In 465 patients treated surgically for low back and lower extremity disability, almost 10 per cent had femoral rather than sciatic distribution of pain. The average age of patients who had a primarily femoral distribution of pain is higher by a decade than those who had a predominantly sciatic distribution of pain; the higher level of the lesion and greater incidence of apophyseal joint arthritis may be associated with the aging process. The femoral distribution of pain may lead to difficulties in differential diagnosis between a spinal origin and a hip or knee origin of the problem. Radiculopathy causing femoral pain may be the result of both disk degeneration with protrusion and apophyseal arthritis with synovitis. Neuritis of the L4 nerve root is more commonly the result of a lesion at the L4-5 nerve root foramen than centrally at the L3-4 disk level. The syndrome of low back pain with femoral neuritis is not uncommon 5 or more years after an otherwise successful L4-S1, two level spine fusion. This syndrome can result from an L3-4 disk protrusion with nerve root neuritis but may be a reflex disturbance from the posterior arch structures as evidenced by fusion mass, apophyseal joint or spinous process overgrowth and associated soft tissue inflammation.
