title: Heterotopic Ossification following acetabular fixation: Incidence and risk factors: 10-year experience of a tertiary centre.
abstract: BACKGROUND
  Heterotopic Ossification (HO) is a well-recognized complication following acetabular fracture fixation and its presence is prognostic for suboptimal clinical outcome. There are many controversies pertaining to its aetiology, including surgical approach, associated injuries and the use of HO prophylaxis. Long term data from high volume centres is necessary to address these issues.
  
  
  OBJECTIVE
  To determine the incidence of HO post open reduction and internal fixation (ORIF) of acetabular fractures and to examine the associated risk and prognostic factors.
  
  
  METHODS
  We studied a cohort of 369 consecutive acetabular fractures that underwent ORIF at our institution over a 10 year period. Data was analyzed using univariate and multivariate logistic regression.
  
  
  RESULTS
  The existence of HO was evident in 65 patients (17.62%), of these 39 (60.0%) were Class I, 16 (24.6%) were Class II, 8 (12.3%) were Class III, and 2 (3.1%) were Class IV according to Brooker Classification. We found a significant association between admission to an Intensive Care Unit (ICU) (P-value=0.039), chest injury (P-value=0.013), multiple fractures (P-value=0.005), and the time lapse between injury and operation (P-value=0.025), and some statistical significance with surgical approach, ipsilateral fractures, open fractures, tibial and patellar fractures. Age over 30 years as the only prognostic factor for severe HO. Prophylaxis with Indomethacin did not appear to confer any benefit in our patient group.
  
  
  CONCLUSIONS
  The risk factors for developing HO following acetabular fracture fixation are multifactorial and include admission to ICU, associated chest injuries, multiple fractures and delay between injury and surgery. Surgical approach, ipsilateral fractures and tibia and patellar fractures may also play a role. Age over thirty years was the only prognostic factor for developing severe HO.
authors.affiliation: National Centre for Pelvic & Acetabular Surgery, The Adelaide and Meath Hospital, Dublin, Incorporating the National Children's Hospital, Dublin 24, Ireland. Electronic address: yahyaelhassan@gmail.com.
authors.forename: Yahya
authors.initials: Y
authors.lastname: Elhassan
authors.affiliation: National Centre for Pelvic & Acetabular Surgery, The Adelaide and Meath Hospital, Dublin, Incorporating the National Children's Hospital, Dublin 24, Ireland. Electronic address: adyabdelhaq@gmail.com.
authors.forename: Ady
authors.initials: A
authors.lastname: Abdelhaq
authors.affiliation: National Centre for Pelvic & Acetabular Surgery, The Adelaide and Meath Hospital, Dublin, Incorporating the National Children's Hospital, Dublin 24, Ireland. Electronic address: robpiggott1@gmail.com.
authors.forename: Robert P
authors.initials: RP
authors.lastname: Piggott
authors.affiliation: Department of Psychiatry, University College Dublin, Ireland. Electronic address: mugtabasulman@yahoo.co.uk.
authors.forename: Mugtaba
authors.initials: M
authors.lastname: Osman
authors.affiliation: National Centre for Pelvic & Acetabular Surgery, The Adelaide and Meath Hospital, Dublin, Incorporating the National Children's Hospital, Dublin 24, Ireland. Electronic address: johnpmcelwain@eircom.net.
authors.forename: John P
authors.initials: JP
authors.lastname: McElwain
authors.affiliation: National Centre for Pelvic & Acetabular Surgery, The Adelaide and Meath Hospital, Dublin, Incorporating the National Children's Hospital, Dublin 24, Ireland. Electronic address: mleonardorthopaedics@gmail.com.
authors.forename: Mike
authors.initials: M
authors.lastname: Leonard
mesh_terms: D000077:Acetabulum / Q000293:injuries* / Q000601:surgery; D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000627:therapeutic use; D002648:Child; D004008:Diclofenac / Q000627:therapeutic use; D005260:Female; D005500:Follow-Up Studies; D005593:Fracture Fixation, Internal / Q000009:adverse effects / Q000379:methods*; D050723:Fractures, Bone / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D006801:Humans; D015994:Incidence; D007213:Indomethacin / Q000627:therapeutic use; D007494:Ireland / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D009999:Ossification, Heterotopic / Q000175:diagnosis* / Q000188:drug therapy / Q000473:pathology; D011183:Postoperative Complications / Q000175:diagnosis* / Q000188:drug therapy / Q000473:pathology; D011379:Prognosis; D011859:Radiography; D012189:Retrospective Studies; D012307:Risk Factors; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D004008:Diclofenac; D007213:Indomethacin
keywords: Acetabular fractures; Heterotopic Ossification; National Referral Centre