Background and Aims Use of ultrasound has revolutionized Regional Anesthesia techniques to provide adequate surgical anesthesia. Blockage of Sciatic nerve in popliteal fossa is common technique for surgeries involving foot & ankle. There are various approaches described to perform block. We decided to do observational study on volunteers for comparing posterior & lateral approach on following parameters:1.Need for external assistance for positioning2.Time taken to localize sciatic nerve3.Patient comfort4.Anesthetist satisfaction score.

Methods Scanning was done by same anesthetist with same machine in all volunteers.Time was recorded starting from positioning till sciatic nerve was localized.Fifty volunteers were divided in two groups on random basis.

1.GroupP[Posterior approach]:Scanning was performed in lateral decubitus or supine with knee flexed position.High frequency transducer placed in transverse position at Popliteal crease and Popliteal artery identified. Superficial and lateral to it hyperechoic oval/round structure tibial nerve identified. Transducer scanned proximally till tibial and peroneal nerve joined to form sciatic nerve.

2. GroupL[Lateral approach]:Scanning performed in supine position with limb in neutral position.Transducer placed in transverse position perpendicular to skin proximal to popliteal crease level.Scanning done proximally till hyperechoic sciatic nerve surrounded by hypo echoic muscles & hyper echoic shaft femur shadow identified.

Results No external assistance for positioning needed in GroupL compared toGroupP. No adjustments in limb position needed in GroupL while flexion/extension of hip needed in GroupP. Time to localize nerve was less in GroupL. Anesthetist satisfaction score higher in GroupL.

Conclusions We concluded that Lateral approach is simple & convenient for both patients and anesthetists & should be practiced more often.