Biomechanical Comparison of 3 Suturing Techniques for Lateral Meniscus Radial Tears Using a 6 Degrees of Freedom Robotic Simulator.

Background: Many different suture methods have been devised for lateral meniscus radial tears but have resulted in inconsistent outcomes. Purpose/Hypothesis: The purpose of this study was to compare the biomechanical performance, specifically resultant force, tibial shift, and rotation, of 3 suturing techniques-horizontal, tie-grip, and cross-grip-for radial lateral meniscus tears across different flexion angles and under repetitive loading, using a 6 degrees of freedom (6-DOF) robotic simulator. It was hypothesized that the cross-grip suture would demonstrate superior biomechanical properties. Study Design: Controlled laboratory study. Methods: Fresh-frozen porcine right knees were mounted on a 6-DOF robotic simulator to mimic knee joint motion accurately. Meniscal conditions, including intact, radial tear, and horizontal, tie-grip, and cross-grip sutures, were tested on 6 specimens each in 2 experiments: (1) flexion-extension movement under valgus torque and (2) repetitive axial loading at 60° of flexion. The resultant force, which was defined as the net force transmitted through the knee joint, and the tibiofemoral relationship, which was defined as the tibial shifts and rotations relative to the femur, were recorded. Results: Radial tears reduced the resultant force on the lateral meniscus by 45% to 78% compared with intact. Horizontal, tie-grip, and cross-grip sutures restored resultant force to within 5% to 15% of intact levels, with cross-grip achieving the highest recovery. Radial tears caused medial shifts up to 2.15 mm and valgus rotations up to 4.88°, while sutures reduced these to within ±0.44 mm and ≤2.49°, respectively. After 300 loading cycles, sutured menisci maintained >90% of intact force, whereas radial tears declined to 33%. The cross-grip suture maintained the highest force values among the techniques. Sutures also limited abnormal tibial shifts and rotations, partially restoring joint stability. Conclusion: All 3 suture techniques effectively restored joint stability caused by radial lateral meniscus tears. The cross-grip suture showed the highest resultant force in dynamic testing, while all techniques demonstrated the same durability under repetitive loading. This is the first comparative study on the durability of meniscal sutures using a 6-DOF simulator, and it may provide new insights for future research on meniscal sutures. Clinical Relevance: The results of this study suggest that the cross-grip suture may be the preferred choice for competitive athletes with lateral meniscus radial tears who require high load tolerance.