"Our study found that the risk of developing a serious joint infection that required an additional knee revision surgery was two times higher in patients who had staged knee replacements compared to the patients who had both knees replaced at the same time (2.2 percent after staged knee replacements and 1.2 percent after bilateral knee replacements)," said John P. Meehan, MD, study author and orthopaedic surgeon from the University of California, Davis.