Despite the proven effectiveness of total joint replacement (TJR) surgery in relieving advanced knee and hip arthritis pain, TJR outcomes have come under intense public scrutiny in recent years. The 2010 recall of ASR metal-on-metal hip implants1 heightened awareness of the importance for implant safety surveillance for this high-cost and high-use procedure and exposed the need for a national systematic patient-centered outcomes monitoring system. These safety concerns and the exponential growth in TJR use—given the demographics of the baby boomer generation—emphasize the need for systematic comparative effectiveness research (CER) to inform patients, physicians, and policy makers about the optimal practices in TJR surgery.