THE ANATOMICAL RELATIONS OF THE SUPERIOR GLUTEAL NERVE AND DAMAGE TO IT DURING THE DIRECT LATERAL APPROACH TO THE HIP – A CADAVERIC STUDY

Abstract

We examined the position of the superior gluteal nerve in forty-four cadaveric hips in relation to the greater trochanter and the acetabulum . We found that the nerve lay a mean of 4.8 centimetres from the greater trochanter with a range of two to nine centimetres and a mean of 3.2 centimetres from the acetabulum. The nerve was visibly damaged in three out of forty-four hips following direct lateral approach. Our study does not support the “safe zone” proximal to the greater trochanter and suggests the proximity of the nerve to the acetabulum as a potential cause of nerve injury.

Abductor weakness following the direct lateral approach to the hip is well described and is associated with damage to the superior gluteal nerve on neurophysiological testing in from 23–26 %. A “safe zone” has been described of up to five centimeters proximal to the greater trochanter.

We examined forty-four cadaveric hips exposed by the direct lateral approach by surgeons not directly involved with the study. We measured the position of the superior gluteal nerve in relation to the greater trochanter, the acetabulum and the margin of the skin incision. We examined the nerve for visible signs of damage.

We found the position of the superior gluteal nerve to be a mean of 4.8 centimeters from the greater trochanter (range two to nine), 3.2 centimeters from the superior margin of the acetabulum (range one to eight), and 4.1 centimeters from the margin of the skin incision. There was visible damage to the nerve in three of forty-four cases.

Neurophysiological studies show subclinical damage to the superior gluteal nerve in up to 77% of cases following direct lateral approach to the hip and in association with abductor weakness in 23–26%. Our study does not support the notion of a “safe zone” of five centimetres proximal to the greater trochanter, and with a mean of 4.8 centimetres the zone is unsafe more often than it is safe. The proximity of the superior gluteal nerve to the superior margin of the acetabulum suggests that it may be damaged by retractor placement at this site.