Femoral nerve injuries - Disorders of Peripheral nerves

Femoral nerve injuries

Definition

The femoral nerve is a branch of the lumbar plexus, from nerve roots L1–4, and it supplies flexors of the hip and extensors of the knee.

Aetiology/pathophysiology

Complete division of the femoral nerve is rare. It may be injured by a gunshot wound, traction in an operation or bleeding into the thigh.

In the abdomen, the femoral nerve is related to the psoas muscle and supplies iliopsoas. It enters the thigh lateral to the femoral to supply the hamstring muscles in the thigh. Its two divisions, then supply all the anterior compartment muscles of the thigh, namely quadriceps femoris, which is a powerful extensor of the knee, and the skin of the medial and anterior surfaces of the thigh.

Clinical features

Weakness of knee extension and numbness of the medial and anterior aspect of the thigh, the medial aspect of the lower leg and the medial border of the foot. The knee jerk is depressed or absent. Hip flexion is only slightly affected and adduction is preserved.

Management

Evacuation of a haematoma or direct suturing or grafting of a cut nerve.

Prognosis

This is a disabling injury. In walking, quadriceps weak-ness can be compensated for to some extent by the adductor muscles.