Steeper Slope of the Medial Tibial Plateau, Greater Varus Alignment, and Narrower Intercondylar Distance and Notch Width Increase Risk for Medial Meniscus Posterior Root Tears: A Systematic Review.

Purpose: To evaluate the available literature on the relationship between knee bony morphology and medial meniscus posterior root tears (MMPRTs) to determine which underlying tibiofemoral morphologic risk factors may predispose the development of MMPRTs.

Methods: Embase, MEDLINE, and PubMed databases were searched to identify all relevant human clinical studies investigating knee morphologic features and MMPRTs. Shape features were compared between control groups and patients with MMPRTs. The methodological index for non-randomized studies (MINORS) instrument was utilized to assess the methodological quality of included studies.

Results: Thirteen level III evidence studies and one level IV evidence study were included in this review (n=2,181), with 895 patients in the MMPRT group and 1,286 in the control group. Tibial morphology features associated with an increased risk for MMPRTs included an increased medial tibial slope (six studies), increased tibial torsion (one study), increased medial meniscal slope (one study), and shallower medial tibial plateau concavity (one study). Varus mechanical alignment was found to increase the risk for MMPRTs (four studies). Femoral morphology features associated with an increased risk for MMPRTs included an A-type intercondylar notch (one study), increased medial femoral condyle (MFC) angle (one study), narrower intercondylar distance (one study), narrower intercondylar notch width (one study), shorter MFC distal offset distance (one study), increased MFC width (one study), increased MFC to medial tibial condyle width ratio (one study), greater distance between the medial tibial eminence and MFC (one study), and smaller femoral offset ratios of both the medial and lateral condyles (one study).

Conclusion: Multiple tibiofemoral shape features, including a steeper slope of the medial tibial plateau, greater varus alignment, and a narrower intercondylar distance and notch width, were found to be predictive factors for MMPRTs.

Level of evidence: Level IV (Systematic review of Level III and IV studies).