Higher body mass index, postoperative bracing, narrower femoral notch, and anterior tibial tunnel positioning are independent risk factors for cyclops syndrome following anterior cruciate ligament reconstruction

INTRODUCTION: Cyclops syndrome consists of the development of a fibrous nodule anterior to the anterior cruciate ligament (ACL) graft, resulting in femoral notch impingement with subsequent loss of knee extension and pain. The present study aims to investigate the incidence of cyclops syndrome in a Middle East population and to identify demographic, surgical, and radiological risk factors. METHODS: In this retrospective study, patients who underwent primary ACL reconstruction in a single institution between 2018 and 2022 were consecutively included. Symptomatic cyclops lesions (cyclops syndrome) were defined as the presence of fibrous tissue anterior to the graft (magnetic resonance imaging [MRI]) associated with pain and/or lack of knee extension. Several demographic, surgical, and radiological variables were examined; the following were among them, sex, body mass index (BMI), time injury to surgery, graft type and diameter, addition of lateral extra-articular procedure (LEAP), pre-operative activity level, meniscal lesions and treatments, bracing, deep venous thrombosis prophylaxis, tibial slope, femoral notch size, and tibial tunnel positioning. The overall incidence and re-operation rate for cyclops were estimated. A multivariate logistic regression model was used to identify risk factors and calculate odds ratios (ORs) and confidence intervals (CIs) for the single variables. RESULTS: 588 patients were included in the final analysis. Symptomatic cyclops lesions were seen in 60 patients (10.2%); the main symptoms leading to the diagnostic MRI were lack of extension (n = 27; 45%), pain (n = 29; 50%), and a combination of both (n = 3; 5%). Thirty-five (6%) patients were re-operated. The final identified independent risk factors were brace usage (p = 0.016; OR: 2.41, 95% CI: 1.18-4.94), higher BMI (p = 0.007; OR: 1.09, 95% CI: 1.02-1.16), narrower notch apex (p < 0.001, OR: 0.77, 95% CI: 0.67-0.89), and anterior tibial tunnel positioning (p < 0.001, OR: 4.15, 95% CI: 2.17-7.96). CONCLUSION: The incidence of cyclops syndrome in a cohort of patients in the Middle East is approximately 10.2% of primary ACL reconstructions, with a re-operation rate of around 6%. Identified risk factors included a higher BMI, the use of a brace after surgery, narrower notch apex, and anterior tibial tunnel position. No significant influence was observed for posterior tibial slope, sex, graft type and diameter, recourse to LEAP, and preoperative activity level. LEVEL OF EVIDENCE: III (cohort study).