One more reason to think twice before you have arthroscopic knee surgery for osteoarthritis: a study published in the New England Journal of Medicine suggests that the procedure does no better at relieving symptoms than physical therapy or anti-inflammatory drugs. What's more, patients who do feel improvement after surgery may merely be experiencing a placebo effect. This finding echoes a 2002 government study showing that outcomes were similar whether a patient underwent real arthroscopic surgery or a sham procedure in which an incision was made but no actual work was done. That study prompted Medicare to drop coverage for the surgery as a treatment for osteoarthritis.