Poster 231: Isolated Medial Meniscus Root Tears: A Multicenter Analysis of Prognostic Variables for Achieving Patient Acceptable Symptomatic State after Repair
Authors: Hevesi Mario , Boos Alexander M. , Wang Allen , Crowe Matthew , Economopoulos Kostas , Meta Fabien , Clark Sean , Stuart Michael J. , Krych Aaron J. , Simon Karissa N. 
Published: August 2024

Objectives: Medial meniscus posterior root tears (MMPRTs) render the meniscus essentially non-functional, resulting in increased peak contact pressures, reduced forced dissipation, and increased risk of early osteoarthritis. Transtibial root repair has shown promise at restoring meniscus function and improving clinical outcomes; however, a paucity of literature exists evaluating the prognostic clinical and radiographic factors for poor outcomes following isolated meniscus root repair. The purpose of this study was to 1) describe the patient reported clinical outcomes after isolated MMPRT repair at minimum 2-year follow-up, 2) determine the retear and conversion to arthroplasty rates, and 3) identify prognostic factors for clinical outcomes and International Knee Documentation Committee (IKDC) Patient Acceptable Symptom State (PASS) achievement. Methods: Isolated MMPRT repairs from 2010-2020 at three institutions in Rochester, MN; Jacksonville, FL; and Phoenix, AZ were followed prospectively for postoperative Tegner Activity Scale, Visual Analog Scale (VAS) for pain, IKDC, Forgotten Joint Score (FJS), subjective improvement and knee preference, and subsequent surgeries at minimum 2-year follow up. PASS for IKDC was set at 69. Demographics, injury characteristics, and surgical details were collected. Results: Eighty-four patients were included in this study (age: 49.7 ± 11.0 years [range: 13-76]; sex: 75.0% female; BMI: 31.6 ± 6.9 kg/m2[MH1] ). Forty-five patients (53.6%) had BMI >30 kg/m2, and 14 patients (16.7%) reported a history of active smoking (Table 1). Mean medial compartment Outerbridge grade was 2.0 ± 1.1, with 73.8% of patients having grade ≥2 changes. Mean preinjury Tegner score, preoperative VAS at rest, and preoperative VAS with use were 4.6 ± 2.4, 3.6 ± 2.7, and 6.5 ± 2.5, respectively. At final follow-up (mean 3.9 ± 2.0 years), mean Tegner score was 4.3 ± 1.8, mean VAS at rest was 1.2 ± 2.0, and mean VAS with use was 2.3 ± 2.2. There was no significant difference in preinjury vs. postoperative Tegner scores (p = 0.208), and preinjury Tegner was significantly positively correlated with postoperative Tegner (p < 0.001). Significant (p < 0.001) postoperative improvements in both VAS at rest and with use were observed. Mean postoperative IKDC score was 73.3 ± 17.0, and mean FJS was 59.6 ± 27.9 at final follow-up. When asked to rate their knee at final follow-up compared to before surgery on a scale from 0-5 (0 = “significantly worse”, 1 = “mildly worse”, 3 = “unchanged”, 4 = “mildly improved”, 5 = “significantly improved”), the mean score 4.6 ± 0.8. Forty-one patients (74.5%) reported significant improvement, 8 (14.5%) reported mild improvement, 3 (5.5%) reported no change, and 3 (5.5%) reported mild worsening. No patients reported significant worsening. When asked which knee they preferred, 13 patients (26.0%) reported preferring their operated knee, compared to 18 (36.0%) who preferred their nonoperated knee. The remaining 19 patients (38.0%) had no preference for one knee over the other. A summary of all patient reported outcomes is reported in Table 2. At the time of final follow-up, 16 (19.0%) of patients had reached a clinical endpoint. Twenty-nine patients (34.5%) underwent postoperative MRIs at an average of 1.5 ± 1.7 years (range: 0.3-5.9 years) after surgery[MH1] . Twelve of the MRIs (41.4%) were ordered for evaluation of continued pain, while 7 (24.1%) were ordered for new pain or injury, and 10 (34.5%) were ordered for research purposes. Five patients (6.0%) had MRI-confirmed retears of the MMPRT repair at an average of 1.1 ± 1.3 years (range: 0.3-3.4) after surgery[HMMP2] , one of which was in an asymptomatic patient who received a follow-up MRI for research purposes. No patients underwent revision MMPRT repair surgery, and 7 patients (8.3%) progressed to arthroplasty (6 TKA, 1 UKA) at an average of 3.4 ± 4.3 years (range 0.6-12.6), one of whom also sustained a root retear. Therefore, the surgical failure was noted in 11 patients, corresponding to a surgical failure rate of 13.1% in this cohort. Of note, three of the five patients with MRI-confirmed retears had not received any further surgical intervention[MH3] [BA(M4] at the time of final follow-up 2.7, 3.8, and 8.5 years after surgery. Additionally, there were six non-MMPRT revision, non-arthroplasty subsequent surgeries in five patients, and there were three patients (3.6%) who sustained new medial meniscus tears 2.8-, 3.6-, and 5.9-years postoperatively, respectively. A concise summary of clinical endpoints can be found in Table 3 and Table 4. Significantly more females experienced surgical failures than males (17.5% vs. 0%, p = 0.040), and significantly more patients with medial compartment Outerbridge grades ≥2 experienced surgical failure than those with grades <2 (17.7% vs. 0%, p = 0.034). Additionally, patients who failed did have significantly higher mean KL grades than those who did not (1.4 ± 0.9 vs. 0.7 ± 0.7, p = 0.012). There were no other significant differences in the demographic or pathologic characteristics of patients who experienced surgical failure and those who did not. Of note, 37% of patients failed to achieve IKDC PASS, with smoking status associated with a 15-point reduction in IKDC (p=0.010) Conclusions: Patients undergoing transtibial root repair demonstrate restoration of pre-injury activity levels, significant clinical improvements in pain and function, and low surgical failure rates at minimum 2-year follow-up, with 89% of patients reporting subjective improvement after surgery. However, only 63% of patients were able to achieve PASS thresholds, suggesting that while effective, additional research on root repair technical and clinical optimization is warranted.