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Adding Peripheral Nerve Blocks to Injections Improves Knee Replacement Care

Adding peripheral nerve blocks to routine periarticular injections for total knee replacements has been linked to less post-operative pain and lower opioid consumption, according to research presented at the 2018 World Congress on Regional Anesthesia and Pain Medicine. This study, lead by Hospital for Special Surgery (HSS) researchers, received ASRA’s 2018 Best of Show award.

The rate of ambulatory surgery is expected to grow 51 percent by 2026, and to meet this increase in volume ambulatory centers are looking for ways to optimize post-operative pain management in the setting of increasingly common fast-track strategies. To that end, many surgeons use periarticular injections (PAIs) for total knee arthroplasties (TKAs). PAIs help reduce postoperative pain, but there are opportunities to further improve patient care and reduce opioid consumption, explained Jonathan Beathe, MD, co-author, and anesthesiologist within the Department of Anesthesiology, Critical Care & Pain Management at HSS.

"In order for patients to start moving after TKA earlier while using less opioids, anesthesiologists and surgeons should collaborate to use different methods of analgesia," explained Dr. Beathe. "This includes adding nerve blocks to periarticular injections. These nerve blocks target the sensory nerves that spare motor function and facilitate early ambulation and rehabilitation, a major goal for patients undergoing TKA."

A team of investigators examined whether adding motor-sparing peripheral nerve blocks (MSBs) to a PAI would lower pain in the postoperative period compared to PAI alone. The MSBs used in the study were the adductor canal block (ACB) and the interspace between the popliteal artery and capsule of the posterior knee (IPACK) block. 

The investigators randomly assigned 86 patients undergoing a TKA to receive either a PAI (n=43), or an IPACK and ACB with modified PAI injection (n=43). To determine the efficacy of these combined anesthetic approaches, the researchers compared post-operative pain levels, numeric rating scale (NRS) pain scores, pain outcomes, and opioid consumption.

On post-operative day 1, the group that received a combination of IPACK block and ACB with PAI reported lower NRS pain scores compared with the group who received PAI only (1.7 versus 5). There was a significant difference in pain scores on ambulation on post-operative day 0 (1.7 versus 5.2) and on post-operative day 3 (4.5 versus 5.5). The group who received the IPACK and ACB with PAI intervention also reported lower pain scores after physical therapy on post-operative day 0 and 1 (1.9) compared with the PAI group (1.4).

"Patients who received an IPACK and ACB in addition to a PAI were overwhelmingly more satisfied," said David Kim, MD, anesthesiologist and principal investigator of the study. "Those who received the combination intervention reported less interference from pain when walking, less opioid consumption in the Post-Anesthesia Care Unit (PACU), less intravenous patient-controlled analgesia and less intravenous opioids compared to the patients who received PAI alone."

While there was no difference in hospital length of stay, more patients in the IPACK/ACB group were discharged on post-operative 0 and post-operative day 1 (5 percent and 19 percent, respectively) compared to those who received PAI only (0 and 16 percent, respectively).

"Anesthesiologists and surgeons should consider adding the IPACK block and ACB to a modified PAI to manage pain control in patients undergoing TKA more effectively," said Dr. Kim. "This collaborative anesthetic approach should be considered as part of a multimodal analgesic pathway for TKAs."


Kim, David MD, Lin Yi MD PhD, Beathe, Jonathan MD, Goytizolo, Enrique MD, Oxendine, Joseph MD, YaDeau, Jacques MD PhD, Maalouf, Daniel MD MPH, Garnett, Christopher BA, Ranawat, Amar MD, Su, Edwin MD, Mayman, David MD, Westrich, Geoffrey MD, Alexiades, Michael MD, Memtsoudis, Savros, MD PhD. "The addition of ACB and IPACK to PAI enhances postoperative pain control in TKA: A randomized controlled trial." Poster presented at: 2018 World Congress on Regional Anesthesia and Pain Medicine; April 19-21, 2017; New York, NY.