Purpose Meniscus repair has gained increasing interest over the last two decades as loss of meniscus tissue predisposes to early onset knee arthritis. Although there are many reports of meniscus repair outcome in short-term studies, data on the long-term outcome of meniscus repair are still scarce. The purpose of this meta-analysis was to evaluate the overall failure rate of meniscus repair with a minimum follow-up of 5 years. Additionally, possible factors influencing meniscus repair outcome were assessed. Methods PubMed and Scopus were searched for studies of the last 20 years reporting on meniscus repair outcome with a minimum follow-up of 5 years. The study was performed following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The search terms used for this study were ([meniscus OR meniscal] AND repair). Titles and abstracts were evaluated by two authors independently. Using meta package of R (version 3.6.2), random-effect models were performed to pool failure rates. Subgroup analyses were performed and effect estimates in form of an odds ratio with 95% CIs were established. Results In total, 12 studies with 864 patients were included. Degenerative tears were excluded in two studies and one study only included traumatic meniscus tears. Other studies did not state whether the cause of meniscus tear was degenerative or traumatic. Studies reporting meniscus repair outcome on root repairs, revision anterior cruciate ligament reconstruction, discoid menisci or ramp lesions were excluded. Revision surgery was used as failure definition in all included studies. The overall failure rate of meniscal repair at a mean follow-up of 86 months was 19.1%. There was no significant difference in meniscus repair outcome when performed in combination with anterior cruciate ligament reconstruction compared to isolated meniscus repair (18.7% vs. 28%; n.s.) or when performed on the lateral meniscus compared to the medial meniscus (19.5% vs. 24.4%; n.s.). There was no significant difference of meniscus repair outcome between vertical/longitudinal tears and bucket-handle tears (n.s.). Thirty-six percent of meniscus repair failures occur after the second postoperative year. The only significant finding was that inside-out repair results in a lower failure rate compared to all-inside repair (5.6% vs. 22.3%; p = 0.009) at 5 years. Conclusion The overall meniscus repair failure rate remains nineteen percent in long-term studies. The cause of failure is poorly documented, and it remains unclear whether failure of the meniscus repair itself or additional adjacent tears lead to revision surgery. Despite the given technical advantages of all-inside repair devices, this meta-analysis cannot demonstrate superior outcomes compared to inside-out or outside-in repair at 5 years. Level of evidence IV.

Background: The importance of meniscal repair is widely accepted because of the association of loss of meniscal tissue with the development of early-onset knee arthritis. Many factors influencing the results of meniscal repair have been reported, but results remain controversial. Purpose: This meta-analysis determines the pooled meniscal repair failure rate of studies with a minimum follow-up of 2 years up to 5 years, with a mean follow-up of 43 months. Moreover, selected failure-influencing factors are analyzed. Study Design: Systematic review and meta-analysis; Level of evidence, 4. Methods: PubMed and Scopus were searched for studies published between January 2000 and November 2021 reporting on meniscal repair outcome with a minimum follow-up of 24 months. The overall pooled failure rate and pooled failure rates for possible predictors were calculated. Random-effect models were used to pool failure rates, and effect estimates in the form of odds ratios with 95% CIs were established. Results: The initial literature search identified 6519 studies. A total of 51 studies met the inclusion criteria. In total, 3931 menisci were included with an overall failure rate of 14.8%. Subgroup analysis revealed a significantly lower failure rate for meniscal repair with concomitant anterior cruciate ligament (ACL) reconstruction compared with knees without any reported injury to the ACL (8.5% vs 14%; P = .043). The pooled failure rate for lateral meniscal repair was significantly lower than that for medial meniscal repair (6.1% vs 10.8%; P = .031). Pooled failure rates of all-inside and inside-out repair were not significantly different (11.9% vs 10.6%; P > .05). Conclusion: This meta-analysis on close to 4000 patients demonstrates an overall meniscal repair failure rate of 14.8% at a minimum follow-up from 2 years up to 5 years. Meniscal repair remains a procedure with a high failure rate, especially within the first 2 postoperative years. This review and meta-analysis also identified clinically relevant factors associated with favorable outcomes such as concomitant ACL reconstruction or repair of the lateral meniscus. All-inside meniscal repair with the latest-generation devices yields failure rates of <10%. The failure mechanism and the time of failure is poorly documented; further studies are needed for a better understanding of the retear mechanism.