Arthroscopic surgery and placebo

Townsend Letter for Doctors and Patients,  Jan, 2005  by Robert A. Anderson

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One hundred eighty patients with osteoarthritis of the knee were randomly assigned to receive arthroscopic debridement, arthroscopic lavage, or placebo surgery. Patients in the placebo group received skin incisions and underwent a simulated debridement without insertion of the arthroscope. Patients and assessors of outcome were blinded to the treatment-group assignment. Outcomes were assessed at multiple points over a 24-month period with the use of five self-reported scores--three on scales for pain and two on scales for function--and one objective test of walking and stair climbing. A total of 165 patients completed the trial. At no point did either of the intervention groups report less pain or better function than the placebo group. M scores on the Knee-Specific Pain Scale (range, 0-100, with higher scores indicating more severe pain) were similar in the placebo, lavage, and debridement groups: 48.9, 54.8 and 51.7, respectively, at one year (p=0. 14=NS for the comparison between placebo and lavage, p=0.51=NS for the comparison between placebo and debridement) and 51.6, 53.7 and 51.4, respectively, at two years (p=0.64 and p=0.96, both NS, respectively). The 95% confidence intervals for the differences between placebo and intervention groups exclude any clinically meaningful difference.

Moseley JB Jr. O'Malley K, Petersen NJ et al. A controlled trial of arthroscopic surgery for osteoarthritis of the knee. N Engl J Med 2002 Jul 11;347(2):81-8

COMMENT: In this controlled trial involving 180 patients with osteoarthritis of the knee, outcomes after arthroscopic lavage or arthroscopic debridement were no better than those after a placebo procedure. Here we have adequate numbers for surgical analysis, and the results echoed the original pilot study in 1996. So what are we to conclude about pain and placebo? The perception of pain has an extremely large subjective component in which one's belief system plays an enormous role. Medical students are unfortunately not generally taught a lot about the power of suggestion, and the influences of the mind on perceptions--of pain, illness or state of health.

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