title: Unipolar hemiarthroplasty versus bipolar hemiarthroplasty in patients with displaced femoral neck fractures: a four-year follow-up of a randomised controlled trial.
abstract: OBJECTIVE
  The treatment of choice for a displaced femoral neck fracture in the most elderly patients is a cemented hemiarthroplasty (HA). The optimal design, unipolar or bipolar head, remains unclear. The possible advantages of a bipolar HA are a better range of motion and less acetabular wear. The aim of this study was to evaluate hip function, health related quality of life (HRQoL), surgical outcome and acetabular erosion in a medium-term follow-up.
  
  
  METHODS
  One hundred and twenty patients aged 80 or more with a displaced fracture of the femoral neck (Garden III and IV) were randomised to treatment with a cemented Exeter HA using a unipolar or a bipolar head. All patients were able to walk independently, with or without aids, before surgery. Follow-ups were performed at four, 12, 24 and 48 months postoperatively. Assessments included HRQoL (EQ-5D index score), hip function (Harris hip score [HHS]) and radiological acetabular erosion.
  
  
  RESULTS
  The mean EQ-5D index score was generally higher among the patients with bipolar hemiarthroplasties at the follow-ups with a significant difference at 48 months: unipolar HAs 0.59 and bipolar HAs 0.70 (p = 0.04). There was an increased rate of acetabular erosion among the patients with unipolar hemiarthroplasties at the early follow-ups with a significant difference at 12 months (unipolar HAs 20% and bipolar HAs 5%, p = 0.03). At the later follow-ups the incidence of acetabular erosion accelerated in the bipolar group, and there were no significant differences between the groups at the 24- and 48-month follow-ups. There was no difference in HHS or reoperation rate between the groups at any of the follow-ups.
  
  
  CONCLUSIONS
  The bipolar HAs seem to result in better HRQoL beyond the first two years after surgery compared to unipolar HAs. Bipolar HAs displayed a later onset of acetabular erosion compared to unipolar HAs.
authors.forename: Christian
authors.initials: C
authors.lastname: Inngul
authors.forename: Carl-Johan
authors.initials: CJ
authors.lastname: Hedbeck
authors.forename: Richard
authors.initials: R
authors.lastname: Blomfeldt
authors.forename: Gunilla
authors.initials: G
authors.lastname: Lapidus
authors.forename: Sari
authors.initials: S
authors.lastname: Ponzer
authors.forename: Anders
authors.initials: A
authors.lastname: Enocson
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005265:Femoral Neck Fractures / Q000601:surgery*; D005272:Femur Neck / Q000601:surgery; D005500:Follow-Up Studies; D062785:Hemiarthroplasty / Q000145:classification* / Q000379:methods*; D006621:Hip Joint / Q000502:physiology; D006622:Hip Prosthesis; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D011446:Prospective Studies; D011788:Quality of Life; D016059:Range of Motion, Articular / Q000502:physiology; D013997:Time Factors; D016896:Treatment Outcome