title: Intraarticular hip injection and early revision surgery following total hip arthroplasty: a retrospective cohort study.
abstract: OBJECTIVE
  Therapeutic intraarticular injections are used in the management of hip osteoarthritis (OA). Some studies suggest that their use increases the risk of infection and subsequent revision surgery after primary total hip arthroplasty (THA), while others do not. We undertook this study to clarify the relationship between prior intraarticular injection and the risk of complication in a subsequent primary THA.
  
  
  METHODS
  In a cohort of patients with hip OA who underwent a primary elective THA between 2002 and 2009, we identified those who received ≥1 intraarticular injection performed by a radiologist in the 5 years preceding their THA. Multivariable Cox proportional hazards models were used to determine the relationship between receipt of a presurgical injection (no injection, 1-5 years prior to THA, or <1 year prior to THA) and the occurrence of postsurgical joint infection and revision THA in the following 2 years, while controlling for confounders.
  
  
  RESULTS
  Of 37,881 eligible THA recipients, 2,468 (6.5%) received an intraarticular injection performed by a radiologist within 5 years of their THA (1,691 at <1 year, 777 at 1-5 years). Controlling for age, sex, comorbidity, frailty, income, and provider volume, those who had an injection in the year preceding surgery were at increased risk of infection (adjusted hazard ratio [HR] 1.37, P = 0.03) and revision THA (adjusted HR 1.53, P = 0.03) within 2 years of the primary THA, relative to patients who did not. The association between prior injection and revision arthroplasty was attenuated and became nonsignificant (adjusted HR 1.41, P = 0.13) after occurrence of postoperative infection was controlled for in the regression model. No effect was found for injection 1-5 years prior to surgery.
  
  
  CONCLUSIONS
  Intraarticular injection in the year preceding THA independently predicted increased risk of infection leading to early revision surgery. Further studies are warranted to elucidate explanations for these findings.
authors.affiliation: University of Toronto, Toronto, Ontario, Canada.
authors.forename: Bheeshma
authors.initials: B
authors.lastname: Ravi
authors.forename: Benjamin G
authors.initials: BG
authors.lastname: Escott
authors.forename: David
authors.initials: D
authors.lastname: Wasserstein
authors.forename: Ruth
authors.initials: R
authors.lastname: Croxford
authors.forename: Simon
authors.initials: S
authors.lastname: Hollands
authors.forename: J Michael
authors.initials: JM
authors.lastname: Paterson
authors.forename: Hans J
authors.initials: HJ
authors.lastname: Kreder
authors.forename: Gillian A
authors.initials: GA
authors.lastname: Hawker
mesh_terms: D000305:Adrenal Cortex Hormones / Q000008:administration & dosage* / Q000627:therapeutic use; D000368:Aged; D019644:Arthroplasty, Replacement, Hip; D001424:Bacterial Infections / Q000453:epidemiology*; D015331:Cohort Studies; D005260:Female; D006621:Hip Joint / Q000382:microbiology / Q000601:surgery*; D006801:Humans; D006820:Hyaluronic Acid / Q000008:administration & dosage* / Q000627:therapeutic use; D007270:Injections, Intra-Articular / Q000009:adverse effects*; D008297:Male; D008875:Middle Aged; D009864:Ontario; D015207:Osteoarthritis, Hip / Q000628:therapy*; D011183:Postoperative Complications / Q000453:epidemiology; D011184:Postoperative Period; D057234:Preoperative Period; D016016:Proportional Hazards Models; D012086:Reoperation; D012189:Retrospective Studies; D012307:Risk Factors; D016896:Treatment Outcome
chemical_list: D000305:Adrenal Cortex Hormones; D006820:Hyaluronic Acid