Medial Meniscus Posterior Root Repair in Knees With ≥5° of Varus Alignment Is Associated With Greater Osteoarthritis Progression Compared With <5° Varus Alignment

Abstract

Background:

Despite advances in medial meniscus posterior root (MMPR) repair techniques over the past decade, concerns persist about subsequent osteoarthritis (OA) progression.

Purpose:

To assess postoperative progression to OA after isolated MMPR repair in patients with normal alignment versus varus alignment.

Study Design:

Case-control study; Level of evidence, 3.

Methods:

A total of 128 patients who underwent isolated MMPR repair with available pre- and postoperative radiographs were included. Patients were stratified by mechanical hip-knee-ankle (HKA) angle into normal alignment (<5°; n = 83) and varus alignment (≥5°; n = 45) groups. Radiographic assessments included HKA angle, OA grading using the Kellgren-Lawrence (KL) classification, joint space width (JSW), meniscal extrusion, and repair healing on magnetic resonance imaging (MRI). Postoperative patient-reported outcomes were assessed using the International Knee Documentation Committee (IKDC) score. Logistic regression identified independent predictors of OA progression, and Pearson correlations were used to examine relationships among patient, radiographic, and clinical variables.

Results:

After a minimum follow-up of 2 years, OA progression occurred in 32.5% of normal alignment knees and 53.3% of varus-aligned knees (P = .02), with varus alignment associated with 2.37-fold higher odds of progression (95% CI, 1.13-4.99). The mean postoperative JSW decreased significantly in both groups (P < .001), with a greater reduction in varus knees (P < .001). Postoperative MRI revealed failed root repairs in 24.4% of normal alignment knees and 88.5% of varus knees (P < .001), and conversion to total knee arthroplasty occurred in 2.4% and 15.6% of knees, respectively (P = .005). There was no significant difference in postoperative IKDC scores between groups (P = .8). Multivariable logistic regression identified varus alignment, higher preoperative KL grade, and lack of repair healing on MRI as significant risk factors for OA progression. Correlation analysis showed strong positive associations between pre- and postoperative KL grade (r = 0.77) and moderate negative correlations between postoperative KL and JSW (r = −0.44).

Conclusion:

Varus-aligned knees showed greater OA progression, higher rates of repair failure, and increased conversion to arthroplasty, despite similar patient-reported outcomes. The multivariable logistic regression model identified varus alignment, higher preoperative KL grade, and lack of repair healing on MRI as significant risk factors for OA progression. These findings highlight the critical impact of baseline alignment and repair integrity on postoperative joint survival.