Comparing the Ultrasound Appearance of the Sciatic Nerve With Its Appearance Under a Microscope

The investigators are proposing to conduct this study to compare the ultrasonographic appearance of the sciatic nerve with their corresponding histologic architecture. Patients that are scheduled to undergo above knee amputation due to complications associated with diabetes will be enrolled. We intend to do an ultrasound examination of the sciatic nerve at its bifurcation (about 4 inches above the knee). The investigators would mark the area on the skin where the image is obtained. Following surgery we will conduct a histologic examination of the nerve at the same site. Ultrasound examination is not standard of care, but is a fairly noninvasive procedure and does not add any risk to the subject. Histologic examination of the nerve is also not standard of care, but is conducted on a pathology specimen