Posterior Approach and Dislocation Rate: A 213 Total Hip Replacements Case-Control Study Comparing the Dual Mobility Cup With a Conventional 28-mm Metal head/polyethylene Prosthesis

Orthop Traumatol Surg Res. 2011 Feb;97(1):2-7. doi: 10.1016/j.otsr.2010.07.008. Epub 2010 Dec 21.


Introduction: Dislocation is a frequent complication of total hip arthroplasties (THA) especially in older patients, especially when using a posterior approach. In these cases, dual mobility (DM) cups developed by Gilles Bousquet in 1975 can be indicated to reduce this complication risk.

Hypothesis: Dual mobility cups reduce the rate of dislocation in primary total hip arthroplasty using posterior approach in a single-surgeon series.

Aim: Test this hypothesis in a controlled study to compare the rate of dislocation in primary total hip arthroplasties done in patients over 50 years old either with a dual mobility cup or a conventional metal-on-polyethylene 28-mm diameter head.

Patients and methods: Two consecutive series of primary total hip replacements were performed by a single surgeon using a posterolateral approach. The piriformis tendon was left intact. The DM series included 105 patients who underwent arthroplasty between January 2005 and June 2007 with a dual mobility cup (60 women and 45 men, mean age 76.6±5.65 years old [53-93]). The control series (S series) included 108 patients who underwent arthroplasty (56 women and 52 men, mean age 74.2±5.9 years old [53-87]) with a conventional 28-mm polyethylene cup between January 2003 and June 2005. All hip replacements included a 28-mm metal-polyethylene cup and a 12-14-mm Morse taper. Both groups were comparable for gender, diagnosis, body mass index, type of anesthesia and ASA score distribution. All patients included in this series had a minimum follow-up of 1 year.

Results: There were no dislocations in the DM series and five early dislocations (before the third month) in the S series for a rate of 4.63%. Although the rate of dislocation was higher in the S series (4.63% vs 0%), the difference was barely significant (P=0.0597).

Discussion: This study comparing the incidence of dislocations after THA with conventional or dual mobility cups, shows that even using a posterior approach and in older patients, dual mobility cups increase stability with no postoperative dislocations. Although results are barely significant, a larger series should confirm the benefit of this implant. In this series, morbidity was not increased with dual mobility cups.

Level of evidence: Level III: retrospective case-control study.

Publication types

  • Comparative Study

MeSH terms

  • Aged
  • Aged, 80 and over
  • Arthroplasty, Replacement, Hip / adverse effects*
  • Female
  • Follow-Up Studies
  • Hip Dislocation / etiology*
  • Hip Prosthesis / adverse effects*
  • Humans
  • Male
  • Middle Aged
  • Osteoarthritis, Hip / surgery*
  • Polyethylenes*
  • Postoperative Complications
  • Prosthesis Design
  • Prosthesis Failure
  • Retrospective Studies
  • Time Factors


  • Polyethylenes