Poster 264: Medial Tibia Bone Marrow Edema on Preoperative MRI Predicts Inferior Patient Outcomes Following Posterior Medial Meniscus Root Repair

OBJECTIVES: Repair of posterior medial meniscus root (PMMR) tears demonstrates favorable patient outcomes and may prevent rapid progression of knee osteoarthritis, however, there is a paucity of data in literature regarding prognostic factors affecting postoperative outcomes. The medial meniscus plays an important role in the knee biomechanically by increasing tibiofemoral contact area and decreasing peak tibiofemoral contact pressures. Few studies exist that examine preoperative knee magnetic resonance imaging (MRI) findings and patient reported outcome measures (PROMs) following PMMR repair. Semi-quantitative MRI evaluation can offer improved detection of degenerative pathology. Identifying specific factors that may predict surgical outcomes is important when considering PMMR repair, as some patients with more advanced degenerative joint disease may benefit from consideration for knee arthroplasty instead of joint preservation with meniscus repair surgery. The purpose of this study was to identify factors on preoperative MRI that may predict postoperative outcomes following PMMR repair. We hypothesize that patients with worse knee overall quality would have worse postoperative PRO scores. METHODS: Between 2012 and 2020, patients who underwent posterior medial meniscus root repair at a tertiary referral academic center by fellowship trained sports medicine surgeons were retrospectively identified, recruited, and enrolled in the study. Institutional review board approval and informed consent was obtained. Inclusion criteria included patients ages 18-70, posterior medial meniscus root repair through transtibial fixation technique, minimum two years postoperative follow-up, and a preoperative knee MRI. Exclusion criteria included prior ipsilateral knee meniscus or ligamentous injury, additional ipsilateral knee injury requiring surgery, and conversion to knee arthroplasty. Visual Analog Scale (VAS) pain and PRO surveys including Patient Reported Outcome Measures Information System Physical Function (PROMIS-PF) Computer Adaptive Test, Lysholm Knee Score, Knee Osteoarthritis and Injury Outcome Score (KOOS) with 5 sub-sections, were collected at minimum 2-years postoperative. Patient Acceptable State Score (PASS) values from a prior meniscus study were utilized to identify patients that met PASS for the KOOS subsections. A fellowship-trained musculoskeletal radiologist reviewed preoperative MRIs and calculated Whole Organ Magnetic Resonance Imaging Scores (WORMS) for meniscus, cartilage, bone marrow edema pattern (BMEP) in 6 knee locations as well as effusion/synovitis and meniscal extrusion. Radiographs were scored with Kellgren-Lawrence (KL) scores to assess presence and severity of osteoarthritis. Statistical analysis was performed with Stata (StataCorp) using two sample T-tests, Mann-Whitney, and Fisher’s exact test for categorical variables. Significance was defined as p<0.05. RESULTS: We evaluated 29 knees (22 female patients) with a mean age at surgery of 52.3±9.9 years, body mass index of 27.6±5.6 kg/m(2), and at a mean follow-up of 59.6 months ± 26.5. median KL grade 2, and 44.8% with meniscal extrusion. Pain scores decreased significantly from before surgery to final follow-up (p<0.001), and the percentage of patients meeting PASS ranged from 44.8% for KOOS-Sport subscale to 72.4% for KOOS-Pain and KOOS-Quality of Life subscales (Table 1). There were 10 patients with medial tibial BMEP on pre-operative MRI and 19 with no medial tibial BMEP (Table 2). Patients with medial tibia BMEP had significantly lower Lysholm Knee Score (p=0.037), KOOS-Symptoms (p=0.028), and KOOS-QOL (p=0.029) (Figure 1). There were no significant differences in demographics between those with and without medial tibia BMEP. There was no significant difference in PRO scores when comparing those with medial femoral condyle BMEP, cartilage quality in any of the knee regions, or presence of meniscus extrusion. CONCLUSIONS: We observed that patients with medial tibia BMEP at baseline on their preoperative MRI had inferior PROMs for Lysholm Knee Score, KOOS Symptoms, and KOOS-QOL after PMMR repair compared to those without medial tibia BMEP. The presence of medial tibial BMEP could represent underlying damage that may not be evident in the cartilage itself, given most medial tibia cartilage was normal on MRI and cartilage quality was not a significant discriminant for outcomes. The presence of meniscus extrusion did not correlate with patient outcomes either. Limitations of this study include only VAS-Pain score as a pre-operative measure. Multivariate analysis was not possible due to the sample size available. A strength of this study is the mean follow up of approximately 5 years and preoperative MRI data on all patients. Posterior medial meniscus root tears are generally treated with surgical repair due to increased risk of progression to arthritis, however, some patients continue to have symptoms after repair. Our results show that patients with medial tibial BMEP on their preoperative MRI have worse PRO scores after posterior medial meniscus root repair, which can help surgeons better counsel patients towards optimal treatment options. In conclusion, the presence of medial tibia BMEP on preoperative MRI was a marker for inferior patient outcomes for Lysholm Knee Score, KOOS Symptoms, and QOL at minimum two years postoperative following posterior medial meniscus root repair.