title: Acute revision hip arthroplasty: a previously unrecognized risk factor for heterotopic ossification.
abstract: BACKGROUND
  The aim of this retrospective review was to determine the incidence and severity of heterotrophic ossification (HO) following acute revision total hip arthroplasty (THA), and whether this represents a significant risk factor for HO that should be treated prophylactically.
  
  
  METHODS
  A total of seven patients (three men and four women) with a mean age of 55 years (39-70 years) who underwent a reoperation of their THA for any reason that required a hip arthrotomy within 3 weeks of their primary or revision THA were included, with a mean follow-up of 8.8 years (2-12 years). All patients were evaluated radiographically for any evidence of HO and clinically using the Harris Hip Score.
  
  
  RESULTS
  All seven hips (100 %) developed HO, with 71 % being severe (Brooker III and IV HO). One hip (14 %) developed Brooker IV HO, four hips (57 %) developed Brooker III HO, and two hips (29 %) developed Brooker II HO. The patient's range of motion varied, but was very limited in three patients. Three patients (42.8 %) were not satisfied with their surgery; one patient had Brooker IV HO, and two patients had Brooker III HO.
  
  
  CONCLUSIONS
  Acute reoperation after primary or revision THA is a significant risk factor for the development of extensive HO, which requires prophylactic treatment.
authors.affiliation: Division of Orthopaedic Surgery, McGill University Health Centre, 1650 Cedar Avenue, B5.159, Montreal, QC, H3G 1A4, Canada. ajurayyan@gmail.com.
authors.forename: Abdulaziz
authors.initials: A
authors.lastname: Aljurayyan
authors.affiliation: Sackler Medical School, Tel Aviv University, Tel Aviv, Isreal.
authors.forename: Dylan
authors.initials: D
authors.lastname: Tanzer
authors.affiliation: Division of Orthopaedic Surgery, McGill University Health Centre, 1650 Cedar Avenue, B5.159, Montreal, QC, H3G 1A4, Canada. michael.tanzer@mcgill.ca.
authors.forename: Michael
authors.initials: M
authors.lastname: Tanzer
mesh_terms: D000328:Adult; D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009999:Ossification, Heterotopic / Q000209:etiology*; D012086:Reoperation; D012189:Retrospective Studies; D012307:Risk Factors
keywords: Acute; Complication; Heterotopic ossification; Hip arthroplasty; Revision