Pain control infusion pumps: a prospective randomized evaluation in bilateral total knee arthroplasty

We prospectively monitored pain scores on 24 patients who underwent bilateral total knee arthroplasty (TKA). Patients were blinded to receiving either a functional or placebo pain control infusion pumps. After 3 days, pump volume was recorded, and patients were asked to identify which knee they believed received the functional pain control infusion pump. Fourteen patients (58%) correctly identified their knee with the functional pain control infusion pump. Pump volumes ranged from 70 to 310 mL, with an average flow rate of 4.3 mL/hour. Positive identification rates were similar to rates routinely generated from standard placebo symptom treatment pain trials (0%-60%). Our data suggest that the placebo effect plays at least a partial role in pain control infusion pump effectiveness, and that pain control infusion pump use for TKA unpredictably contributes to postoperative pain management. [corrected]