Effects of local infiltration analgesia for posterior knee pain after total knee arthroplasty: comparison with sciatic nerve block.

BACKGROUND: Although femoral nerve block provides good analgesia after total knee arthroplasty (TKA), residual posterior knee pain may decrease patient satisfaction. We compared the efficacy of periarticular infiltration analgesia (PIA) and sciatic nerve block (SNB) for posterior knee pain.

METHODS: Forty-nine patients scheduled for TKA were prospectively randomized into the PIA group (n = 25) or SNB group (n = 24) and received general anesthesia with ultrasound-guided femoral nerve block (FNB). In the PIA group, 60 ml 0.5% ropivacaine and 0.3 mg epinephrine were injected intraoperatively into the periarticular soft tissue before inserting the components. In the SNB group, patients received ultrasound-guided SNB with 20 ml 0.375% ropivacaine and periarticular infiltration with 20 ml normal saline and 0.3 mg epinephrine. We evaluated postoperative pain scores, posterior knee pain, frequency of rescue analgesics for 36 h, and performance time of PIA and SNB.

RESULTS: Visual analogue pain scores at 12-24 h were significantly lower in the PIA group than in the SNB group (p < 0.05). The majority of patients had no posterior knee pain. There were no significant differences between the groups in frequency and time of first administration of rescue analgesics and in side effects. Time for performance of periarticular infiltration was significantly shorter than that for SNB (p < 0.05). The dose of intraoperative remifentanil was significantly lower in the SNB group than in the PIA group (p < 0.001).

CONCLUSIONS: The combination of FNB and PIA provides sufficient analgesia after TKA. The rapid and convenient periarticular infiltration technique could be a good alternative to SNB.