Obturator Nerve Entrapment

Introduction

  • This neve can become entrapped secondary to trauma such as a pelvic fracture, post-surgical fibrosis (Cardosi et al 2002), hip arthroplasty, or from overuse
  • Traumatic entrapment occurs around the course of the nerve close to the pelvic ring (Barrick 1998) and acetabulum (Yang 2001) after a fracture
  • Overuse entrapment occurs secondary to vascular changes under the deep fascia found posterior to the adductor longus and pectineus (Harvey et al 1999)
  • The obturator nerve arises from the anterior division of the 2nd, 3rd and 4th lumbar ventral rami in the dorsal portion of the psoas muscle. It emerges medially at the sacral ala and travels along the ilio-pectineal line into the lesser pelvis, with a close relation to the anterior medial wall of the acetabulum. It leaves the pelvis through the anterolateral portion of the obturator foramen and provides motor function to adductor muscles of the thigh and gives sensory innervation to an area on the medial surface of the lower thigh (Heimer 1995).

Clinical Presentation and Diagnosis

  • Pain radiating from the groin into the medial upper aspect of the thigh
  • Patients may complain of adductor weakness and medial thigh paresthesias after exercise (Bradshaw et al 1997) or in severe cases (Sorenson 2002)
  • Diagnosis can be made through electromyogram and diagnostic block (Bradshaw et al 1997)

Treatment

  • Treatment of choice is surgical neurolysis (Bradshaw et al 1997)
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