15 Newtons or less, so suture techniques which depend on locking loops will often lead to gap formation at low loads and hence poor results.