A Comparison of Two Injection Locations in Obese Patients Having Lower Leg/Foot Surgery

The purpose of this study is to compare two different techniques for placement of nerve blocks for your foot or ankle procedure. A nerve block involves injecting numbing medications around a nerve to decrease pain after surgery. An ultrasound machine is often used to help see the nerve before injecting the numbing medicine. When an ultrasound machine is used during a block it is called an ultrasound-guided block.

Many studies of ultrasound-guided nerve blocks have involved mostly thin patients, especially from foreign countries. This study is different because the investigators are looking at patients living in America with a body mass index (a measure of the amount of body fat a person has) of more than 35.

The Sciatic nerve is a large nerve that provides most of the feeling and all of the movement to the foot and ankle. The nerve travels under the back of the leg, and splits into two smaller nerves slightly above the knee.

Inclusion criteria

• Patients ≥ 18 years of age undergoing unilateral foot and/or ankle surgery
• Severe or morbid obesity, defined as a BMI of 35-39 or ≥ 40, respectively
• ASA status I-IV
• Ability to understand and provide informed consent

Exclusion criteria

• True allergy, not sensitivity, to any of the following substances:

Local Anesthetics Midazolam Fentanyl Hydromorphone Propofol

• Pregnancy
• Evidence of infection at or near the proposed needle insertion site
• Unstable or undetermined neurologic disease of the lower extremity
• Chronic pain patients
• Patient refusal or inability to provide informed consent