Paper 01: No differences in long-term survival after medial meniscus posterior root repair between low- and high-grade chondral changes

Objectives: To compare long-term survival and patient-reported outcomes (PROs) of medial meniscus posterior root repairs (MMPRR) based on intraoperative Outerbridge Classification grades. It was hypothesized that Outerbridge Classification grade 3-4 patients would have inferior survival of MMPRR and PROs compared to Outerbridge Classification grade 0-2 patients.
Methods: Consecutive skeletally mature patients undergoing primary isolated MMPRR performed at a single institution between January/2011 and September/2022 were included. Patients were categorized according to medial compartment arthroscopic chondral changes, defined as Outerbridge Classification grade 0-2 or 3-4, based on diagnostic arthroscopy at the time of surgery. Failure was defined as conversion to knee arthroplasty, high tibial osteotomy, or root retear. Data were collected through electronic medical record and/or prospectively distributed patient surveys. Chi-squared tests were used to assess associations between categorical variables, while T-test and Rank sum tests were used for continuous variables, and Kaplan-Meier estimates were used to assess survival using log-rank test. P value was set at p<0.05.
Results: In total, 240 patients were identified, and 170 patients were included. Of those, 74 patients were grouped as Outerbridge grade 0-2, and 96 patients as Outerbridge grade 3-4. Mean follow-up time was 5 years. There were no significant differences between groups in terms of age, gender, and body mass index (Table 1). The overall median survival was 11 years (Figure 1), and the survival analysis revealed no statistically significant differences between groups (Figure 2). There was overall 80% survival at 7.5 years, with 80% survival at 8 years for Outerbridge grades 0-2 and 7 years for Outerbridge grades 3-4. The overall failure rate was 18%, with no significant differences between Outerbridge Classification grade groups, and a mean time to reoperation of 5 years. In terms of PROs, the mean preoperative International Knee Documentation Committee (IKDC) was 34+-17, while the mean postoperative IKDC was 63+-23. Mean change in IKDC was 31+-22, surpassing the minimal clinically important difference (MCID) of 11.5. Visual analog scale for pain (VAS) scores decreased from 6.2+-2.2 preoperatively to 3.1+-3.0 postoperatively, with no significant differences between Outerbridge Classification grade groups (Table 2).
Conclusions: This study demonstrated that long-term survival and clinical outcomes after MMPRR are comparable between patients with baseline low- and high-grade chondral damage, as defined by Outerbridge Classification grades 0-2 versus 3-4, respectively. There were no significant differences between Outerbridge Classification grade groups in terms of failure rate or survival, with an overall median survival of 11 years and an 80% survival rate at 7.5 years. Similarly, change in IKDC did not differ significantly between Outerbridge Classification grade groups, with both exceeding the MCID. The findings of this study suggest that MMPRR may yield durable survival and meaningful outcome improvements for patients with both low- and high-grade chondral changes.