Table 2.

Numbers (percentages) of yes or maybe responses where relevant to the knowledge and willingness to participate questions.

Question	N (%)
Do you understand that when the benefits of a particular treatment are uncertain a clinical study (trial) is needed?
Yes	59 (95.2)
Did you know that some clinical trials use placebo surgery as a control (comparison) to the traditional surgery?
Yes	28 (45.2)
Do you understand what placebo surgery for lumbar spinal stenosis is?
Yes	19 (30.6)
If you were invited to participate in a study investigating the effects of surgery for lumbar spinal stenosis, would you be willing to participate?
Yes	42 (67.7)
If this study would involve patients to be randomly divided equally into two groups (by chance), one group receiving surgery and the other group receiving a placebo surgery, would you still be willing to participate?
Yes	10/42 (23.8)
Maybe	13/42 (30.9)
If you were allocated to a placebo surgery group, and later decided you would like to receive traditional surgery, would you be willing to wait for six months to do so?
Yes	12 (20.0)
Maybe	13 (21.7)