The purpose of this study was to describe a cohort of isolated medial meniscus posterior root tears (MMPRTs) and determine short-term clinical outcomes to 1) determine risk factors associated with clinical failures and 2) describe the surgical failure rates.
Isolated MMPRT repairs performed 2010-2019 at a single academic institution were reviewed. Clinical failure was defined as patients with International Knee Documentation Committee (IKDC) scores below the Patient Acceptable Symptomatic State (PASS) threshold of 75.9. Surgical failure was defined as root repair re-tear or conversion to arthroplasty. Additionally, pre-MMPRT and final Tegner activity level, pre- and postoperative Visual Analog Scale (VAS) were recorded.
Fifty-one isolated MMPRT repairs (35 females, 16 males, age: 46±12 years, BMI: 31±7 kg/m2) were followed for a mean of 3.1 years (range: 1.2-6.5 years). Mean pre-MMPRT Tegner prior to onset of knee symptoms was 5.1±1.7 and mean immediate preoperative VAS was 4.0±2.7 at rest and 6.0±2.6 with use. Preoperative meniscus extrusion was 3.5±0.9 mm (range: 1.5–5.3). Patients achieved significant postoperative improvements in VAS (p<0.001) and were able to regain Tegner scores of 4.4±1.7, which was statistically similar to their pre-injury levels (p=0.65). At final follow-up, patients with a discrete injury event (HR: 0.39, p=0.02), <4 mm of preoperative extrusion (HR: 2.6 for ≥4 mm extrusion, p=0.03), and preoperative Tegner ≥4 (HR: 0.12, p=0.12) were more likely to meet the IKDC-PASS threshold of 75.9. Two patients (4%) experienced a root repair re-tear, and two patients (4%) converted to arthroplasty at a mean of 4.5 years postoperatively.
Transtibial repair of isolated MMPRTs demonstrates significant improvements in preoperative VAS pain scores and restoration of pre-injury Tegner activity scores. Patients’ ability to achieve a postoperative IKDC-PASS threshold of 74.9 points is predicted by a discrete tear event, preoperative extrusion <4 mm, and high pre-injury activity level.