ePoster #308 - ISHA Annual Scientific Meeting 2016

Anatomical Description of a Sciatic Ancillary Branch to the Gluteus Maximus

Salvador Campos Dorador, MD, Guadalajara, Jalisco MEXICO
Ricardo Goncalves Schroder, PT, Dallas, TX UNITED STATES
Anthony Khoury, MSc, Dallas, TX UNITED STATES
Ian James Palmer, PhD, Oklahoma City, OK UNITED STATES
Hal David Martin, DO, Dallas, TX UNITED STATES

Hip Preservation Center Hip Preservation Center at Baylor Scott&Withe Health System, Dallas, Texas, UNITED STATES

FDA Status Not Applicable

Summary: Previous anatomical descriptions have shown that the inferior gluteal nerve innervates the Gluteus maximus muscle. The objective of this study was to examine the potential presence of the Sciatic Ancillary Branch to Gluteus Maximus (SAB), an ancillary branch from the Sciatic Nerve (SN) to the gluteus maximus separated to the inferior gluteal nerve.

Abstract:
Introduction
Previous anatomical descriptions have shown that the inferior gluteal nerve innervates the Gluteus maximus muscle. The objective of this study was to examine the potential presence of the Sciatic Ancillary Branch to Gluteus Maximus (SAB), an ancillary branch from the Sciatic Nerve (SN) to the gluteus maximus separated to the inferior gluteal nerve. In the cases with a confirmed branch, measurements of width and length were taken.

Methods
Thirteen hips from seven fresh frozen human cadaveric pelvises were analyzed. Specimens were placed on a surgical table in prone position with lower extremities in neutral position. A Posterolateral approach was made reflecting the gluteus maximus to expose the deep gluteal space. Two investigators independently observed the deep gluteal space and indicated the presence or absence of the SAB. If present, a digital caliper was utilized to perform the following measurements: (I) diameter of the sciatic nerve, and SAB (II) at the origin point of the SAB at the sciatic nerve; (III) the distance between the grater sciatic foramen and the origin point of the SAB; (IV) SAB length from sciatic nerve to the initial point of contact in the gluteus maximus.

Results
Of 13 hips, five (38%) showed the presence of SAB. (I) The mean diameter of the sciatic nerve was 13.61 mm ± 3.69, (II) the mean diameter of the SAB in the origin at the sciatic nerve was 2.45 mm ± 1.20, (III) the mean distance from the grater sciatic foramen at the point of origin of the SABGM in the sciatic nerve was 15.80 mm ± 11.73, (IV) the mean length of SAB from sciatic nerve to the point of contact to gluteus maximus was 15.75 mm. ± 10.44.

Conclusion
The SABGM was observed in 38% of the analyzed hips. This is the first description of a direct branch from the sciatic nerve innervating the gluteus maximus. The present findings offer a better understanding of the anatomical variations into the deep gluteal space and may help to guide treatment decisions and outcomes.