Internal tibial torsion is associated with medial meniscus posterior horn tears

Purpose: Risk factors for meniscal tears play a decisive role in deciding on treatment and rehabilitation. The purpose of this study was to investigate the effect of tibial rotation on medial meniscus posterior horn tears (MMPHTs). Methods: This study is a retrospective case–control study. Fifty patients with meniscal tears and 57 knees with intact meniscus were compared. Tibial rotation, femoral version, tibial slope and knee varus were measured in each participant. Knee osteoarthritis was classified according to the Kellgren–Lawrence classification. Demographic characteristics were noted. Results: There were significant differences in the mean tibial torsion angles and mean mechanical axes between the groups. The mean tibial rotation and mean mechanical axis were 26.3° ± 6.7 and 3.7° ± 2.7 in the MMPHT group and 30.3° ± 8.4 and 2.05° ± 2.7 in the control group, respectively (p = 0.008, p = 0.002). Conclusion: The current retrospective study has shown that tibial rotation is markedly reduced in patients with MMPHTs. Although the actual mechanism is not clear, the internal torsion of the tibia causes a decrease in the foot progression angle and increases the knee adduction moment, which in turn increases the medial tibial contact pressure. Internal torsion of the tibia, such as knee varus, may play a role in the aetiology of MMPHTs by this way. Whilst there was a significant difference in the mean varus and tibial torsion between the groups, there was no significant difference in the mean femoral version or tibial slope. Level of evidence: III.