Surgery to replace the arthritic hip and knee joints is on the rise in the U.S., with more than 1.1 million replacement surgeries reported in 2009. While these surgeries improve pain, mobility and quality of life for most recipients, some patients are dogged by persistent muscular problems. Now, a cross-institutional team of researchers has found that a patient's susceptibility to muscle inflammation may be a measurable marker that can be used to predict how well that patient will recover from joint replacement surgery and to identify those patients who may be in need of a specialized rehabilitation plan.