Relief of Sitting Pain by Resecting the Posterior Femoral Cutaneous Nerve, and Elucidation of its Anatomical Branching Pattern
Bart Kachniarz, MD, MBA, Johns Hopkins University, Baltimore, MD, A. Lee Dellon, MD, PhD, Plastic Surgery, Johns Hopkins University, Baltimore, MD; Plastic Surgery, Dellon Institute for Peripheral Nerve Surgery, Towson, MD and Eric H Williams, MD, Dellon Institute for Peripheral Nerve Surgery, Towson, MD
Sitting pain has been ascribed to pudendal nerve compression at the sacrotuberous ligament. However, when sitting produces pain in the buttock and posterior thigh as well as the ischial tuberosity, the posterior femoral cutaneous nerve (PFCN) must be the peripheral nerve to evaluate and treat, as pudendal nerve compression causes pain in the rectum, vagina/perineum/scrotum, and the clitoris/penis. The anatomy of the PFCN has not been well described, and just one small cohort of 17 patients has been reported to have surgery for the PFCN.
METHODS & MATERIALS:
A cohort of patients with sitting pain was included by these criteria: 1) disabling sitting pain referred to skin territory of the PFCN, 2) relief of that pain with nerve block of the PFCN. Exclusion criteria included previous buttock surgery; previous pudendal nerve surgery was not cause for exclusion.
Fifty-two patients were included in this study. Presence of MRI evidence of hamstring injury was present in 48% of patients. Evaluation was done by chart review, intra-operative description of the anatomy of the PFCN, and the outcome of resection of the PFCN with implantation of the proximal nerve into the gluteus muscle.
Outcomes were determined by direct patient examination, email reports, and telephonic interviews. Operative reports were available for 51 patients, of which 9 underwent bilateral procedures. Thirty-four patients had sufficient follow-up data to assess post-operative outcomes at a mean of 25.6 months (6.2 to 84.7 months, range).
The classic PFCN anatomy was present in 43% of patients with the other 57% having a high division permitting branches to the lateral buttock (inferior cluneal nerve) and posterior thigh to be preserved. In patients with bilateral anatomy observations, symmetry was present in 78%.
An excellent result (absence of sitting pain, normal activities of daily living [ADL]) was obtained in 52.9%, a good result (some residual sitting pain with some reduction in ADL) was obtained in 29.4%, and no improvement was observed in 17.6% of patients.
Sitting pain due to injury to the PFCN can be relieved by resection of the PFCN with implantation of the proximal end into the gluteus muscle. Presence of an anatomic variation, a high division of the PFCN, can permit preservation of sensation in the lateral buttock and posterior thigh.
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