Unplanned hospital readmissions following elective hip and knee replacements fell 20% and 23%, respectively, between 2009 and 2013 among adults aged 50-84 enrolled in Medicare Advantage plans provided by a large U.S. insurance carrier, according to a new study by the AARP Public Policy Institute. The decreases were largest for adults aged 65 and older, although hip and knee replacements were not added to the Medicare Hospital Readmission Reduction Program until the end of 2014. Among adults aged 65 and older, device complications were the leading cause of hospital readmission after hip replacement and the second leading cause of readmission after knee replacement in 2013, the study found. The number of hip replacements among plan members aged 50-84 increased 73% between 2009 and 2013, while the number of knee replacements increased 46%.