Comparison of One- and Two-knot Techniques in Eight-Strand Flexor Tendon Repair Using Looped Sutures: A Biomechanical Study in a Porcine Model.

PURPOSE: This study aimed to compare the biomechanical properties of one-knot and two-knot configurations in eight-strand flexor tendon repair using looped sutures. The influence of knot-tying strategy on gap resistance and ultimate failure strength was evaluated using a standardized porcine Achilles tendon model.

METHODS: Sixteen fresh porcine Achilles tendons were transected and randomly assigned to one-knot or two-knot repair groups (n = 8 per group). Repairs were performed using an eight-strand core suture technique with a single 4-0 looped suture-based on a modified Adelaide repair. Biomechanical testing was conducted using a digital force gauge to measure the tensile force required to produce 1-, 2-, and 3-mm gap formations and ultimate failure load. Failure modes were visually assessed and categorized into three categories: suture breakage, knot failure, or suture pull-out.

RESULTS: The one-knot group demonstrated significantly higher tensile forces required for 1-mm (12.4 ± 4.5 N vs 6.8 ± 2.8 N, P = .011), 2-mm (20.4 ± 7.5 N vs 10.3 ± 3.8 N, P = .004), and 3-mm (28.0 ± 9.2 N vs 17.0 ± 5.4 N, P = .011) gap formation compared to the two-knot group. Mean ultimate failure load was 100.1 ± 11.5 N in the one-knot group and 91.1 ± 13.7 N in the two-knot group, with no significant difference between them (P = .175). Knot failure was predominant in the one-knot group (7 of 8), whereas suture breakage was the primary failure mode in the two-knot group (7 of 8).

CONCLUSIONS: The one-knot configuration provided superior gap resistance compared to the two-knot configuration in looped suture-based eight-strand flexor tendon repair. Both techniques achieved high ultimate failure strength.

CLINICAL RELEVANCE: In flexor tendon repairs using looped sutures, the one-knot configuration may offer improved mechanical stability during the early rehabilitation phase, potentially reducing the risk of gapping and adhesion formation.