Tibial Nerve Block at the Knee

Indications and Clinical Considerations

Tibial nerve block at the knee is useful in evaluating and managing foot and ankle pain thought to be subserved by the tibial nerve. The technique is also useful for providing surgical anesthesia for the distal lower extremity when combined with common peroneal and saphenous nerve block or lumbar plexus block. It is used for this indication primarily in patients who would not tolerate the sympathetic changes induced by spinal or epidural anesthesia and who need distal lower extremity surgery, such as debridement or distal amputation.

Tibial nerve block at the knee with local anesthetic can be used as a diagnostic tool during differential neural blockade on an anatomic basis in the evaluation of lower extremity pain. If destruction of the tibial nerve is being considered, this technique is useful as a prognostic indicator of the degree of motor and sensory impairment that the patient may experience. Tibial nerve block at the knee with local anesthetic may be used to palliate acute pain emergencies, including ankle and foot fractures, and when awaiting pharmacologic methods to become effective. Tibial nerve block at the knee with local anesthetic and steroid is occasionally used to treat persistent ankle and foot pain when the pain is thought to be secondary to inflammation or when entrapment of the tibial nerve at the popliteal fossa is suspected. Tibial nerve block at the knee with local anesthetic and steroid is also indicated in the palliation of pain and motor dysfunction associated with diabetic neuropathy. Destruction of the tibial nerve at the knee is occasionally used in the palliation of persistent lower extremity pain secondary to invasive tumor that is mediated by the tibial nerve and has not responded to more conservative measures.

Clinically Relevant Anatomy

The tibial nerve is 1 of the 2 major continuations of the sciatic nerve, and the other is the common peroneal nerve. It provides sensory innervation to the posterior portion of the calf, the heel, and the medial plantar surface. The nerve splits from the sciatic nerve at the superior margin of the popliteal fossa and descends in a slightly medial course through the popliteal fossa ( Fig. 171.1 ). The tibial nerve block at the knee lies just beneath the popliteal fascia and is readily accessible for neural blockade. The tibial nerve continues its downward course, running between the 2 heads of the gastrocnemius muscle, passing deep to the soleus muscle. The nerve courses medially between the Achilles tendon and the medial malleolus, where it divides into the medial and lateral plantar nerves, providing sensory innervation to the heel and medial plantar surface ( Figs. 171.2 and 171.3 ). The tibial nerve is occasionally subject to compression at this point, which is known as posterior tarsal tunnel syndrome .