A nerve block technique which avoids the femoral nerve results in the need for less morphine and a potentially speedier recovery for patients undergoing orthopaedic surgery, according to a study published in the June issue of the journal Anesthesia & Analgesia.
For the study, 80 patients presenting for primary unilateral total knee arthroplasty were randomised to receive either a continuous ultrasound-guided adductor canal block with 0.2% ropivacaine or a sham catheter.
All patients received a preoperative single-injection femoral nerve block with spinal anaesthesia. Seventy-six patients completed the study.
The researchers evaluated cumulative IV morphine consumption 48 hours after surgery, as well as resting pain scores, pain scores during physical therapy on postoperative days 1 and 2, postoperative nausea and vomiting, and satisfaction with analgesia.
Results showed that infusing pain-control medication through a catheter in the adductor canal of the mid-thigh — rather than higher up near the femoral nerve — provided better pain control and prevented temporary weakness of the leg muscles. This allowed recovering patients to walk sooner with stronger legs and resulted in improved physical therapy participation. Patients also needed less morphine to control post-surgery pain.
“No one in the world has shown all these possible outcomes in the same study with the adductor canal technique,” said Neil Hanson, MD, Virginia Mason Medical Center, Seattle, Washington.
“Use of the adductor canal for pain-block infusion appears to improve safety and clinical outcomes, and reduces the length of time needed for hospitalization,” added co-author David Auyong, MD, Virginia Mason Medical Center. “All patients now get this nerve block at Virginia Mason as part of our standard work for knee replacement surgery.”