title: Differences in mechanisms of failure, intraoperative findings, and surgical characteristics between single- and multiple-revision ACL reconstructions: a MARS cohort study.
abstract: BACKGROUND
  The factors that lead to patients failing multiple anterior cruciate ligament (ACL) reconstructions are not well understood.
  
  
  OBJECTIVE
  Multiple-revision ACL reconstruction will have different characteristics than first-time revision in terms of previous and current graft selection, mode of failure, chondral/meniscal injuries, and surgical charactieristics.
  
  
  METHODS
  Case-control study; Level of evidence, 3.
  
  
  METHODS
  A prospective multicenter ACL revision database was utilized for the time period from March 2006 to June 2011. Patients were divided into those who underwent a single-revision ACL reconstruction and those who underwent multiple-revision ACL reconstructions. The primary outcome variable was Marx activity level. Primary data analyses between the groups included a comparison of graft type, perceived mechanism of failure, associated injury (meniscus, ligament, and cartilage), reconstruction type, and tunnel position. Data were compared by analysis of variance with a post hoc Tukey test.
  
  
  RESULTS
  A total of 1200 patients (58% men; median age, 26 years) were enrolled, with 1049 (87%) patients having a primary revision and 151 (13%) patients having a second or subsequent revision. Marx activity levels were significantly higher (9.77) in the primary-revision group than in those patients with multiple revisions (6.74). The most common cause of reruptures was a traumatic, noncontact ACL graft injury in 55% of primary-revision patients; 25% of patients had a nontraumatic, gradual-onset recurrent injury, and 11% had a traumatic, contact injury. In the multiple-revision group, a nontraumatic, gradual-onset injury was the most common cause of recurrence (47%), followed by traumatic noncontact (35%) and nontraumatic sudden onset (11%) (P < .01 between groups). Chondral injuries in the medial compartment were significantly more common in the multiple-revision group than in the single-revision group, as were chondral injuries in the patellofemoral compartment.
  
  
  CONCLUSIONS
  Patients with multiple-revision ACL reconstructions had lower activity levels, were more likely to have chondral injuries in the medial and patellofemoral compartments, and had a high rate of a nontraumatic, recurrent injury of their graft.
authors.affiliation: University of California, San Francisco, 1500 Owens Avenue, Box 3004, San Francisco, CA 94158, USA.
authors.forename: James L
authors.initials: JL
authors.lastname: Chen
authors.forename: Christina R
authors.initials: CR
authors.lastname: Allen
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Stephens
authors.forename: Amanda K
authors.initials: AK
authors.lastname: Haas
authors.forename: Laura J
authors.initials: LJ
authors.lastname: Huston
authors.forename: Rick W
authors.initials: RW
authors.lastname: Wright
authors.forename: Brian T
authors.initials: BT
authors.lastname: Feeley
mesh_terms: D000293:Adolescent; D000328:Adult; D059549:Anterior Cruciate Ligament Reconstruction / Q000706:statistics & numerical data*; D016022:Case-Control Studies; D002648:Child; D005260:Female; D006801:Humans; D007718:Knee Injuries / Q000453:epidemiology / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012086:Reoperation / Q000706:statistics & numerical data; D014182:Transplantation, Autologous / Q000706:statistics & numerical data; D014184:Transplantation, Homologous / Q000706:statistics & numerical data; D017211:Treatment Failure; D014481:United States / Q000453:epidemiology; D055815:Young Adult
keywords: ACL; ACL revision; allograft; autograft