A comparison of two approaches to sciatic nerve block

This study compared the posterior and popliteal fossa approaches for sciatic nerve block. Patients scheduled to undergo foot surgery were allocated randomly into one of two groups: group A (n = 20) received sciatic nerve block via the posterior approach and group B (n = 20) received a block using the popliteal fossa approach. All blocks were performed with the aid of a peripheral nerve stimulator and alkalinised 0.5% bupivacaine with 1 in 200,000 adrenaline was injected in a dose of 2 mg.kg-1. Nineteen of 20 blocks in group A were successful compared with nine of 20 in group B (p less than 0.01). There was no significant difference between the groups in respect of time to onset or duration of block. Patients in group B reported less discomfort during performance of the sciatic nerve block but required supplementary nerve blocks more frequently. We recommend the use of the posterior approach for sciatic nerve block.