Tibial nerve blockade is used to treat pain disorders in the tibial nerve distribution of the foot.
After informed consent is obtained, the patient is placed in the prone position with the foot supported by a pillow. The patient is prepared in a standard aseptic fashion over an area large enough to allow palpation of landmarks, and sterile technique is used throughout the procedure. A skin wheal is raised along the medial aspect of the Achilles tendon at the level of the superior border of the medial malleolus. A 1-in. (2.5-cm), 25-gauge needle is advanced through the wheal toward the posterior aspect of the tibia, behind the posterior tibial artery. If a paresthesia is elicited after negative aspiration, 3 to 5 mL of local anesthetic is injected after negative aspiration. If a paresthesia is not elicited, the needle is advanced until the tibial periosteum is contacted. The needle is withdrawn 0.5 cm, and after negative aspiration, 5 to 7 mL of local anesthetic is injected to block the posterior tibial nerve. A nerve stimulator may be used to identify the posterior tibial nerve by eliciting contraction of muscles in the sole of the foot (Fig. 67-19).
FIGURE 67-19. Nerve blocks at the ankle. Approach for nerve injection and neural blockade at the ankle.
The posterior tibial nerve is located along the medial aspect of the Achilles tendon, lying just behind the posterior tibial artery. The nerve gives off a medial calcaneal branch to the medial aspect of the heel, then divides behind the medial malleolus into the medial and lateral plantar nerves. The medial plantar nerve supplies the medial two thirds of the sole of the foot as well as the plantar portion of the medial three and onehalf toes. The lateral plantar nerve supplies the lateral one third of the sole and the plantar portion of the lateral one and onehalf toes.
Intraneural injection may result in nerve damage. Severe pain on injection suggests the possibility of an intraneural injection, and the needle should be repositioned immediately. Hematoma and intravascular injection are possible due to the close proximity of the posterior tibial vessels. If an arterial puncture occurs, prolonged direct pressure is usually adequate to prevent the development of a hematoma.