The Effects of Meniscal Geometry on Susceptibility for Meniscal and ACL Injury in Non-Arthritic Knees: A Retrospective Case-Control Study.

Abstract

Prior studies have not found significant differences in meniscal parameters between patients with meniscal and ligamentous injury and those without. The purpose of this study was to determine whether such relationships exist. Clinical records and magnetic resonance images of three subject groups were reviewed. Group 1 solely had meniscal tears (medial/lateral), Group 2 had meniscal tears with concurrent ACL tears, and Group 3 had healthy knees. The mean age of subjects included was 35.9 years (range 8.2-72.6). The height, width, diagonal, slope, and cross-sectional area for the anterior and posterior horns of the lateral and medial menisci were assessed. Normal distribution of data was confirmed by the Shapiro-Wilk test and analysis of variance with a post hoc Tukey's test was used to assess potential differences. p < 0.05 was set as the level of significance. There was no difference between the meniscal slopes of patients with and without meniscal tears (p = 0.77-1.0). Meniscal height (p = 0.0001-0.024) and width (p = 0.0001-0.046) demonstrated significant differences in all horns. Cross-sectional area was larger in the torn group (p = 0.0001-0.012). To compare intact and torn menisci, a logistical regression model was used and found to be significantly different from the constant model (p < 0.0001). Predictive success was 80.5%. A logistical regression model was used comparing undamaged menisci with torn menisci with accompanying anterior cruciate ligament (ACL) tear and was significant (p < 0.0001). A larger cross-sectional meniscal area in both the anterior and posterior horns of both menisci was a risk factor for isolated meniscal tears and combined meniscal and ACL tears. It has been postulated that certain demographic variables, such as gender, age, and body mass index, may be risk factors associated with ACL and meniscal injuries. However, the relationship between intrinsic morphology, namely meniscal size and shape, and risk of injury is unclear. The majority of studies have focused on meniscal morphology/geometry and its association with degenerative tears in patients with end-stage osteoarthritis rather than on acute meniscoligamentous injury. In this study of non-arthritic knees, a larger cross-sectional meniscal area in both the anterior and posterior horns of both menisci was a risk factor for having both an isolated meniscal tear as well as a combined meniscal and ACL tear. With advances in the field of meniscal repair, particularly with allograft procedures, more attention should be paid to meniscal cross-sectional area because it may play a role in the natural history of knee injury.