Poster 198: Risk of Injury During Proximal Hamstring Repair: Anatomy of the Posterior Femoral Cutaneous Nerve

OBJECTIVES: Injury to the posterior femoral cutaneous nerve (PFCN) has been described after proximal hamstring repair and fixation of ischial tuberosity avulsion fractures. Variations in the location of the PFCN and its branches have not been described. The purpose of this study was to identify the location and number of branches of the PFCN in relation to the origin of the proximal hamstring tendons. METHODS: Fifteen lower torso human cadaveric specimens were dissected in prone position. Skin and subcutaneous tissues were reflected to expose the gluteal and hamstring musculature. The distances between the ischial tuberosity and lateral border of the hamstring, PFCN, perineal branch of the PFCN, and descending femoral branch of the PFCN were measured with digital calipers. Measurements were repeated 3 times and averaged. RESULTS: The PFCN was 30.5 ±11.4 mm lateral to the central tip of the ischial tuberosity (range, 15.7 to 52.0 mm). The average longitudinal distance from the tip of the ischial tuberosity to the point where the perineal branch crossed the hamstrings was 24.1 ±15.0 mm (range, 9.9 to 52.2 mm). The average longitudinal distance to the point where the descending cutaneous branch crossed the hamstrings was 83.3 ±21.3 mm (range, 41.3 to 110.3 mm). The PFCN was nearest to the inferior border of the gluteus maximus 45.8±13.6 mm lateral to the ischial tuberosity (range, 13.6 to 62.1 mm). Eleven specimens had one identifiable perineal branch; four had two distinct perineal branches. CONCLUSIONS: The PFCN was in close proximity to the surgical approach utilized during proximal hamstring repair, with the perineal branch consistently crossing the surgical field transversely. The location of these nerves varied substantially among the specimens tested, with some nerves positioned less than 1cm from the ischial tuberosity and some specimens having two perineal branches.