Most patients who have had total knee or hip replacements aren’t more physically active six months after surgery, even though they report less pain and a better quality of life, a recent review has found.

Higher life expectancy and the growing recognition of the benefits of staying mobile at older ages have led more people to have the procedures. An estimated 11 million Americans are expected to have had one of these surgeries by 2030.

Studies of post-surgery outcomes have shown improvements in mobility, aerobic capacity, pain and depression. Duke University School of Medicine researchers say, however, that little attention has been paid to changes in physical activity. They focused on this area because inactivity can contribute to obesity, which raises the risk for joint failure and the need for revision procedures.

The team analyzed seven studies involving a total of 336 patients before and after joint replacement surgery. While all the studies showed patients’ pain and quality of life improved, most reported no increase in physical activity after six months and only a moderate rise after 12 months. Two studies did show an improvement, but the authors were unable to replicate those findings with the data provided. The results were published online in Arthritis Care & Research.

The researchers said the lack of activity likely stems from patients returning to their familiar pre-surgery sedentary lifestyle and that some had pain-related fear.

They recommended that physicians actively promote changes in physical activity and set goals for all patients undergoing knee or hip replacement. Their message: You have a new leg up on health, so get moving!