Transsartorial approach for saphenous nerve block.

Abstract

Blockade of conduction in the saphenous nerve is important in providing surgical anaesthesia in the lower leg. Unfortunately, previously described techniques have lacked clinical effectiveness in practice. We developed a transsartorial approach for conduction block of the saphenous nerve. We first confirmed its potential clinical utility in 12 cadaveric specimens by demonstrating that the saphenous nerve was consistently stained by injections of methylene blue. Subsequently, we compared the relative rates of successful saphenous nerve block and the extent of conduction block provided by three techniques: (1) transsartorial saphenous nerve block (TSSNB), (2) above knee femoral paracondylar field block (FPFB), and (3) below knee field block (BKFB) of the saphenous nerve in 20 ASA I volunteers. The transsartorial saphenous nerve block proved to be highly successful (80% success rate) and was superior to the other two approaches in providing cutaneous analgesia to pinprick in the saphenous nerve distribution (P < 0.05). The success rates of the BKFB and FPFB were 65% and 40% respectively. A successful block with the transsartorial approach provided complete anaesthesia of the medial malleolus in 94% of subjects whilst the BKFB and FPFB provided complete anaesthesia of the medial malleolus in less than 40% of the successful blocks. We recommend the transsartorial approach for more effective block of the saphenous nerve.