title: Incidence and outcome after revision anterior cruciate ligament reconstruction: results from the Danish registry for knee ligament reconstructions.
abstract: BACKGROUND
  Revision anterior cruciate ligament (ACL) reconstruction is poorly described because of its rare incidence and mainly small case series presented in the literature. The Danish ACL reconstruction registry has monitored the development in revision ACL reconstruction since 2005.
  
  
  OBJECTIVE
  We hypothesized that younger patients had a higher risk of revision ACL reconstruction than older patients and that subjective clinical outcome was worse after revision ACL reconstruction than after primary ACL reconstruction.
  
  
  METHODS
  Cohort study; Level of evidence, 2.
  
  
  METHODS
  All clinics performing ACL reconstructions in Denmark report to the national ACL reconstruction registry. The revision rate after primary ACL reconstruction (n = 12,193 procedures) and re-revision rate after revision ACL reconstruction (n = 1099 procedures) were calculated for the period of 2005 to 2010. Outcome at 1-year follow-up for the revision cohort was reported using the Knee Injury and Osteoarthritis Outcome Score (KOOS), Tegner function score, and objective knee stability measurement.
  
  
  RESULTS
  The rate of revision ACL reconstruction was 4.1% after 5 years. Revision occurred most frequently after 1 to 2 years. Patients below 20 years of age at the time of primary ACL reconstruction had a higher risk of revision (8.7%) than did patients older than 20 years of age (2.8%) (adjusted relative risk, 2.58; 95% confidence interval, 2.02-3.30). The KOOS scores 1 year after revision ACL reconstruction (mean ± standard deviation) were 73 ± 18 for symptoms, 78 ± 17 for pain, 84 ± 16 for activities of daily living, 52 ± 28 for sports, and 48 ± 21 for quality of life. All these scores were significantly lower than for primary ACL reconstruction: 77 ± 17 for symptoms, 84 ± 15 for pain, 89 ± 13 for activities of daily living, 62 ± 25 for sports, and 59 ± 21 for quality of life. Side-to-side difference in knee laxity improved from 5.8 mm before revision ACL reconstruction to 1.9 mm 1 year after revision ACL surgery. The use of allograft tissue for the revision procedure resulted in a higher risk of re-revision than did autograft tissue (relative risk, 2.05; 95% confidence interval, 1.5-2.4) (P < .01). The rate of re-revision after 5 years was 5.4%.
  
  
  CONCLUSIONS
  In this observational population-based study, the 5-year revision ACL reconstruction rate was 4.1%. Despite achieving acceptable knee stability after revision ACL reconstruction, subjective outcome is less favorable than after primary ACL reconstruction.
authors.affiliation: Division of Sports Trauma, Aarhus University Hospital, Tage Hansens Gade 2, 8000 Aarhus C, Denmark. Martinlind@dadlnet.dk
authors.forename: Martin
authors.initials: M
authors.lastname: Lind
authors.forename: Frank
authors.initials: F
authors.lastname: Menhert
authors.forename: Alma B
authors.initials: AB
authors.lastname: Pedersen
mesh_terms: D000203:Activities of Daily Living; D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000070598:Anterior Cruciate Ligament Injuries; D059549:Anterior Cruciate Ligament Reconstruction / Q000009:adverse effects / Q000706:statistics & numerical data; D018771:Arthralgia / Q000209:etiology*; D003718:Denmark; D005260:Female; D006085:Graft Survival; D006801:Humans; D015994:Incidence; D007593:Joint Instability / Q000601:surgery; D007719:Knee Joint / Q000601:surgery*; D008297:Male; D012042:Registries; D012086:Reoperation; D014182:Transplantation, Autologous; D014184:Transplantation, Homologous; D016896:Treatment Outcome; D055815:Young Adult