Single injection digital block: is a transthecal injection necessary?

Three different methods of injection to obtain digital block anaesthesia were performed on 15 healthy volunteers to evaluate the success and extent of anaesthesia. We found that the traditional transthecal injection technique was inaccurate and the injected agent mainly flowed into the subcutaneous space, and did not remain within the sheath. The deep transthecal single injection kept the anaesthetic agent within the flexor tendon sheath, as intended. The duration of anaesthesia and the area anaesthetised by the subcutaneous injection and the traditional transthecal injection was similar and satisfactory. However, the anaesthetic area after the deep transthecal injection was significantly smaller than that of the other two techniques (P<0.01). A transthecal digital block offers no advantage over a simple subcutaneous digital block.