title: Prevalence and risk factors for periprosthetic fracture in older recipients of total hip replacement: a cohort study.
abstract: BACKGROUND
  The growing utilization of total joint replacement will increase the frequency of its complications, including periprosthetic fracture. The prevalence and risk factors of periprosthetic fracture require further study, particularly over the course of long-term follow-up. The objective of this study was to estimate the prevalence and risk factors for periprosthetic fractures occurring in recipients of total hip replacement.
  
  
  METHODS
  We identified Medicare beneficiaries who had elective primary total hip replacement (THR) for non-fracture diagnoses between July 1995 and June 1996. We followed them using Medicare Part A claims data through 2008. We used ICD-9 codes to identify periprosthetic femoral fractures occurring from 2006-2008. We used the incidence density method to calculate the annual incidence of these fractures and Cox proportional hazards models to identify risk factors for periprosthetic fracture. We also calculated the risk of hospitalization over the subsequent year.
  
  
  RESULTS
  Of 58,521 Medicare beneficiaries who had elective primary THR between July 1995 and June 1996, 32,463 (55%) survived until January 2006. Of these, 215 (0.7%) developed a periprosthetic femoral fracture between 2006 and 2008. The annual incidence of periprosthetic fracture among these individuals was 26 per 10,000 person-years. In the Cox model, a greater risk of periprosthetic fracture was associated with having had a total knee replacement (HR 1.82, 95% CI 1.30, 2.55) or a revision total hip replacement (HR1.40, 95% CI 0.95, 2.07) between the primary THR and 2006. Compared to those without fractures, THR recipients who sustained periprosthetic femoral fracture had three-fold higher risk of hospitalization in the subsequent year (89% vs. 27%, p<0.0001).
  
  
  CONCLUSIONS
  A decade after primary THR, periprosthetic fractures occur annually in 26 per 10,000 persons and are especially frequent in those with prior total knee or revision total hip replacements.
authors.affiliation: Orthopedic and Arthritis Center for Outcomes Research, Department of Orthopedic Surgery, Brigham and Women's Hospital, Harvard Medical School, Boston, USA. jnkatz@partners.org.
authors.forename: Jeffrey N
authors.initials: JN
authors.lastname: Katz
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Wright
authors.forename: Julian J Z
authors.initials: JJ
authors.lastname: Polaris
authors.forename: Mitchel B
authors.initials: MB
authors.lastname: Harris
authors.forename: Elena
authors.initials: E
authors.lastname: Losina
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects / Q000639:trends*; D015331:Cohort Studies; D005260:Female; D006760:Hospitalization / Q000639:trends; D006801:Humans; D008297:Male; D016344:Medicare Part A / Q000639:trends*; D057068:Periprosthetic Fractures / Q000175:diagnosis* / Q000453:epidemiology* / Q000209:etiology; D011183:Postoperative Complications / Q000175:diagnosis* / Q000453:epidemiology* / Q000209:etiology; D015995:Prevalence; D012307:Risk Factors; D014481:United States / Q000453:epidemiology