Incidence and Risk Factors for Meniscal Cyst After Meniscal Repair

Abstract

Purpose: To investigate the incidence of magnetic resonance imaging-confirmed cyst formation after meniscal repair and to analyze associated risk factors.

Methods: This retrospective study included cases repaired arthroscopically with the all-inside (AI) technique (using suture anchors) and/or the inside-out (IO) technique between October 2008 and December 2014. A meniscal cyst was detected on T2 fat-suppressed magnetic resonance images. All cases were divided into 3 groups according to the repair method (AI, IO, and combined technique). The incidence of radiographically confirmed meniscal cyst formation in each group and the associated risk factors (age, sex, AI device, medial meniscus, Tegner activity scale preinjury) were analyzed.

Results: A total of 102 menisci in 96 knees were evaluated. The mean follow-up period was 3.8 (range, 2-8) years. The mean patient age was 21.0 (range, 6-53) years. Thirty cases were in the AI group, 60 in the IO group, and 12 in the combined group. Demographically, there were significant differences among groups regarding the number of medial, lateral, and discoid tears; concomitant anterior cruciate ligament tears; Tegner scale; and suture number. Meniscal cysts developed in 14 of 102 cases. Two of the 14 cysts were symptomatic, requiring open cystectomy. The incidence of meniscal cyst was significantly higher in the AI group (12 of 30, 40%) than in the IO group (1 of 60, 1.7%) or the combined-technique group (1 of 12, 8.3%) (P < .001). Both symptomatic cysts were in the AI group and were in continuity with the anchors. Medial meniscus tear (odds ratio = 6.92) and the use of AI suture anchors (odds ratio = 15.03) significantly increased the risk of cyst formation.

Conclusions: The incidence of meniscal cysts after arthroscopic meniscal repair was 1.7% to 40.0%, depending on the surgical method. Medial meniscus tears and use of an AI device are suggested as risk factors for cyst formation in this retrospective study.

Level of evidence: Level Ⅲ, retrospective comparative study.