title: Revision Risk After Allograft Anterior Cruciate Ligament Reconstruction: Association With Graft Processing Techniques, Patient Characteristics, and Graft Type.
abstract: BACKGROUND
  Allograft tissue is a common graft choice for anterior cruciate ligament reconstruction (ACLR). Allograft sterilization methods vary widely across numerous commercial tissue vendors. Multiple studies, despite being limited in sample size, have suggested a higher rate of clinical failure associated with the use of allograft tissue in ACLR when compared with autograft.
  
  
  OBJECTIVE
  To examine the association of graft processing techniques, patient characteristics, and graft type with risk of revision surgery after allograft ACLR.
  
  
  METHODS
  Cohort study; Level of evidence, 3.
  
  
  METHODS
  A retrospective cohort study was conducted that used an integrated United States health care system's ACLR registry to identify primary unilateral cases in which allografts were used. Aseptic revision was the endpoint of the study. Allograft type, processing methods (irradiation dose, AlloWash, AlloTrue, BioCleanse), and graft donor age were assessed as potential risk factors for revision, with adjustment for patient age, sex, and body mass index (BMI) by use of survival analysis. Hazard ratios (HR) and 95% confidence intervals (CIs) were calculated.
  
  
  RESULTS
  A total of 5968 primary ACLR cases with allograft were included in the study, of which 3688 (61.8%) were male patients. The median age of the cohort at the time of surgery was 34.1 years (interquartile range, 24.1-42.9 years). The mean time to follow-up (±SD) was 2.1 ± 1.5 years. There were 3751 (62.9%) allograft ACLRs using soft tissue, 1188 (19.9%) with Achilles tendon, and 1029 (17.2%) with bone-patellar tendon-bone (BPTB). Graft processing groups included BioCleanse (n = 367), AlloTrue or AlloWash (n = 2278), irradiation greater than 1.8 Mrad (n = 1146), irradiation up to 1.8 Mrad (n = 3637), and no irradiation (n = 1185). There were 156 (2.6%) aseptic revisions. After adjustment for patient age, sex, and BMI, the use of BioCleanse (HR = 2.45; 95% CI, 1.36-4.40) and irradiation greater than 1.8 Mrad (HR = 1.64; 95% CI, 1.08-2.49) were associated with a higher risk of revision when compared with all other methods of processing. BPTB allografts were at higher risk of revision (HR = 1.79; 95% CI, 1.20-2.66) when compared with soft tissue allografts. Conversely, with every 5-year increase in age, the risk of revision was 0.67 (95% CI, 0.61-0.73) times lower. Male patients were found to be at higher risk of revision when compared with females (HR = 1.47; 95% CI, 1.04-2.07). The use of AlloWash or AlloTrue processing, patient BMI, and graft donor age did not affect revision rate significantly.
  
  
  CONCLUSIONS
  In the largest known study of its kind examining outcome after primary allograft ACLR, graft irradiation greater than 1.8 Mrad, BioCleanse graft processing, younger patient age, male patients, and BPTB allograft were all associated with a higher risk of clinical failure and subsequent revision surgery.
authors.affiliation: Kaiser Permanente, Fontana, California, USA samir.g.tejwani@kp.org.
authors.forename: Samir G
authors.initials: SG
authors.lastname: Tejwani
authors.affiliation: Kaiser Permanente, San Diego, California, USA.
authors.forename: Jason
authors.initials: J
authors.lastname: Chen
authors.affiliation: Kaiser Permanente, Irvine, California, USA.
authors.forename: Tadashi T
authors.initials: TT
authors.lastname: Funahashi
authors.affiliation: Kaiser Permanente, San Diego, California, USA.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Love
authors.affiliation: Kaiser Permanente, Los Angeles, California, USA.
authors.forename: Gregory B
authors.initials: GB
authors.lastname: Maletis
mesh_terms: D000293:Adolescent; D000328:Adult; D064591:Allografts; D059549:Anterior Cruciate Ligament Reconstruction / Q000379:methods*; D015992:Body Mass Index; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017847:Patellar Ligament / Q000637:transplantation*; D016016:Proportional Hazards Models; D012042:Registries; D012086:Reoperation; D012189:Retrospective Studies; D012307:Risk Factors; D013242:Sterilization / Q000379:methods; D014184:Transplantation, Homologous; D014481:United States; D055815:Young Adult
keywords: ACL reconstruction; ACL registry; allograft; revision