Canadian Journal of Anesthesia, Vol 12, 465-474, Copyright © 1965 by Canadian Anesthesiologists' Society

Regional Anaesthesia for the Foot

¹ Department of Anaesthesia, Lagos University Teaching Hospital, Lagos, Nigeria

1 In our study of anaesthetic techniques for the foot, the courses and distri–bution of the nerves supplying the foot were outlined in detail.

2 A series of 100 cases of foot blocks was carried out, involving one or more of the four nerves innervating the foot, depending on the site of the lesion.

The sole was anaesthetized by a posterior tibial nerve block behind the medial malleolus, and analgesia was complete in 88 per cent of the cases.

The dorsum was anaesthetized by a lateral popliteal nerve block at the posterior aspect of the neck off the fibula, with complete analgesia in 90 per cent of the cases.

The lateral portion of the foot was anaesthetized by a sural nerve block below the lateral malleolus, with complete analgesia in 90 per cent of the cases.

The medial part of the foot was anaesthetized by a saphendms nerve block anterior to the medial malleolus, and analgesia was complete in all cases.

3 The areas of analgesia mapped out following the blocks for the most part reflected the textbook picture of sensory distribution There were, however, two patterns of variation which occurred with some degree of frequency.

a The sural nerve required blocking for many dorsal lesions because it.

extended medially to include the fourth toe in 40 per cent of the cases No doubt this was due to the presence of its communicating branch to the musculo–cutaneous nerve Thus any dorsal lesion extending laterally beyond the third toe required suial blocking.

b The saphenous nerve presented problems of anomaly in some 10 per cent.

of the cases, usually extending forward only to the metatarso–phalangeal joint of the big toe Rarely was the medial portion of the great toe innervated by the saphenous nerve, but if this was the case with surgery involving this toe, the nerve was blocked easily as described.

Briefly then we may consider the site of the lesion and the nerve blocks required Any dorsal lesion lequires a lateral popliteal nerve block, and if the lesion extends to or beyond the fourth toe, a sural block is necessary as well Seldom is a sural block done alone Toe lesions generally require lateral popliteal and posterior tibial nerve blocks Any lesion involving the medial side of the foot necessitates a saphenous nerve block unless it is well forward on the side of the big toe The sole is nicely anaesthetized by a posterior tibial block.

We were pleased with the results of this series These blocks are now used by all anaesthetists in our department for surgery of the foot when regional anaesthesia is desirable All out–patient and casualty procedures can be carried out with this form of analgesia, and much of the surgery in the main theatre as well, when a tourniquet is not necessary The nerve blocks are simple to perform,work rapidly and predictably, and can be mastered within a short time by any physician interested in the foot.