Purpose: Tibial slope is an important contributor to sagittal plane stability. Anterior opening wedge high tibial osteotomy (HTO) has received increased attention for sagittal plane correction. A previous study demonstrated that anterior opening wedge HTO induced no increased strain in the ACL [1]. The goal of this present study was to determine the effect of increasing tibial slope on the strains of the major ligamentous restraints of the knee and on the change in position of the tibia in relation to the femur.

Method: Six cadaveric knee specimens were mounted at 15 degrees of flexion in a testing apparatus providing both compressive and anterior loading. Strains were measured in the ACL, PCL, MCL, and LCL for six randomized loading combinations and 3 conditions: intact, after anterior opening wedge HTO with 5mm plate, and 10mm plate. Tibial translation, rotation measurements and tibial slopes were obtained for each test.

Results: ACL strain was significantly associated with the plating intervention (p< 0.001). ACL strain decreased from −0.66 +/− 1.48 at baseline to −7.44 +/− 6.60 with a 5mm anterior opening wedge HTO and −7.99 +/− 6.45 with a 10mm osteotomy. Stepwise regressions yielded no significant effect of compression, anterior loading or osteotomy or combination thereof on PCL, MCL or LCL strain. Tibial slope and external rotation were significantly correlated with the plating intervention (p< 0.001 for both).

Conclusion: Increasing posterior slope via HTO did not increase strain in any of the major ligamentous restraints of the knee. Increasing tibial slope in the setting of a ligamentous deficient knee can be performed to increase stability without fear of submitting ligaments to increased strain.