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PURPOSE: To investigate the failure rate, predictive factors associated with failure and clinical outcomes after a two-stage surgery; meniscus repair followed by subsequent anterior cruciate ligament (ACL) reconstruction (ACLR).

METHODS: Patients with a concomitant traumatic meniscus tear and ACL injury who underwent a two-stage surgery between January 2015 and January 2021 were identified. The primary outcome was meniscal repair failure, defined as a reoperation (re-repair or resection). A Cox-regression analysis was used in order to analyse factors associated with meniscal repair failure within 3 years after the primary surgery for a meniscal repair. Secondary outcomes were range of motion (ROM), anterior knee laxity and the Knee Injury and Osteoarthritis Outcome Score (KOOS) at 1- and 2-year follow-up. The thresholds of patient acceptable symptom state (PASS), treatment failure (TF) and minimum important change (MIC) were applied to KOOS4 (mean score of the KOOS Pain, Symptoms, Sports/Rec and QoL subscales).

RESULTS: A total of 150 patients were included. The meniscal repair failure rate after 3 years was 36.7%. Failure of meniscal repair was significantly associated with a time interval >1 year between the meniscal repair to the ACLR (hazard ratio [HR] = 2.5; 95% confidence interval [CI] = 1.2-5.5; p < 0.01), medial meniscus repair (HR = 2.3; 95% CI = 1.6-3.4; P < 0.01), and female sex (HR = 1.42; 95% CI = 1.0-1.9; p = 0.01). The age of the patient was not associated with meniscal repair failure. At the 6-month follow-up, most patients (72.5%) showed less than 2 mm of knee laxity; four patients (6.7%) experienced loss of extension and four patients (1.7%) experienced loss of flexion. On the KOOS4, at the 2-year follow-up, PASS was achieved in 53.4%, TF occurred in 1.7%, and MIC was reached in 36.4% of patients.

CONCLUSION: The meniscus repair failure rate after the staged procedure was 36.7% at 3 years. A longer time interval from meniscal repair to ACLR, medial meniscus repair, and female sex were associated with an increased risk of meniscal repair failure. Age was not associated with meniscal repair failure.

LEVEL OF EVIDENCE: Level IV case series retrospective study.