Version July 2025
The modified transthecal block (or flexor tendon sheath digital block) is performed by infusing the flexor tendon sheath with an anesthetic solution through a single injection.
(A) The injection site is either at the proximal digital crease (proximal dashed line) or at the midpoint between the proximal digital and proximal interphalangeal joint creases (dot).
(B) The needle is inserted at a 90-degree angle (being shown inserted at the midpoint).