title: Uni- and bipolar hemiarthroplasty with a modern cemented femoral component provides elderly patients with displaced femoral neck fractures with equal functional outcome and survivorship at medium-term follow-up.
abstract: BACKGROUND
  The choice between unipolar and bipolar hemiarthroplasty for treatment of displaced intracapsular femoral neck fractures in elderly patients still remains controversial. Our objective was to compare series of elderly individuals with a displaced femoral neck fracture treated with either a cemented, modular unipolar or bipolar prosthesis with the same femoral component.
  
  
  METHODS
  A prospective, randomized controlled trial of 175 displaced intracapsular femoral neck fractures in patients over 65 years was randomly allocated to unipolar (88) and to bipolar (87) hemiarthroplasty group. The primary end point was implant survival. Secondary end points included difference in ambulatory ability and mortality. Follow-up evaluations were performed at 2 months, at 1, 3 and 5 years. Implant and patient survival were followed until 2/2012. Survival analyses were performed using Kaplan-Meier curves with log-rank test. Data were analyzed using Chi-square test and Student's t test.
  
  
  RESULTS
  Unipolar hemiarthroplasty group had a significantly higher dislocation rate when compared with bipolar hemiarthroplasty group. This did not translate into difference in revision rates at 8 years. Prosthetic survival ship was 0.98 (95% Cl 0.94-1.00) in the unipolar group and 0.97 (95% Cl 0.93-1.00) in the bipolar group. There were no statistically significant differences in ambulatory ability, possibility to return home mortality or early radiological acetabular erosion. There were significantly more one-time dislocations in the unipolar group, but there was no difference in incidence of revisions due to recurrent dislocations. The overall mortality rate was 6% at 30 days, 9% at 90 days, 16% at 12 months, and 53% at 5 years. There was no difference in mortality between the groups.
  
  
  CONCLUSIONS
  Unipolar hemiarthroplasty group had a significantly higher dislocation rate when compared with bipolar hemiarthroplasty group. However, both provide elderly patients with equal ambulatory ability and low revision rate at medium-term follow-up.
authors: Department of Orthopedics, Hatanpää Hospital, Hatanpäänkatu 24, P.O.Box 487, 33101, Tampere, Finland.
authors: Kari
authors: K
authors: Kanto
authors: Raine
authors: R
authors: Sihvonen
authors: Antti
authors: A
authors: Eskelinen
authors: Minna
authors: M
authors: Laitinen
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000295:instrumentation / Q000379:methods*; D005260:Female; D005265:Femoral Neck Fractures / Q000601:surgery*; D005500:Follow-Up Studies; D062785:Hemiarthroplasty / Q000295:instrumentation / Q000379:methods*; D006617:Hip Dislocation / Q000453:epidemiology / Q000209:etiology; D006622:Hip Prosthesis; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D011183:Postoperative Complications / Q000453:epidemiology; D011446:Prospective Studies; D011475:Prosthesis Failure; D012086:Reoperation / Q000706:statistics & numerical data; D016896:Treatment Outcome