Effect of single-injection versus continuous local infiltration analgesia after total knee arthroplasty: a randomized, double-blind, placebo-controlled study.

In this randomized, double-blind, placebo-controlled, single-centre study, 80 patients (American Society of Anesthesiologists physical status I-III) received postoperative single-injection local infiltration analgesia (SLIA), continuous local infiltration analgesia (CLIA) or placebo (control group). Intravenous patient-controlled morphine was used as rescue analgesia. The CLIA group showed lower postoperative visual analogue scale (VAS) pain scores from 8 to 48 h at rest and from 16 to 48 h during activity compared with the SLIA group. The CLIA group also had significantly lower consumption of morphine from 24 to 48 h postoperatively versus the SLIA group. Patient satisfaction was higher, and maximum flexion of the knee on postoperative days 7 and 90 was greater, in the CLIA group compared with the SLIA group. CLIA provided prolonged superior analgesia and was associated with more favourable functional recovery and patient satisfaction compared with SLIA.