Post operation neuropathy of common peroneal nerve resulting in foot drop

Common peroneal nerve (CPN) neuropathy resulting in foot drop is a relatively uncommon complication of patients who are positioned in the lithotomy position during surgery, and the most common cause of spontaneous painless foot drop. Although diagnosis is often based on the clinical findings, ultrasound can be used as an efficient and effective imaging tool to identify the cause of CPN neuropathy and other peripheral nerve disorders. In this article, two ultrasound cases of patients with post operation foot drop as a result of CPN neuropathy are presented. The anatomy, ultrasound imaging technique, ultrasound appearance of CPN neuropathy; and potential causes of CPN are described.