ULTRASOUND-GUIDED SCIATIC POLITEAL NERVE BLOCK: A COMPARISON OF SEPARATE TIBIAL AND COMMON PERONEAL NERVE INJECTIONS VERSUS INJECTING PROXIMAL TO THE BIFURCATION.

Objective: Block of the sciatic nerve at the popliteal fossa can be performed using the ultrasound machine; it may be proximally or distally to the bifurcation of the sciatic nerve using lateral, medial, or posterior approaches. It is frequently used for surgeries below the knee specially the foot and ankle operations.

Purpose: This study compares one and two injections of the sciatic nerve in the popliteal fossa with ultrasound-guided block in foot or ankle surgeries.

Methods: Forty patients received ultrasound-guided sciatic nerve block with the nerve stimulator, using the posterior approach. The patients were enrolled into two groups (20 patients each), group 1: received one injection at 2 cm cephalad to the bifurcation of the sciatic nerve, and group 2: received two injections caudate to the sciatic bifurcation; one for tibial nerve and the other for common peroneal nerve. All patients received 20 ml of levobupivacaine 0.5%. The block performance time, block efficacy, success rate, complications and patient's satisfaction were evaluated.

Results: Block the tibial and common peroneal nerves separately (two injections) distal to the point of bifurcation of the sciatic nerve has a significantly (P < 0.05) faster time to complete sensory block of tibial and common peroneal nerves compared to a pre-bifurcation sciatic nerve block (one injection). The complete motor block, block time performance, success rate and patient's satisfaction were not significantly different between groups (P > 0.05).

Conclusion: The block of tibial and common peroneal nerves separately distal to the sciatic nerve bifurcation is superior to single injection block of sciatic nerve above the bifurcation in the popliteal fossa as regard complete sensory block time.