Long-Acting Pain Control Improves Knee Replacement Outcomes

Injecting a long-acting anesthetic into surrounding tissues during total knee replacement (TKR) surgery may provide a faster recovery and higher patient satisfaction, according to a new study.

Researchers at Henry Ford Hospital (Detroit, MI, USA) conducted a study from October 2012 to September 2013 to evaluate 216 patients for pain control during the first two days after TKR surgery. Half of the patients received the traditional pain control method of continuous nerve blockade, in which common local anesthetic is administered using an infusion pump to blunt the femoral nerve, which runs anterior to the knee. The other half of patients received an injection of the long-acting anesthetic liposomal bupivacaine at the site of the surgery.

The results showed that the pain scores for the liposomal bupivacaine injection technique averaged about 3/10, similar to the pain scores seen with the traditional pump infusion method. The patients reported pain relief for up to two days after surgery, and better knee function as compared with the traditional method, being able to walk comfortably within hours after surgery. The liposomal bupivacaine injection technique also lacked the side effects of the traditional technique. The study was presented at the American Association of Hip and Knee Surgeons meeting, held during November 2014 in Dallas (TX, USA).

“Function-wise, it was a lot easier for patients to move around more confidently. Pain control came at the price of weakness, and made patients somewhat tentative when walking during their hospital stay,” said senior author and study presenter Jason Davis, MD. “In the past decade, we've made major advancements in pain control for knee replacement surgery. This option is a promising, viable one for our patients."

Liposomal bupivacaine consists of bupivacaine loaded in multivesicular liposomes, carrier molecules that increase the duration of local anesthetic action by slow release from the liposome, delaying the peak plasma concentration. The median time from anesthesia to pinprick sensation is 35 hours for all doses of liposomal formulations, compared to 11 hours for bupivacaine HCl. Its kinetics are also favorable, even in patients with moderate hepatic impairment, and it has been found not to delay wound healing after orthopedic surgery.

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