Piriformis muscle rupture during total hip arthroplasty using a muscle-preserving posterior approach.

Total hip arthroplasty via muscle-sparing approaches is advocated and performed with increasing frequency. However, performing total hip arthroplasty through muscle-sparing approaches may require a more forceful retraction, which in turn may damage the muscles which the less invasive approach intended to preserve. We report on the rupture of the piriformis muscle during primary total hip replacement performed through a posterior approach intended to preserve this muscle. The prevalence and effects of such iatrogenic injuries are currently unknown, although unrecognised muscle damage may be a potential reason why early postoperative gait analyses could not demonstrate the expected benefits of less invasive surgery. Surgeons should be aware of this potential complication when performing total hip arthroplasty through a less invasive posterior approach.