Digital anaesthesia through the flexor tendon sheath at the palmar level

Sixty five patients with various traumatic lesions of the fingers have been operated on under digital anaesthesia using 3 ml of 2% Mepivacaine injected into the flexor tendon sheath. The anaesthesia was adequate for surgery in all instances except in one patient. No complications were encountered with this technique. The authors studied the mechanism of action by dissecting a cadaveric hand after injecting a tracer (Methylene blue) in place of the local anaesthesia, suggesting, but not proving, that anaesthesia is achieved by blocking the nerve in the area of the injection.