Paper 31: Risk factors affecting the survival rate of Collagen Meniscus Implant (CMI) for partial meniscus deficiency. An analysis of 156 consecutive cases at a mean 10 years of follow-up

OBJECTIVES: The present study aimed to determine the factors that predict failure of meniscus scaffold implantation in a large series of patients treated at a single institution, to better refine the indications for surgery and better inform future patients. METHODS: 156 consecutive patients with a minimum 5-year follow-up who underwent isolate CMI scaffold implantation or combined procedures were included in the analysis. Demographic and surgical information were obtained via chart review. Patients with partial meniscal deficiency requiring CMI implant, who had an Outerbridge grade of at least 3 and also underwent an additional surgery were considered as “complex cases”. Patients were asked to complete the Lyshlom questionnaire and those with a “poor” Lysholm score (<65 points) were considered a clinical failure. Patients were also inquired regarding further reoperations on the ipsilateral knee during the follow-up period to determine the incidence of surgical failure, defined as partial or total scaffold removal. RESULTS: 156 patients (84%) with a mean age at surgery of 42.0 ± 11.1 were included in the final analysis at an average follow-up of 10.9 ± 4.3 years. The overall survival rate from surgical failure was 87.8%. When further evaluating the different subgroups of patients, an Outerbridge grade of III-IV (HR 3.8; P =.004) and lateral scaffold (HR, 3.2; P= .0048) were identified as risk factors In the specific, the overall survival rate of the medial scaffold was 90.4%, while the survival rate of the lateral one was 77.4%. Finally, 42 patients (26.9%) were considered either a surgical or clinical failure. In this case, risk factors identified were: an Outerbridge grade of III-IV (HR, 3.1; P =.000), and time from meniscectomy to scaffold greater than 10 years (HR, 2.7; P = .042). CONCLUSIONS: Collagen meniscus implant for partial meniscus deficiency provided good long-term results, with 87.8% of the implants still in-situ at a mean 10.9 years of follow-up. The cartilage status, laterality of the scaffold, and time from meniscectomy to CMI surgery were identified to affect significantly clinical and/or surgical failures.