title: Predictors for additional anterior cruciate ligament reconstruction: data from the Swedish national ACL register.
abstract: OBJECTIVE
  To identify predictors for additional anterior cruciate ligament (ACL) reconstruction.
  
  
  METHODS
  Patients from the Swedish national ACL register who underwent ACL reconstruction between January 2005 and February 2013 (follow-up duration 6-104 months) were included. Cox regression analyses included the following independent variables regarding primary injury: age, sex, time between injury and primary ACL reconstruction, activity at primary injury, concomitant injuries, injury side, graft type, and pre-surgery KOOS and EQ-5D scores.
  
  
  RESULTS
  Among ACL reconstruction procedures, 93% involved hamstring tendon (HT) autografts. Graft type did not predict additional ACL reconstruction. Final regression models only included patients with HT autograft (n = 20,824). Of these, 702 had revision and 591 contralateral ACL reconstructions. The 5-year post-operative rates of revision and contralateral ACL reconstruction were 4.3 and 3.8%, respectively. Significant predictors for additional ACL reconstruction were age (fourfold increased rate for <16-year-old patients vs. >35-year-old patients), time between injury and primary surgery (two to threefold increased rate for ACL reconstruction within 0-90 days vs. >365 days), and playing football at primary injury.
  
  
  CONCLUSIONS
  This study identified younger age, having ACL reconstruction early after the primary injury, and incurring the primary injury while playing football as the main predictors for revision and contralateral ACL reconstruction. This suggests that the rate of additional ACL reconstruction is increased in a selected group of young patients aiming to return to strenuous sports after primary surgery and should be taken into consideration when discussing primary ACL reconstruction, return to sports, and during post-surgery rehabilitation.
  
  
  METHODS
  II.
authors.affiliation: Department of Physiotherapy, Ryhov County Hospital, 551 85, Jönköping, Sweden. anne.faltstrom@lj.se.
authors.forename: Anne
authors.initials: A
authors.lastname: Fältström
authors.affiliation: Division of Physiotherapy, Department of Medical and Health Sciences, Linköping University, Linköping, Sweden.
authors.forename: Martin
authors.initials: M
authors.lastname: Hägglund
authors.affiliation: Division of Physiotherapy, Department of Medical and Health Sciences, Linköping University, Linköping, Sweden.
authors.forename: Henrik
authors.initials: H
authors.lastname: Magnusson
authors.affiliation: Capio Artro Clinic AB, Sophiahemmet, Stockholm, Sweden.
authors.forename: Magnus
authors.initials: M
authors.lastname: Forssblad
authors.affiliation: Division of Physiotherapy, Department of Medical and Health Sciences, Linköping University, Linköping, Sweden.
authors.forename: Joanna
authors.initials: J
authors.lastname: Kvist
mesh_terms: D000328:Adult; D016118:Anterior Cruciate Ligament / Q000601:surgery*; D000070598:Anterior Cruciate Ligament Injuries; D059549:Anterior Cruciate Ligament Reconstruction / Q000379:methods / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D007718:Knee Injuries / Q000453:epidemiology* / Q000601:surgery; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D012008:Recurrence; D012042:Registries; D012086:Reoperation; D013548:Sweden / Q000453:epidemiology; D055815:Young Adult
keywords: ACL reconstruction registry; Contralateral; Cox regression analyses; Ligament registry; Revision; Subsequent injury