Is Noncontact ACL Injury Associated with the Posterior Tibial and Meniscal Slope?

The risk of noncontact ACL injury reportedly is increased in patients with a greater posterior tibial slope (PTS), but clinical data are inconsistent. It is unclear whether the medial and lateral PTSs have a different impact on this connection. It also is unknown whether the meniscal slope (MS) is associated with ACL injury. Using MRI, we compared the medial and lateral PTSs and MSs separately in 55 matched pairs of patients with isolated noncontact ACL injuries and a control group. Neither the PTS nor the relative difference between the medial and lateral PTSs differed between groups. In contrast, the lateral MS was greater with ACL injuries: 2.0A degrees versus -2.7A degrees in males with and without ACL injury and 1.7A degrees versus -0.9 in females. Uninjured females had a greater PTS than males: 4.9A degrees versus 3.0A degrees in females and males medially, respectively; 5.7A degrees versus 4.0A degrees lateral. There is no obvious link between the medial or lateral PTSs and ACL injury, and there is no obvious link between the relative difference in the medial and lateral PTSs and noncontact ACL injury. However, a greater lateral MS may indicate a greater risk of injury. The PTS can differ between the genders but the average difference is small. Level II, prognostic study. See the Guidelines for Authors for a complete description of levels of evidence.