Posterior tibial nerve block achieves sensory blockade to the anterior two thirds of the sole of the foot (not including the webspace between the big toe and second toe)
The posterior tibial nerve lies on the medial aspect of the ankle, between the medial malleolus and the Achilles tendon, deep to the flexor retinaculum. The posterior tibial artery can usually be felt behind the medial malleolus. The nerve lies just posterior to this artery (i.e. closer to the Achilles tendon).
If the artery cannot be palpated, the point of injection should be estimated at the halfway point between the medial malleolus and the achilles tendon.
All injections should occur at the level of the upper edge of the medial malleolus.
It is useful for painful procedures or injuries involving the sole of the foot (i.e. removal of foreign bodies and wound repair)
A nerve block avoids the need for painful and difficult infiltration of local anaesthetic into the dense skin and subcutaneous tissue of the sole