Ultrasound Guidance Versus Electrical Stimulation for Continuous Popliteal-Sciatic Nerve Blocks

Specific Aim 1: To determine the relationship between perineural catheter placement technique (ultrasound-guidance and electrical stimulation) and quality of postoperative analgesia during continuous popliteal-sciatic nerve blocks following moderate-to-severely painful orthopedic surgery. Hypothesis 1: When inserting a perineural catheter for a continuous peripheral nerve block, the use of electrical stimulation, as compared with ultrasound-guidance, is associated with decreased pain the morning following moderate-to-severely painful orthopedic surgery as measured with a numeric rating scale. Specific Aim 2: To determine the relationship between perineural catheter placement technique (ultrasound-guidance and electrical stimulation) and degree of sensory deficit during continuous popliteal-sciatic nerve blocks following moderate-to-severely painful orthopedic surgery. Hypothesis 2: When inserting a perineural catheter for a continuous peripheral nerve block, the use of electrical stimulation, as compared with ultrasound-guidance, is associated with increased sensory deficit the day following moderate-to-severely painful orthopedic surgery as measured with a simple 0-10 scale (0=no numbness; 10=completely insensate) of the part of the foot with the greatest sensory deficit at the time of the data-collection phone call.