title: Hamstring Contracture After ACL Reconstruction Is Associated With an Increased Risk of Cyclops Syndrome.
abstract: BACKGROUND
  Cyclops syndrome is characterized by loss of terminal knee extension due to proliferative fibrous nodule formation in the intercondylar notch. This complication occurs in the early postoperative period after anterior cruciate ligament reconstruction (ACLR). The pathogenesis of Cyclops syndrome is not well understood.
  
  
  OBJECTIVE
  Persistent hamstring contracture after ACLR is associated with an increased risk of subsequent Cyclops syndrome.
  
  
  METHODS
  Case-control study; Level of evidence, 3.
  
  
  METHODS
  The files of 45 patients who underwent arthroscopic debridement of a Cyclops lesion after ACLR were analyzed. Recorded data included demographic information and technical details of surgery. Preoperative magnetic resonance images were also analyzed, and patients with femoral bone bruising were identified. Passive and active range of motion were recorded in all patients preoperatively and at 3 and 6 weeks after surgery to address the Cyclops lesion. Passive extension deficit was evaluated in comparison with the contralateral limb and classified as secondary to hamstring contracture when contracture was observed and palpated in the prone position and when the extension deficit was reversed after exercises performed to fatigue the hamstrings. A control group was selected using a random numbers table among our entire ACLR cohort. Statistical analysis was performed to analyze differences between the 2 groups.
  
  
  RESULTS
  There was no significant difference between the groups with regard to age at ACLR, sex distribution, time from injury to surgery (P> .05), proportion of professional athletes, presence of femoral bone bruise, or technical aspects of surgery. The overall extension deficit incidence was significantly higher in the Cyclops group at 3 weeks (Cyclops, 71%; control, 22%) (P< .001) and at 6 weeks (Cyclops, 60%; control, 7%) (P< .001). The extension deficit related to hamstring contracture was significantly higher in the Cyclops group at 3 weeks (Cyclops, 58%; control, 22%) (P< .001) and at 6 weeks (Cyclops, 29%; control, 2%) (P< .001).
  
  
  CONCLUSIONS
  The Cyclops lesion is associated with a persistent hamstring contracture at 3 and 6 weeks after ACLR.
authors.affiliation: Hospital José de Almeida, Cascais, Portugal.
authors.forename: Francisco Guerra
authors.initials: FG
authors.lastname: Pinto
authors.affiliation: Centre Orthopédique Santy, FIFA Medical Center of Excellence, Générale de Santé, Hôpital Privé Jean Mermoz, Lyon, France.
authors.forename: Mathieu
authors.initials: M
authors.lastname: Thaunat
authors.affiliation: Kansas City University, Kansas City, Missouri, USA.
authors.forename: Matt
authors.initials: M
authors.lastname: Daggett
authors.affiliation: Centre Orthopédique Santy, FIFA Medical Center of Excellence, Générale de Santé, Hôpital Privé Jean Mermoz, Lyon, France.
authors.forename: Charles
authors.initials: C
authors.lastname: Kajetanek
authors.affiliation: Centre Orthopédique Santy, FIFA Medical Center of Excellence, Générale de Santé, Hôpital Privé Jean Mermoz, Lyon, France.
authors.forename: Tiago
authors.initials: T
authors.lastname: Marques
authors.affiliation: Centre Orthopédique Santy, FIFA Medical Center of Excellence, Générale de Santé, Hôpital Privé Jean Mermoz, Lyon, France.
authors.forename: Tales
authors.initials: T
authors.lastname: Guimares
authors.affiliation: Centre Orthopédique Santy, FIFA Medical Center of Excellence, Générale de Santé, Hôpital Privé Jean Mermoz, Lyon, France.
authors.forename: Bénédicte
authors.initials: B
authors.lastname: Quelard
authors.affiliation: Centre Orthopédique Santy, FIFA Medical Center of Excellence, Générale de Santé, Hôpital Privé Jean Mermoz, Lyon, France.
authors.forename: Bertrand
authors.initials: B
authors.lastname: Sonnery-Cottet
keywords: Cyclops syndrome; anterior cruciate ligament; hamstring contracture; knee; knee extension deficit; rehabilitation