Localizing the Sciatic Nerve in the Gluteal Region Using Surface Projections: A Cadaveric Study

Localization of the sciatic nerve (SN) for pain management commonly relies on ultrasound (US), but that resource may not be available in some rural health clinics and impoverished countries. The purpose of this study is to investigate the use of surface projections within the gluteal region (GR), which are the greater trochanter (GT), ischial tuberosity (IT), and the apex of the sacral hiatus (ASH), to localize the SN and assess sex differences of the SN in orientation to those landmarks. We hypothesize that if the GT, IT, and ASH are reliable in localizing the SN, then we will be able to localize the SN with a reliability greater than or equal to 80%. Using 14 embalmed, OMS-I dissected cadaveric specimens (seven males, seven females), nine different measurements were taken using a digital caliper to establish the orientation of the SN to the GT, IT, and ASH within the GR. Using this data, two reference points (one superior: one inferior) for the SN were identified on the left and right GR of 10 fresh frozen cadavers (five males, five females). Pink latex was injected at the superior point; blue latex at the inferior point, followed by a simple gluteus maximus muscle dissection to verify the location of the latex to the SN. A Welch's t-test was used to analyze any sex differences between the left and right GR, and a Student t-test was used to compare the left and right GR within each sex. There was no significant difference between the nine measurements found within each sex; however, between each sex, there were several measurements that displayed significant differences. Latex injected into the superior point proved better for localizing the SN without using US. Although there were significant differences in the SN measurements between the sexes, the study showed that these three bony landmarks could locate the sciatic nerve accurately. This method could provide clinicians who lack the resources of US or other imaging modalities to localize the SN reliably.