Why isn't is a sham if it's ineffective (worthless). Would fraud be a better term? Roger: did you have this operation? Isn't it likely that I would have been advised to have it if I had consulted an MD about my knee pain?
The words sham and fraud suggest that the surgeon was tricking patients into having a phony operation. But the surgeons had every reason to believe that the surgery would be effective. The surgery repaired or removed bad tissue, and the patients reported positive results.
I've had several knee surgeries, and I have arthritis in my knees, but I never considered the knee surgery described in the NY Times article.
Good point, about calling the knee surgery a "sham", as that it is a misuse of the term. But it was a quoted doctor who misused it.
The article is unclear on the most important point: did the operation help patients, or not? The study merely demonstrated that the operation helped patients no more than the placebo effect. Both were presumably positive in benefit.
You say "The placebo effect is controversial ..." Only to materialists, who likewise deny other all other phenomena which defy materialistic explanation. Medical studies, meanwhile, are designed to address the placebo effect, including the knee surgery study.
I once had a surgeon try to talk me into wrist surgery. He even suggested that the surgery could be worthwhile even if he failed to find the problem. He said the surgery gets people to rest their wrists for a couple of weeks, and then they are more like to follow instructions of physical therapy. I was not impressed by this argument. At least he had a materialistic explanation for why the surgery would work.