Orthopedists failed to disclose over 20% of the payments they receive from makers of hip and knee replacements when presenting research related to the companies' products, a new study found. In the study, researchers measured the accuracy of disclosures by orthopedic surgeons who presented research at the March 2008 annual meeting of the American Academy of Orthopaedic Surgeons, by comparing the doctors' disclosures against a similar list published by five makers of hip and knee implants.