Moderate evidence supports that the outcomes of unipolar and bipolar hemiarthroplasty for unstable (displaced) femoral neck fractures are similar.

Management of Hip Fractures in the Elderly
Endorsed by: OTA, AGS, AAPM&R, ASBMR, USBJI, The Hip Society, AACE, ORA
Moderate Evidence MODERATE EVIDENCE
Rationale
One high strength study (Davison et al 49) and seven moderate strength (Raia et al 74, Cornell et al 75, Jeffcote et al 76, Calder et al 60, Calder et al 77, Hedbeck et al 78, Kenzora et al 79) Kenzora studies compared unipolar and bipolar hemiarthroplasty for the treatment of displaced femoral neck fractures.  All of the included studies showed equivalence in functional and radiographic outcomes, suggesting no significant benefit for bipolar articulation over unipolar hemiarthroplasty for displaced femoral neck fracture. A meta-analysis of mortality at six months and one year show no significant differences between unipolar and bipolar hemiarthroplasty.
 
Risks and Harms of Implementing this Recommendation
The majority of the reviewed studies reported that that unipolar heads were acknowledged as being significantly less expensive than the bipolar heads without any accompanying clinical difference recognized. 
There is no apparent harm associated with implementing this recommendation and cost savings represent a direct economic benefit from the preferential use of unipolar articulations.

Future Research
None needed

 
  1. (49) Davison JN, Calder SJ, Anderson GH et al. Treatment for displaced intracapsular fracture of the proximal femur. A prospective, randomised trial in patients aged 65 to 79 years. The Journal of bone and joint surgery British volume 2001;83):206-212.
  2. (60) Calder SJ, Anderson GH, Harper WM, Jagger C, Gregg PJ. A subjective health indicator for follow-up. A randomised trial after treatment of displaced intracapsular hip fractures. J Bone Joint Surg Br 1995;77(3):494-496.
  3. (74) Raia FJ, Chapman CB, Herrera MF, Schweppe MW, Michelsen CB, Rosenwasser MP. Unipolar or bipolar hemiarthroplasty for femoral neck fractures in the elderly? Clin Orthop Relat Res 2003;(414):259-265.
  4. (75) Cornell CN, Levine D, O'Doherty J, Lyden J. Unipolar versus bipolar hemiarthroplasty for the treatment of femoral neck fractures in the elderly. Clin Orthop Relat Res 1998;(348):67-71.
  5. (76) Jeffcote B, Li MG, Barnet-Moorcroft A, Wood D, Nivbrant B. Roentgen stereophotogrammetric analysis and clinical assessment of unipolar versus bipolar hemiarthroplasty for subcapital femur fracture: a randomized prospective study. ANZ J Surg 2010;80(4):242-246.
  6. (77) Calder SJ, Anderson GH, Jagger C, Harper WM, Gregg PJ. Unipolar or bipolar prosthesis for displaced intracapsular hip fracture in octogenarians: a randomised prospective study. J Bone Joint Surg Br 1996;78(3):391-394.
  7. (78) Hedbeck CJ, Blomfeldt R, Lapidus G, Tornkvist H, Ponzer S, Tidermark J. Unipolar hemiarthroplasty versus bipolar hemiarthroplasty in the most elderly patients with displaced femoral neck fractures: a randomised, controlled trial. Int Orthop 2011.
  8. (79) Kenzora JE, Magaziner J, Hudson J et al. Outcome after hemiarthroplasty for femoral neck fractures in the elderly. Clin Orthop Relat Res 1998;(348):51-58.