Transthecal digital block: flexor tendon sheath used for anesthetic infusion.

A new approach to achieve digital block by use of the flexor tendon sheath as an avenue introducing anesthetics to the core of the digit is described. Through centrifugal anesthetic diffusion all four digital nerves are anesthetized rapidly. This technique involves palmar percutaneous injection of 2 ml of lidocaine (Xylocaine) into the potential space of the flexor tendon sheath at the level of the palmar flexion crease with a 3 ml syringe and a No. 25-gauge hypodermic needle. Over the last 5 years, I have used this technique on 420 patients with no observable anesthetic complication. A repeat injection or local infiltration as a supplement was necessary only in four instances.