High tibial osteotomy reduces tensile force at the repair site in medial meniscus posterior segment radial tears at 90° of knee flexion: A porcine biomechanical study.

OBJECTIVES

High tibial osteotomy (HTO) is a well-established treatment for medial meniscus (MM) tears with varus lower limb alignment. However, the effect of HTO on the distraction force at the repair site for MM radial tear remains unknown. This study measured the tensile force applied to the repair suture, used as a surrogate for the distraction force, before and after HTO.

METHODS

Ten fresh-frozen porcine knees were tested using a robotic system with 6 degrees of freedom and a load cell. Each knee was tested under two surgical conditions: MM repair (MMR) and MMR with HTO (MMR+HTO). A complete radial tear was created in the posterior segment, and repair was performed using a single-stitch horizontal suture. The tensile forces at the repair site were measured separately in the medial and lateral directions under an axial load of 300 N at 30°, 60°, and 90° of knee flexion.

RESULTS

At 90° of knee flexion, the tensile force (mean ± standard deviation) was 16.2 ± 1.9 N for MMR and 10.0 ± 3.7 N for MMR+HTO in the medial direction, and 15.7 ± 2.9 N and 9.0 ± 3.7 N, respectively, in the lateral direction. Two-factor repeated-measures analysis of variance demonstrated a statistically significant interaction between surgical condition and knee flexion angle (medial, p = 0.005; lateral, p = 0.002). MMR+HTO reduced the tensile force at 90° by 6.16 N (95% confidence interval [CI], 2.64 to 9.68; p = 0.003) in the medial direction and by 6.71 N (95% CI, 3.84 to 9.59; p < 0.001) in the lateral direction. No statistically significant differences were observed at 30° or 60° of knee flexion (all p ≥ 0.156).

CONCLUSION

HTO reduced the tensile force, used as a surrogate for the distraction force, at the repair site in MM posterior segment radial tears, particularly at 90° of knee flexion. These findings provide a preliminary biomechanical rationale for combining HTO with MMR in knees with medial compartment overload, and suggest that loaded deep flexion should be limited during early rehabilitation after repair of a posterior segment radial tear.

LEVEL OF EVIDENCE: Not Applicable, controlled laboratory study.