Suture Tying Force for Cut-Out during Radial Meniscus Tear Repair: A Biomechanical Evaluation of Failure Loads during the Knot-Tying Process.

Objective: The purpose of the study was to determine average tensile forces resulting in suture failure while tying a knot during repair of complete radial meniscus tears and to compare the failure tensile force based on meniscus tissue location: the peripheral (red-red) versus inner (white-white).

Design: This study was designed as a cadaveric biomechanical study using 24 menisci harvested from fresh frozen cadaveric knees with midbody radial tears. Tears were repaired using 2-0 nonabsorbable suture in both the inner meniscus and the peripheral meniscus. A force gauge was used to measure the tension of a surgeon's knot until failure of either the suture or the meniscus tissue. Statistical analysis was performed comparing suture failure tensile forces between inner and peripheral sutures using 2-sample t test.

Results: Suture repairs primarily failed due to meniscal tissue cut-out after suture tensioning (96%). There was no statistical difference in failure mode between medial and lateral meniscus for both the inner (100% cut-out) and the peripheral (92% cut-out; P = 0.703) sutures. The peripheral sutures failed as significantly higher loads (54 ± 26 N) than the inner sutures (36 ± 11 N, P = 0.006). The peripheral meniscus tissue tolerated significantly higher tension at failure (36 ± 7 N) than the inner meniscus (26 ± 7 N, P < 0.001).

Conclusion: When tying parallel sutures to repair a radial meniscus tear, suture tensile forces above 30 N may tear through meniscus tissue. Surgeons should not use suture tying forces above 30 N when repairing radial meniscus tears with parallel sutures. The peripheral meniscus can withstand higher knot-tying forces than the inner meniscus, so surgeons should consider tying the peripheral suture before the inner suture.