NEW ORLEANS -- A long-lasting formulation of the analgesic bupivacaine (Exparel) can do as good a job reducing post-surgical pain among knee replacement patients as continuous femoral nerve blocks -- and reduce or eliminate the need for narcotics, researchers said here.
In a clinical trial comparison, patients who underwent total knee replacement and were treated with femoral nerve block registered an average pain score of 2.29, compared with a score of 1.82 for patients receiving liposomal bupivacaine (P=0.09), indicating that both treatments controlled pain, said, a private-practice orthopedist and researchers in Plano, Texas.
Action Points
- Note that this study was published as an abstract and presented at a conference. These data and conclusions should be considered to be preliminary until published in a peer-reviewed journal.
- Following total knee replacement, wound infiltration with liposomal bupivacaine compares favorably to a continuous femoral nerve block, with equivalent analgesia but with significantly less total narcotic consumption and with no quadriceps weakness from blocking the femoral nerve.
"However, the use of long-acting bupivacaine -- effective for at least 72 hours -- markedly reduced the number of doses of narcotics needed by the knee replacement patients to alleviate pain," Emerson told ѻý at the annual meeting of the American Academy of Orthopaedic Surgeons.
"We now use liposomal bupivacaine as our standard of care for patients undergoing knee replacement surgery," Emerson said. He suggested that the long-acting drug might be used in lieu of narcotics for any type of surgery.
In his retrospective, patient-matched study, the average patient who had post-operative pain relief with the femoral nerve block required 14.25 doses of narcotics to continue pain relief after the procedure. The patients on bupivacaine required an average 7.47 doses of narcotics (P<0.001). In hydrocodone equivalents, patients who received the femoral nerve block used 176.6 mg of hydrocodone while those who received bupivacaine used 82.2 mg of hydrocodone equivalents (P<0.001).
"As part of a multimodal program, long-acting liposome bupivacaine infiltration gives equivalent post-operative analgesia compared to a continuous femoral nerve block, but with significantly less narcotic medication," Emerson said.
"We predict this will replace traditional opioid-reliant management," he said.
Continuous femoral nerve block replaced spinal epidural as post-operative analgesia for patients undergoing knee replacement therapy, but it still meant that patients experienced gaps in pain relief requiring narcotic rescue, Emerson explained; ambulation was limited because the nerve block made the impacted leg weak, and treatment required administration of a technically difficult pain pump, which was also an added expense.
He said that bupivacaine made most of those shortcomings go away.
From Emerson's practice's database, the researchers analyzed 42 knees of 36 patients treated with bupivacaine from October 2012 to August 2013 and compared them with 38 knees of 36 patients treated with femoral nerve block between December 2011 and September 2012.
"We do use bupivacaine and it had been an absolute game-changer for management of pain," said , professor of orthopedics at the University of Arkansas Medical School in Little Rock. "We use it as sort of a cocktail with normal saline. We have had amazing results." Barnes, who commented on the study during a poster discussion session, was not part of the study.
In hand surgery procedures, about half of the 50 cc of the cocktail is administered before cementing the replacement joint, and half is administered after the procedure. "I am amazed at the number of my patients who come back to have their staples removed and have never had to take an oral drug for pain," Barnes said.
Session moderator chief of orthopedic surgery at the Stanford University School of Medicine in California, said, "Pain control after total knee replacement has a great impact on how patients get going. What this paper showed is that the local injection of this long-acting bupivacaine treatment is equivalent to femoral nerve block and used less narcotics. It gets the patients up and moving, it controls the pain, it shortens the length of stay, and the reduction in the use of narcotics means less gastrointestinal problems and less delirium."
Disclosures
Emerson disclosed relevant relationships with Medtronic, Biomet and Pacira.
Maloney disclosed relevant relationships with Abbott, Gilead, ISTO Technologies, Johnson & Johnson, Merck, Moximed, Pfizer, Pipeline Orthopaedics, TJO and Wright Medical Technology.
Barnes disclosed relevant relationships with Convatec DJO, Wright Medical Technology, ConforMIS, and DePuy.
Primary Source
American Academy of Orthopaedic Surgeons
Source Reference: Emerson, Jr. R, et al "Comparison of infiltration with long-acting bupivacaine to a femoral nerve catheter for total knee replacement," AAOS 2104; Abstract P124.