Does Knee Surgery Actually Help?


LEAD STORY-DATELINE: The New York Times, July 11, 2002.

A study published in the New England Journal of Medicine claims that performing knee surgery to cure arthritis does not help the patient any more than pretending to do the surgery. The arthroscopic surgery is done on 225,000 Americans every year and involves making three small cuts in the knee, shaving rough areas of bone from the joint and then flushing it away.

One hundred eighty people participated in the study. They didn't know ahead of time whether they would have the operation or would be given the placebo (only three small cuts, no general anesthetic and no surgery). An envelope given to the doctor prior to the surgery indicated which group the patient fell into. After the surgeries and placebos, all of the patients were observed for two years. They all claimed that they felt better, regardless of which group they were in. On a scale determined by the physicians, patients in both groups had similar results. There were no objective differences between the patients who had the surgery and those who did not.

Several doctors who wondered if the placebo effect, and not surgery, was the cause of the pain relief initiated this investigation. Normally placebo studies of surgery are not done due to ethical concerns. In order to make the patient think that they are being operated on, some harm must be done to them and there is potential risk. To be ethical, three criteria must be met; 1) it must not place patients at undue risk, 2) the benefits must be worth any potential risk to the patient and 3) the patients must give informed consent. The researchers felt that all three criteria had been met in their study.


  1. What is the placebo effect and why is it important to test the placebo effect in surgery?

  2. Do you think it is ethical to run placebo studies on surgery patients? What are the possible risks? Would you agree to participate in such a study?

  3. The article states that while the statistics show the operation is not helpful, many orthopedic surgeons make their livelihood on this type of surgery. The article implies that whether it is helpful or not, people are making money on the operation and it probably will continue. Is this ethical?

  4. To determine if knee joint mobility had improved more for patients having had the surgery than for those who received the placebo, what statistical test would you use?

  5. The article states that the study was not large enough to be able to find small effects (small differences between the surgery and placebo groups). What does this mean?

  6. What does statistics bring to the study of placebos in surgery? Why can't we simply ask people if they feel better and consider it a success if they do?


This study represents one of the few efforts made at measuring the placebo effect in surgery. Given the results of this study, it may make sense to question the efficacy of other types of surgery. While the individuals participating in the study may be taking on risk, the potential benefit to future patients is immeasurable. It would seem that further placebo effect studies are warranted in light of the numerous surgeries performed in hospitals today.


"A Knee Surgery for Arthritis is Called a Sham," The New York Times, July 11, 2002.

-Sandra Strasser


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