title: The role of retraction in direct nerve injury in total hip replacement: an anatomical study.
abstract: OBJECTIVE
  Acetabular retractors have been implicated in damage to the femoral and obturator nerves during total hip replacement. The aim of this study was to determine the anatomical relationship between retractor placement and these nerves.
  
  
  METHODS
  A posterior approach to the hip was carried out in six fresh cadaveric half pelves. Large Hohmann acetabular retractors were placed anteriorly, over the acetabular lip, and inferiorly, and their relationship to the femoral and obturator nerves was examined.
  
  
  RESULTS
  If contact with bone was not maintained during retractor placement, the tip of the anterior retractor had the potential to compress the femoral nerve by passing superficial to the iliopsoas. If pressure was removed from the anterior retractor, the tip pivoted on the anterior acetabular lip, and passed superficial to the iliopsoas, overlying and compressing the femoral nerve, when pressure was reapplied. The inferior retractor pierced the obturator membrane in all specimens medial to the obturator nerve, with subsequent retraction causing the tip to move laterally, making contact with the nerve.
  
  
  CONCLUSIONS
  Iliopsoas can only offer protection to the femoral nerve if the retractor passes deep to the muscle bulk. The anterior retractor should be reinserted if pressure is removed intra-operatively. Vigorous movement of the inferior retractor should be avoided. Cite this article: Bone Joint Res 2014;3:212-6.
authors: University of Glasgow, Laboratory of Human Anatomy, University of Glasgow, Glasgow, G12 8QQ, UK.
authors: F A
authors: FA
authors: McConaghie
authors: University of Glasgow, Laboratory of Human Anatomy, University of Glasgow, Glasgow, G12 8QQ, UK.
authors: A P
authors: AP
authors: Payne
authors: Golden Jubilee National Hospital, Department of Orthopaedics, Agamemnon Street, Clydebank, G81 4DY, UK.
authors: A W G
authors: AW
authors: Kinninmonth
keywords: Hip Replacement; Nerve Injury; Retractors