The Effect of Leg Position on the Sciatic Nerve on Sonogram

Study Overview
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Brief Summary
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Little is known about which posture of lower extremity makes it easier to access to the sciatic nerve. In this study, the investigators aimed to identify the most appropriate positioning of the lower extremity during anterior-approach ultrasound-guided sciatic nerve block.

Official Title
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Influence of Lower Extremity Positioning During Anterior-approach Ultrasound-guided Sciatic Nerve Block: Depth and Visibility

Conditions
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Sciatic Nerve Block

Intervention / Treatment
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* Behavioral: external rotation of leg
* Behavioral: hip flexion and knee flexion


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: ASA PS 1-3 patients undergoing knee surgery requiring peripheral nerve block Exclusion Criteria: patients who refuse to participate in the study BMI > 40 kg/m2 patients who have congenital abnormality on leg patients who have surgery or trauma on hip/knee patients who cannot move freely due to the contracture patients who are judged ineligible by the medical staff to participate in the study for other reasons

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 80 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Group N<br>Neutral position | |
| Group E<br>External rotation of leg by 45 degrees | Behavioral: external rotation of leg<br>* external rotation of leg by 45 degrees<br>|
| Group EF45<br>External rotation of leg by 45 degrees, hip flexion by 45 degrees, and knee flexion by 45 degrees | Behavioral: external rotation of leg<br>* external rotation of leg by 45 degrees<br>Behavioral: hip flexion and knee flexion<br>* hip flexion by 15/45 degrees and knee flexion by 15/45 degrees<br>|
| Group EF15<br>External rotation of leg by 45 degrees, hip flexion by 15 degrees, and knee flexion by 15 degrees | Behavioral: external rotation of leg<br>* external rotation of leg by 45 degrees<br>Behavioral: hip flexion and knee flexion<br>* hip flexion by 15/45 degrees and knee flexion by 15/45 degrees<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Visibility of sciatic nerve | Visibility of sciatic nerve at each position assessed using a scoring system (0, no nerve identified; 1, nerve identified with a high probability; 2, nerve identified, but most of it not visible; 3, nerve identified, more than 50% of its borders can be precisely distinguished from surrounding structures; 4, nerve completely visible, but fascicles poorly defined; 5, nerve completely visible and multiple fascicles identifiable.) | during 10 minutes of anesthesia induction | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Depth of sciatic nerve | Distance from skin to sciatic nerve at each position | during 10 minutes of anesthesia induction |