Tibial nerve dysfunction is a loss of movement or sensation in the lower leg, caused by damage to the tibial nerve.

Tibial nerve dysfunction is a form of peripheral neuropathy. It occurs when there is damage to the tibial nerve, one of the branches of the sciatic nerve of the leg. The tibial nerve supplies movement and sensation to the calf and foot muscles.

Dysfunction of a single nerve group, such as the tibial nerve, is called mononeuropathy. Mononeuropathy implies a local cause of the nerve damage, although occasionally systemic disorders may cause isolated nerve damage (such as occurs with mononeuritis multiplex).

The usual causes are direct trauma, prolonged pressure on the nerve, and compression of the nerve from nearby body structures. Entrapment involves pressure on the nerve where it passes through a narrow structure.

The damage may include destruction of the myelin sheath of the nerve (the insulation around the nerve) or destruction of part of the nerve cell (the axon). Damage to either part slows or prevents conduction of impulses through the nerve.

The tibial nerve is commonly injured by fractures or other injury to the back of the knee or the lower leg. It may be affected by systemic diseases causing polyneuropathy (damage to multiple nerves) such as diabetes. It may be damaged by pressure from lesions such as tumor, abscess, or bleeding into the knee.

In some cases, no cause can be identified.