A Randomized Controlled Trial to Compare Two Techniques for Partial Digital Local Anesthetic Blocks

Abstract 

The administration of local anesthetic before surgery to the great toe is often associated with significant difficulties, delaying surgery and increasing risk. Anxious patients can faint, refuse injection, or withdraw the foot while an anesthetic is being delivered. Such events led us to consider whether delivering a small amount of anesthetic throughout the injection site, before the main injection, may reduce pain intensity and duration. This study was designed to test this possibility. A randomized controlled, single-blinded, parallel-grouped clinical trial was carried out with a sample of 50 patients. All study participants received each injection method (1 or 2 stage) to either the medial or lateral side of the great toe. The primary end points were pain intensity, measured by scores on a visual analogue scale and duration, recorded by the patient with a stopwatch. The 2-stage method was associated with less intense pain (reduced from moderate to mild visual analogue scale level) of a shorter duration. The differences were highly statistically significant. In the 2-stage method, it is believed that they were due to the initial infiltration of a small quantity of the anesthetic solution throughout the injection site, with the remainder being administered, after a 2-minute interval, into tissue that was predominantly anesthetized. This differs from raising a traditional bleb where a small amount of anesthetic is infiltrated into superficial tissue. The 2-stage technique is therefore recommended as the method of choice for adults.

Level of Clinical Evidence: 1

Keywords: anesthesia, hallux, injection, mepivacaine, surgery, toe