Metatarsal block

The metatarsal block is a simple and suitable block procedure providing good pain relief following surgical procedures on the toes [58]. It is typically carried out with the patient lying supine. A standard IM needle is inserted through the dorsum of the foot (Figure 9) and advanced in close contact with the medial border of the base of the metatarsal up to the sole. When the distal extremity of the needle is felt and seen as it pushes the skin of the sole, the local anesthetic is injected while the needle is slowly withdrawn. A volume of 1 to 3 mL of 0.25-0.5% plain bupivacaine or 0.2-0.5% ropivacaine is injected. The same procedure is repeated along the lateral border of the same metatarsal to provide full anesthesia of the relevant toe.

A still simpler technique for toe surgery consists of injecting a LA within the fibrous sheath which surrounds the synovial sheath of the flexor tendon of each toe and within which digital nerves supplying the toe are located. While the child is placed supine, the anesthesiologist locates by palpation the head of the relevant metatarsal bone on the sole of the foot. An intradermic needle is inserted perpendicularly to the skin, right in the center of the skin projection of this metatarsal head, until bone contact is made. To avoid sub-periosteal injection, the needle is then slightly with-drawn before injecting 1-3 mL of LA (until resistance is felt). Within 2 minutes all the nerves supplying the relevant toe are fully anesthetized in virtually all patients, thus allowing pain free surgery and postoperative pain relief for several hours. Both these
 techniques have many advantages over the "classical" ring block:
they are safer (no terminal artery in close proximity, virtually no
complication), simpler and less painful in conscious patients (even
though injection is not pain-free). Caution should be taken in case
of infection to avoid bacterial contamination of the synovial sheath
(in this case, the technique should be considered contra-indicated).


                                                                                                             Figure 9. Metatarsal block