For this study, we based our analysis on FDA assignments of medical devices to 1 of 3 classes “based on the level of control necessary to assure the safety and effectiveness of the device”6(p1) and on the level of risk the device poses to patients. Class I devices involve the lowest risk and include items such as tongue depressors, bandages, and crutches. Class II devices, such as electrocardiographs, contact lens solutions, hearing aids, and drills for orthopedic applications, involve intermediate risk. And Class III devices are defined by the FDA to pose the greatest potential risk and include such items as implantable pacemakers, stents, heart valves, and human immunodeficiency virus diagnostic tests. Although implants and devices that prevent impairment of health are supposed to be Class III, many hip and knee implants are designated as Class II.