Combination of Peripheral Nerve Block and DepoDur in Total Knee Joint Replacement

7.5 mg Depodur via the epidural catheter

The sciatic nerve will be identified at the subgluteal level with ultrasound. A point 3 cm lateral and 4 cm caudad will be marked. Patients will be placed in the lateral position. A 18 G Tuohy needle will be inserted at a 45° angle until a peroneal or tibial twitch is obtained at 1.5 mA. Once the current can be reduced to obtain a twitch less than 0.5 mA, a catheter will be inserted and placed perineurally. If placed preoperatively, the catheter will be flushed with normal saline or 5% dextrose and will not be dosed until after surgery. After the patient is in the PACU and the surgeons have verified the sciatic nerve function, the sciatic catheter will be dosed with 35 mL 0.25% ropivacaine.