Prospective Randomized Trial Comparing Femoral Nerve Block With Intraoperative Local Anesthetic Injection of...

Postoperative pain after total knee arthroplasty (TKA) may impact long-term results and incidence of complications. Femoral nerve block (FNB) provides excellent pain relief after TKA, although associated risks include weakness, delayed participation in therapy, and nerve injury. Liposomal bupivacaine (LB) is a potentially longer acting local anesthetic that may reduce postoperative pain.

We performed a prospective, randomized, double-blind study of 373 TKA patients randomized to receive either an FNB (control group), or an intraoperative periarticular injection (PAI) with LB and a placebo saline FNB (experimental group). Patients were evaluated with visual analog scores for pain, range of motion, performance of straight leg raise (SLR), walking distance, and Short Form-12 up to 1 year postoperatively.

Twelve and 24 hours postoperatively, the control group had significantly lower pain scores (mean 3.24 vs 3.87; P = .02) and higher range of motion (84.54° vs 78°; P < .001). The patients receiving LB PAI were significantly more likely to perform a straight leg raise 12 hours postoperatively (73% vs 50%; P = .0003). Patients in the LB (experimental) group scored better in the physical function component of the Short Form-12 (-23 vs -27, P = .01) 3 months postoperatively.

While pain scores were slightly lower in the control group in the first 24 hours after TKA compared with LB PAI, the magnitude of the difference was small, and excellent pain relief was provided by both interventions. Use of LB PAI in TKA is a reasonable alternative to FNB, which avoids the additional weakness and other risk associated with FNB procedures.