A comparison of a less invasive piriformis-sparing approach versus the standard posterior approach to the hip: A randomised controlled trial

J Bone Joint Surg Br. 2012 Jan;94(1):43-50. doi: 10.1302/0301-620X.94B1.27001.


We undertook a randomised controlled trial to compare the piriformis-sparing approach with the standard posterior approach used for total hip replacement (THR). We recruited 100 patients awaiting THR and randomly allocated them to either the piriformis-sparing approach or the standard posterior approach. Pre- and post-operative care programmes and rehabilitation regimes were identical for both groups. Observers were blinded to the allocation throughout; patients were blinded until the two-week assessment. Follow-up was at six weeks, three months, one year and two years. In all 11 patients died or were lost to follow-up. There was no significant difference between groups for any of the functional outcomes. However, for patients in the piriformis-sparing group there was a trend towards a better six-minute walk test at two weeks and greater patient satisfaction at six weeks. The acetabular components were less anteverted (p = 0.005) and had a lower mean inclination angle (p = 0.02) in the piriformis-sparing group. However, in both groups the mean component positions were within Lewinnek's safe zone. Surgeons perceived the piriformis-sparing approach to be significantly more difficult than the standard approach (p = 0.03), particularly in obese patients. In conclusion, performing THR through a shorter incision involving sparing piriformis is more difficult and only provides short-term benefits compared with the standard posterior approach.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Aged
  • Aged, 80 and over
  • Arthroplasty, Replacement, Hip / adverse effects
  • Arthroplasty, Replacement, Hip / methods*
  • Arthroplasty, Replacement, Hip / rehabilitation
  • Epidemiologic Methods
  • Exercise Test
  • Female
  • Humans
  • Male
  • Middle Aged
  • Minimally Invasive Surgical Procedures / adverse effects
  • Minimally Invasive Surgical Procedures / methods
  • Minimally Invasive Surgical Procedures / rehabilitation
  • Osteoarthritis, Hip / surgery*
  • Pain, Postoperative / etiology
  • Patient Satisfaction
  • Treatment Outcome
  • Walking