Long-term Subjective, Clinical, and Radiographic Outcome Evaluation of Meniscal Allograft Transplantation in the Knee

Background: Although meniscal allograft transplantation (MAT) has been performed for nearly 30 years, there are few long-term published studies of the technique. Hypothesis/Purpose: The goal of this study was to report the long-term results of a patient cohort whose medium-term results have been reported and to evaluate whether the results are maintained in the long term or deteriorate after a certain period. The hypothesis was that the subjective, clinical, and radiographic results are consistent in the long term without significant deterioration. Study Design: Case series; Level of evidence, 4. Methods: Thirty patients from the original cohort of 49 patients (50 MATs) who underwent MAT at least 9 years before this study were evaluated with the Knee injury and Osteoarthritis Outcome Score (KOOS); Lysholm, Tegner, and Short Form-36 scores; and a visual analog score for pain. A standardized clinical examination was performed to objectively evaluate knee-related symptoms. Standard weightbearing radiographs, including a full-leg standing radiograph, were performed to evaluate joint space narrowing and any progression of osteoarthritis and malalignment. These results, at a mean follow-up time of 12 years and 8 months (152 months; range, 112-216 months), were compared with the preoperative data and the outcome results at medium-term follow-up (mean, 8 years and 9 months). Results: Of the original 49 patients, 6 (12.2%) required conversion to a total knee arthroplasty during the study period and were considered failures, and 17 (34.7%) required a second surgical procedure during the study period. Excluding the 6 total knee arthroplasty cases, 90% of patients reported being very satisfied or satisfied and would undergo the procedure again. Only 1 patient reported not wanting to undergo the procedure again. Results of the visual analog score, KOOS and all KOOS subscales, Lysholm, and Short Form-36 all showed a statistically significant improvement at estimated follow-up periods of 7.5 and 12.5 years compared with preoperative scores. There was no statistically significant difference for these scores between 7.5 and 12.5 years postoperatively. Despite the improvement in outcome scores, the Tegner activity level score remained unchanged during the entire follow-up period. Regarding radiographic outcomes, there was a progressive increase in the Kellgren-Lawrence rating over the study period. There was a statistically significant (P = .0208) progressive joint space narrowing between estimates at the 7.5-year (5.45 mm) and 12.5-year (4.95 mm) follow-up. However, there was no statistically significant (P = .6724) difference in absolute value of alignment deviation from the 0 degrees mechanical axis between 7.5 years (2.32 degrees) and 12.5 years (2.51 degrees) postoperatively. There was no difference between medial and lateral transplants. Conclusion: Despite an increase in joint space narrowing, MAT resulted in significant improvements in pain and functional outcomes over the study period. There was no change in these improvements between the medium-and long-term follow-up period. This study confirms the good and consistent results found in the literature concerning satisfaction, pain resolution, and functional scores at long-term follow-up.