title: High risk of early periprosthetic fractures after primary hip arthroplasty in elderly patients using a cemented, tapered, polished stem.
abstract: OBJECTIVE
  Postoperative periprosthetic femoral fracture (PPF) after hip arthroplasty is associated with considerable morbidity and mortality. We assessed the incidence and characteristics of periprosthetic fractures in a consecutive cohort of elderly patients treated with a cemented, collarless, polished and tapered femoral stem (CPT).
  
  
  METHODS
  In this single-center prospective cohort study, we included 1,403 hips in 1,357 patients (mean age 82 (range 52-102) years, 72% women) with primary osteoarthritis (OA) or a femoral neck fracture (FNF) as indication for surgery (367 hips and 1,036 hips, respectively). 64% of patients were ASA class 3 or 4. Hip-related complications and need for repeat surgery were assessed at a mean follow-up time of 4 (1-7) years. A Cox regression analysis was used to evaluate risk factors associated with PPF.
  
  
  RESULTS
  47 hips (3.3%) sustained a periprosthetic fracture at median 7 (2-79) months postoperatively; 41 were comminute Vancouver B2 or complex C-type fractures. The fracture rate was 3.8% for FNF patients and 2.2% for OA patients (hazard ratio (HR) = 4; 95% CI: 1.3-12). Patients > 80 years of age also had a higher risk of fracture (HR = 2; 95% CI: 1.1-4.5).
  
  
  CONCLUSIONS
  We found a high incidence of early PPF associated with the CPT stem in this old and frail patient group. A possible explanation may be that the polished tapered stem acts as a wedge, splitting the femur after a direct hip contusion. Our results should be confirmed in larger, registry-based studies, but we advise caution when using this stem for this particular patient group.
authors.affiliation: Department of Orthopedics at Danderyd Hospital and Department of Clinical Sciences at Danderyd Hospital (KIDS) , Karolinska Institutet , Stockholm.
authors.forename: Cyrus
authors.initials: C
authors.lastname: Brodén
authors.forename: Sebastian
authors.initials: S
authors.lastname: Mukka
authors.forename: Olle
authors.initials: O
authors.lastname: Muren
authors.forename: Thomas
authors.initials: T
authors.lastname: Eisler
authors.forename: Henrik
authors.initials: H
authors.lastname: Boden
authors.forename: André
authors.initials: A
authors.lastname: Stark
authors.forename: Olof
authors.initials: O
authors.lastname: Sköldenberg
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000379:methods*; D015331:Cohort Studies; D005260:Female; D005265:Femoral Neck Fractures / Q000601:surgery*; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000601:surgery*; D057068:Periprosthetic Fractures / Q000453:epidemiology*; D011183:Postoperative Complications / Q000453:epidemiology*; D016016:Proportional Hazards Models; D011446:Prospective Studies; D011474:Prosthesis Design; D012306:Risk