Answer the questions after the following article summary.
A study ${ }^{7}$ was carried out on human volunteers to see whether two procedures performed during arthroscopic surgery \{arthro-,
joint $+$ scopium, to look at \} are effective in relieving knee pain associated with osteoarthritis, or degenerative joint disease \{asteon, bone $+$ arthro-, joint $+$-itis, inflammation $\}$. The volunteers were up to 75 years old and were recruited from a Veterans Affairs Medical Center. They were $93 \%$ male and $60 \%$ white. One-third of the subjects had placebo operations that is, they were given anesthesia and their knees were cut open, but the remainder of the treatment procedure was not done. The other two-thirds of the subjects had one of the two treatment procedures performed. Subjects were followed for two years. They answered questions about their knee pain and function and were given an objective walking and stairclimbing test. At the end of the study, the results showed no significant difference in knee function or perception of pain between subjects getting one of the standard treatments and those getting the placebo operation.
a. Do you think it is ethical to perform placebo surgeries on humans who are suffering from a painful condition, even if the subjects are informed that they might receive the placebo operation and not the standard treatment?
b. Give two possible explanations for the decreased pain reported by the placebo operation subjects.
c. Analyze and critique the experimental design of this study. Are the results of this study applicable to everyone with knee pain?
d. Was this study a blind, double-blind, or double-blind crossover design?
c. Why do you think the investigators felt it was necessary to include a placebo operation in this study?