Variability of the lateral femoral cutaneous nerve: An anatomic basis for planning safe surgical approaches

Current surgical assumptions identify the lateral femoral cutaneous nerve (LFCN) running just under the inguinal ligament two fingerbreadths medial to the anterior superior iliac spine (ASIS). On the basis of the increasing incidence of Meralgia Paresthetica associated with various surgical procedures, it is clear that surgeons are relying on an inadequate description of the nerve's course. This study provides a better understanding of the variability of the LFCN with regards to its relationship to the ASIS and the depth at which it passes deep to the inguinal ligament. A total of 35 bodies were examined yielding 65 sets of data. Dissections were performed on 26 formalin fixed cadavers and 9 fresh morgue specimens. Measurements and calculations were made with regard to the distance from the LFCN to the ASIS along the inguinal ligament, the depth of the LFCN as it crossed the inguinal ligament, and the length of the inguinal ligament. The LFCN was observed to cross the inguinal ligament 1.4 +/- 0.4 cm medial to the ASIS with a standard deviation of 1.5 cm. The LFCN traversed the inguinal ligament 1.0 +/- 0.1 cm deep to the ligament with a standard deviation of 0.6 cm. The LFCN runs approximately one fingerbreadth medial to the ASIS. The nerve may be found far more medial or lateral than expected with several distinct branching patterns. In addition, the LFCN crosses deeper to the inguinal ligament than previously described in the literature, with a high variability of depth between specimens.