Abstract
PURPOSE: Conventional techniques (medial collateral ligament + posterior oblique ligament reconstructions), such as those by Lind and LaPrade, do not fully restore native knee stability in severe medial injuries. This study aimed to determine the optimal tibial insertion site for an anteromedial (AM) reconstruction strand mimicking the deep medial collateral ligament (dMCL), to better control anteromedial rotatory instability (AMRI) in knees with complete medial injury (sMCL + dMCL + POL). METHODS: Twenty fresh-frozen cadaveric knees (13 female, 7 male donors; mean age: 80 years) were tested using Dyneelax® static laximeter at 30° of flexion. After standardised transections of the superficial MCL (sMCL), deep MCL (dMCL), and posterior oblique ligament (POL), each knee was reconstructed using a trifid flat graft including an AM strand. Knees were assigned to two groups based on the tibial insertion angle (α) between the AM strand and the sMCL: group α ≤ 20° (anatomical reconstruction) and group α > 20° (oblique isometric reconstruction). Anterior tibial translation (ATT), internal rotation (IR), and external rotation (ER) were measured under 200 N of force and 5 N-m torques. Residual laxities were calculated in both absolute and relative terms, compared to the intact state, and analysed using ANOVA and Student's t-tests. RESULTS: Both reconstruction techniques significantly reduced laxity compared to the transected state. However, group α > 20° showed significantly lower residual laxity for ATT (0.74 ± 0.58 mm vs. 1.30 ± 0.56 mm, p = 0.04) and for ER (0.35 ± 0.39° vs. 1.05 ± 0.89°, p = 0.04), with no significant difference for IR (p = 0.24). CONCLUSION: There is a trend toward better stability with a more oblique AM strand, which must be confirmed by further biomechanical studies. This trifid flat graft approach more accurately replicates the biomechanical function of the dMCL and anteromedial capsule, and could provide a refined strategy for reconstructing severe medial knee instability. LEVEL OF EVIDENCE: Level V, experimental cadaveric study.