Prevalence, Development, and Factors Associated with Cyst Formation after Meniscal Repair with the All-Inside Suture Device

AIMS AND OBJECTIVES: The aim of this study is to investigate the prevalence of cyst formation as a complication of all-inside meniscal suture device using magnetic resonance imaging (MRI) and analyze the risk factors. MATERIALS AND METHODS: Of the patients who had undergone meniscal repair surgery 46 cases (46 knees) were selected to be in the case-control study. 51 menisci (34 medial menisci, 17 lateral menisci) of 46 cases were included to the study. Out of 51 menisci, 46 menisci combined anterior cruciate ligament (ACL) ruptures and had performed ACL reconstruction (ACLR). 5 cases (5 menisci) had been performed meniscal repair (MR). MRIs of the knee were performed 6, 12 and 24 months post-meniscal surgery. The MRIs were examined to detect the new development of cysts encasing the suture anchors and evaluate meniscal healing. Univariate and multivariate risk factor analyses was used to account for the suture technique (suture device alone versus suture device and inside-out suture repair), concurrent operation (MR alone versus MR with ACL reconstruction), patient gender, medial versus lateral menisci, number of device use, side-to-side difference of knee arthrometer, type of anchor (acetal resin versus PEEK material) and clinical scores (Lysholm score, Tegner activity scale, IKDC score). RESULTS: MRI examinations revealed cyst formation in 15 of 51 menisci. 3 menisci were detected cyst formation at 6 months of surgery, 9 at 12 months and 3 at 24 months. Only 3 patients (6.5%) were symptomatic. Tecxhniques using suture device alone was more likely to develop cysts: odds ratio (OR) was 10.67 (95% confidence interval (CI) 1.25 to 91.41). Medial meniscus statistically tended to develop cyst compared with lateral meniscus and OR was 7.92 (95% confidence interval (CI) 1.23 to 51.07). Patients who have instability (side-to-side difference of knee arthrometer > 3mm) are more likely to develop cysts than that ofless than or equal to 3mm (p = 0.06). CONCLUSION: This study revealed the risk factors and prevalence rate for cyst formation after using the all-inside meniscal suture device. The prevalence rate of cyst formation around suture implant was 29%, however most cases didn’t have any symptoms. Suture device only and medial meniscus were significant risk factors for cyst formation. Knee instability was greater in the cyst developed menisci though it was not significant, which suggested that knee instability could affect cyst formation around suture anchors.