Comparative evaluation of two methods of prolonged femoral nerve block using an elastomeric pump after knee arthroplasty: a prospective randomized controlled study

BACKGROUND: The number of knee arthroplasty (KA) surgeries is increasing annually. These surgeries are associated with severe pain. The optimal method of choice in perioperative analgesia in these patients remains controversial. The use of regional analgesia, including prolonged analgesia, allows for high pain relief and increased patient satisfaction. Modern elastomeric pumps (EP) provide prolonged conduction analgesia, which significantly expands the possibilities of perioperative pain relief.

OBJECTIVE: To evaluate the effectiveness of prolonged femoral nerve block using EP with and without bolus after KA.

MATERIALS AND METHODS: This prospective randomized study included 75 patients who were divided into two clinical groups: group 1 (n=36), patients who received prolonged regional analgesia using EP with controlled injection without bolus, and group 2 (n=39), patients who received prolonged regional analgesia using EP with bolus. In the postoperative period, the level of pain at rest and during movement was assessed after 6, 12, 24, and 48 hours as well as the need for opioid analgesics, consumption of local anesthetic for various options of continued regional analgesia, quadriceps femoris muscle function, and distance traveled by patients after surgery in the first 2 days.

RESULTS: No significant differences were noted in pain level at rest and during movement in the observation period between the groups (p=0.213). No additional prescription of opioid analgesics was required. Local anesthetic consumption was lower in group 2 (group 1.384±33.4 ml; group 2.237±25.1 ml; p=0.031). Patients in group 2 had greater activity in knee extension and, thus, greater distance traveled after surgery.

CONCLUSION: The use of EP with a bolus has been demonstrated to provide adequate levels of analgesia and better functional recovery in patients with bolus after KA than in patients without bolus. This technique is recommended as a component of enhanced recovery program after surgery.