That's a relief

Knee pain illustration

There are more than 60,000 knee replacements in Canada annually, making it the most common surgery in the country after C-section delivery. During the operation, systemic pain relief is given intravenously, with or without a femoral nerve block, which silences movement and sensory signals from the femoral nerve that runs from the spine all the way down the leg. Such blocks are effective, but they can also cause weakness, which delays physiotherapy and increases the risk of falls. In contrast, a regional technique called local infiltration analgesia (LIA) doesn’t cause motor block, thereby enabling faster recovery and discharge from hospital. 

Comic illustration

"Any improvement since I brought the balloon?"

About 30% of patients who have a knee replacement are beset with chronic pain. Doctors are unsure which approach best relieves suffering and improves outcomes. To address this knowledge gap, Dr. Stephen Choi, a researcher in the Holland Bone and Joint Research Program at Sunnybrook Research Institute, led a trial comparing LIA with a femoral nerve block that was given once, and one that was given continuously for 48 hours. One hundred and twenty people who had the surgery were randomly assigned to one of the three interventions. Neither the participants nor health care providers knew which method was used.

There were no significant differences in pain between the three methods two days after the operation. In a study published in Anesthesia & Analgesia, Choi and colleagues concluded that the optimal means of relief depends on many factors, and that most patients without chronic pain or who are not taking opioids daily will have satisfactory results using any of the three means.