Predictors of Long-term Patient-Reported Outcome Measures After Collagen Meniscal Implant for Partial Meniscal Defects
Authors: Grassi Alberto , Lucidi Gian Andrea , Di Paolo Stefano , Pierangeli Andrea , Agostinone Piero , Dal Fabbro Giacomo , Pizza Nicola , Zaffagnini Stefano 
Published: July 2024

Background: Collagen meniscal implant (CMI) is considered an effective procedure for reducing knee pain and improving knee function after previous meniscectomy. Nevertheless, the current knowledge regarding long-term patient reported-outcome measures after CMI is limited. Purpose: To evaluate clinical outcomes, reoperations, and failures of CMI at a minimum 10-year follow-up. Study Design: Case series; Level of evidence, 4. Methods: Consecutive patients who underwent CMI at a single institution were screened for eligibility. Inclusion criteria for the present study were (1) medial or lateral CMI; (2) isolated or combined procedure with anterior cruciate ligament reconstruction, knee osteotomy, or cartilage treatment; and (3) follow-up between 10 and 15 years. Demographics and surgical details were obtained via chart review. Patients were asked if they were satisfied with the procedure and were evaluated with the Lysholm score, Knee injury and Osteoarthritis Outcome Score (KOOS), visual analog scale for pain, and Tegner score at the final follow-up. Cases requiring partial or total scaffold removal for any reason (including scaffold breakage, infection, or surgery for osteoarthritis progression) were considered surgical failure. Survival analysis was performed with Kaplan-Meier curve, and clinical scores were analyzed based on the Patient Acceptable Symptom State (PASS). Results: A total of 92 patients (mean age, 42.2 years were included in the analysis. A significant improvement in all clinical scores was reported between the preoperative evaluation and the last follow-up. A chondropathy with Outerbridge grade ≥3 was associated with significantly overall lower clinical scores, while a timing from meniscectomy to CMI of ≥5 years determined more pain at rest and reduced Quality of Life in the KOOS subscale. No significant difference was found in terms of clinical scores between patients undergoing isolated and combined procedures. At the final follow-up, the mean Lysholm score was 76.3 points. In total, 12 cases (13%) were considered surgical failures. Sixteen patients (17%) did not reach PASS for the Lysholm score, with a total of 28 cases (30%) classified as clinical failures. Overall, 19% (KOOS Pain) and 40% (KOOS Symptoms) of patients did not achieve the PASS in the KOOS subscales. Chondropathy with Outerbridge grade ≥3 was associated with a higher risk of not achieving the PASS in all the KOOS subscales, while age at surgery of ≥45 years resulted in a lower risk of not achieving PASS in the Pain subscale. At the last follow-up, 63% of patients were still involved in sports activity, with 41% at the same or higher level. Finally, 80% of the patients were satisfied with the procedure. Conclusion: Up to 10 years after surgery, around 70% of the patients who underwent CMI reported satisfactory clinical results, with clinical subjective scores still higher compared with the preoperative evaluation. Overall, 30% of cases were considered clinical failures, with 13% considered surgical failures and 17% not meeting the PASS for the Lysholm score. In addition, cartilage status and time from meniscectomy were shown to have a negative impact on the outcomes, while an age ≥45 years was associated with less pain. There was no clinical difference between patients who underwent isolated CMI or combined procedures.