Severe femoral neuropathy with "hanging leg" syndrome.

Severe femoral neuropathy with a partial sciatic nerve injury is an unusual clinical finding in the absence of penetrating trauma, pelvic fracture, hemorrhage, mass lesion, or peripheral neuropathy. This report documents the occurrence of this condition and discusses its recognition despite lack of detectable radiologic or routine laboratory abnormalities. A careful history and clinical electrodiagnosis are the most important factors in establishing the nature of the mechanism of injury, anatomic location, diagnosis, and prognosis. Review of these factors suggests that the injury is related to nerve stretching or compression with prolonged maintenance of a "hanging leg" position on the affected side.