An RCT pilot-study was conducted to assess efficacy of a 48-h continuous local infiltration of intra-articular bupivacaine (0.5% at 2 cc/h) versus placebo (0.5% saline at 2 cc/h) in decreasing PCA morphine consumption following TKA. Secondary outcomes included 48-h VAS pain, opioid side effects, length of stay, and knee function scores up to 1-year postoperatively. Of 67 randomized patients, 49 completed the trial including 24 bupivacaine, and 25 placebo patients. Mean 48-h PCA morphine consumption did not differ significantly between treatment (39 mg ± 27.1) and placebo groups (53 mg ± 30.4) (P = .137). The intervention did not improve pain scores, or any other outcome studied. Given study results we would conclude that analgesia outcomes with a multimodal analgesia regimen are not significantly improved by adding 48 h of 0.5% bupivacaine infiltration at 2 cc/h.
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