Definition of Femoral nerve dysfunction:

Femoral nerve dysfunction is a loss of movement or sensation in the leg due to nerve damage.

See also: Peripheral neuropathy; Mononeuropathy; Mononeuritis multiplex

Causes, incidence, and risk factors:

The femoral nerve is located in the leg. It supplies the muscles that help straighten the leg. It provides feeling (sensation) to the front of the thigh and part of the lower leg.

A nerve is made up of many fibers, called axons, surrounded by insulation, called the myelin sheath.

Damage to a nerve such as the femoral nerve is called mononeuropathy. Mononeuropathy usually means there is a local cause of the nerve damage, although disorders that involve the entire body (systemic disorders) can also cause isolated nerve damage (such as occurs with mononeuritis multiplex).

The usual causes of femoral nerve dysfunction are direct injury (trauma), prolonged pressure on the nerve, and compression of the nerve by nearby parts of the body or disease-related structures (such as a tumor). Prolonged pressure may lead to a lack of oxygen because there is decreased blood flow (ischemia) in the area. This lack of oxygen can cause further complications.

Entrapment involves pressure on the nerve where it passes through a narrow structure (for example, as it passes through a muscle). The damage includes destruction of the insulation around the nerve (the myelin sheath) or destruction of part of the fibers themselves (the axon). This damage slows or prevents nerve impulses from passing through the nerve.

The femoral nerve can be injured due to breaking bones of the pelvis. It can be injured when a catheter is placed in the artery in the groin (femoral artery), which lies next to the nerve. It can be one of many nerves affected by diseases causing widespread nerve damage (polyneuropathy), such as diabetes. It also can be damaged by pressure from tumors, abscesses, or internal bleeding into the pelvis or abdomen.

One common risk factor is lying on the back with the thighs and legs flexed ("lithotomy" position) during surgery or diagnostic procedures. Branches of the femoral nerve can be compressed by tight or heavy waist belts. In some cases, no cause can be found.