Summary

A multivariate model using retrospective data of primary ACL reconstructions demonstrated that knee hyperextension, and not graft type, graft diameter, or remnant preservation, is an independent predictor of cyclops syndrome.

Abstract

Background

Cyclops syndrome is a common yet poorly understood complication following anterior cruciate ligament reconstruction, resulting in loss of extension sometimes necessitating revision surgery for debridement. Limited agreement in the literature exists on the risk profile of patients who develop cyclops syndrome.

Purpose

To define a risk profile which predisposes individuals to developing cyclops syndrome necessitating reoperation after primary anterior cruciate ligament reconstruction.
Study Design: Retrospective Case-Control Study, Level IV.

Methods

Primary anterior cruciate ligament reconstructions performed by academic sports medicine surgeons at a single large integrated healthcare network between 2014 and 2021 were included. Variables including patient demographics, knee hyperextension, instability grade, graft type and diameter, meniscus procedures, femoral notch width, anterior cruciate ligament remnant preservation, graft/tissue impingement, tunnel position, and posterior tibial slope were collected. Univariate analyses and multiple regression were performed to identify risk factors associated with development of symptomatic cyclops syndrome, defined as requiring arthroscopic debridement of a cyclops lesion within 24 months following anterior cruciate ligament reconstruction.

Results

1,163 consecutive primary anterior cruciate ligament reconstructions were included (mean age: 24.9 years). The overall rate of cyclops syndrome was 5.5%. No statistically significant differences in rates of cyclops syndrome were identified based on surgical delay, graft type, graft diameter, or meniscus repair. Additionally, anterior cruciate ligament remnant grade, excessive graft anterior tissue coverage, and tibial tunnel position were not associated with development of cyclops syndrome. On univariate analyses, contralateral knee hyperextension (p = 0.04) and increased PTS >12 degrees (p = 0.004) were found to be potential risk factors for cyclops syndrome. Subset stepwise multiple regression analysis (n = 351) identified knee hyperextension as an independent predictor of ipsilateral development of cyclops syndrome (OR: 2.40; p = 0.049).

Conclusion

After controlling for posterior tibial slope, narrow femoral notch, and proximal femoral tunnel placement, contralateral knee hyperextension was found to be an independent predictor for the development of cyclops syndrome necessitating surgical debridement following primary anterior cruciate ligament reconstruction. Surgical delay, graft type, graft diameter, meniscus repair, remnant preservation, or excessive anterior graft tissue were not found to be associated with the development of cyclops syndrome.