Optimum location of knot for tendon surgery in side-locking loop technique

Background Although various tendon repair techniques have been reported to achieve stronger repair, suture failures tend to occur near the knot. We experimentally investigated whether the location of a single core suture knot affects the biomechanical properties of the repair. Methods Transected bovine tendons (male Japanese black cattle, 24 months old) of the medial gastrocnemius (9–11 × 14–16 mm in diameter) were sutured with the side-locking loop technique using a USP2-sized polyethylene and polyester multifilament suture or polyester multifilament suture. The knot was made using 7 simple square ties (a surgeon’s knot plus 5 ties) at three locations; on the loop, between the tendon stumps, or between the loops burying the knot in a tendon slit using a scalpel. A cyclical loading protocol from 10 N to 100 N was used and the loading was repeated 10,000 times. Findings The gap was most decreased and the ultimate strength was most increased when the knot was located between the loops when using a polyethylene and polyester multifilament suture. Cross-sectional area of the tendon showed the ratio of the buried knot relative to the tendon was only 1.6–2.3%, and the polyethylene and polyester multifilament suture was very durable against frictional abrasion. Interpretation We found that the knot between the loops, buried in the bovine tendon provided the optimum results.