Objectives. 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. . Conclusion. 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
