title: Patient predictors of early revision surgery after anterior cruciate ligament reconstruction: a cohort study of 16,930 patients with 2-year follow-up.
abstract: BACKGROUND
  Revision surgery is one of the most important endpoints during follow-up after anterior cruciate ligament (ACL) reconstruction.
  
  
  OBJECTIVE
  To investigate if commonly known patient factors can predict revision surgery after ACL reconstruction.
  
  
  METHODS
  Cohort study; Level of evidence, 2.
  
  
  METHODS
  This prospective cohort study was based on data from the Swedish National Knee Ligament Register during the period of January 1, 2005, through December 31, 2013. Patients who underwent primary ACL reconstruction with hamstring tendon or bone-patellar tendon-bone autografts were included. Follow-up started on the date of primary ACL reconstruction, and follow-up ended with ACL revision surgery, after 24 months of follow-up, or on December 31, 2013, whichever occurred first. The analyzed patient variables were activity at the time of injury, sex, age, height, weight, body mass index, smoking, and the use of smokeless tobacco. The primary study endpoint was revision surgery, defined as replacement of a primary ACL reconstruction. Relative risk (RR) and 95% CIs were calculated and adjusted for confounding factors using multivariate statistics.
  
  
  RESULTS
  A total of 16,930 patients were included (males, n=9767 [57.7%]; females, n=7163 [42.3%]). The 2-year revision rate was 1.82% (95% CI, 1.62%-2.02%). There was no significant difference between male and female revision rates (1.74% [95% CI, 1.48%-2.00%] vs 1.93% [95% CI, 1.61%-2.25%], P=.383). In both males and females there was a significantly increased risk of revision surgery associated with soccer playing and adolescence (age 13-19 years) (males: RR=1.58 [95% CI, 1.12-2.23], P=.009 and RR=2.67 [95% CI, 1.91-3.73], P<.001, respectively; females: RR=1.43 [1.01-2.04], P=.045 and RR=2.25 [95% CI, 1.57-3.24], P<.001, respectively). A combination of these predictors were associated with a further increased risk of revision surgery (males: RR=2.87 [95% CI, 1.79-4.60], P<.001; females: RR=2.59 [95% CI, 1.69-3.96], P<.001).
  
  
  CONCLUSIONS
  Soccer players and adolescents had an increased risk of revision surgery after ACL reconstruction, with a respective factor of 1.5 and 2.5. Individuals with a combination of these 2 predictors carried an almost 3-fold higher risk of revision surgery. There were no significant associations for sex, height, weight, body mass index, or tobacco use.
authors.affiliation: Vårdcentralen Gripen, Karlstad, Sweden Primary Care Research Unit, Centre for Clinical Research, County Council of Värmland, Karlstad, Sweden Department of Orthopaedics, Institute of Clinical Sciences, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden daniel.andernord@gmail.com.
authors.forename: Daniel
authors.initials: D
authors.lastname: Andernord
authors.affiliation: Department of Orthopaedics, Institute of Clinical Sciences, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden Department of Orthopaedics, Sahlgrenska University Hospital, Mölndal, Sweden.
authors.forename: Neel
authors.initials: N
authors.lastname: Desai
authors.affiliation: Department of Orthopaedics, Institute of Clinical Sciences, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden Department of Orthopaedics, Sahlgrenska University Hospital, Mölndal, Sweden.
authors.forename: Haukur
authors.initials: H
authors.lastname: Björnsson
authors.affiliation: Department of Orthopaedics, Institute of Clinical Sciences, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
authors.forename: Mattias
authors.initials: M
authors.lastname: Ylander
authors.affiliation: Department of Orthopaedics, Institute of Clinical Sciences, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden Department of Orthopaedics, Sahlgrenska University Hospital, Mölndal, Sweden.
authors.forename: Jón
authors.initials: J
authors.lastname: Karlsson
authors.affiliation: Department of Orthopaedics, Institute of Clinical Sciences, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden Department of Orthopaedics, Sahlgrenska University Hospital, Mölndal, Sweden.
authors.forename: Kristian
authors.initials: K
authors.lastname: Samuelsson
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D059549:Anterior Cruciate Ligament Reconstruction / Q000379:methods / Q000706:statistics & numerical data*; D050376:Bone-Patellar Tendon-Bone Grafting / Q000706:statistics & numerical data; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012042:Registries; D012086:Reoperation / Q000706:statistics & numerical data; D012307:Risk Factors; D012865:Skiing / Q000293:injuries* / Q000706:statistics & numerical data; D012916:Soccer / Q000293:injuries* / Q000706:statistics & numerical data; D013548:Sweden / Q000453:epidemiology; D013710:Tendons / Q000637:transplantation; D013997:Time Factors; D055815:Young Adult
keywords: age factors; anthropometry; autografts; body height; body mass index; body weight; bone–patellar tendon–bone; epidemiology; graft failure; graft survival; hamstring tendon; knee injury; registries; sex; smokeless tobacco; smoking; sports medicine; surgical revision