Hospitalizations for osteoarthritis more than doubled from 1993 to 2006, according to an analysis by the Agency for Healthcare Research and Quality.

Hospitalizations for the condition rose to 735,000 in 2006 from 322,000 in 1993. It was the principle diagnosis for about 90% of knee surgery hospitalizations and about half of hip replacement hospitalizations in 2006. Nursing homes are increasingly treating people who are recovering from such surgeries. The large increase in osteoarthritis hospitalizations is primarily related to the increase in knee replacement surgery, which increased 65% from 2000 to 20006. Hip replacement surgery increased 21%. Osteoarthritis is a painful condition resulting from deteriorating cartilage and bones rubbing together.

The analysis is based on data from the 2006 Nationwide Inpatient Sample, part of AHRQ’s Healthcare Cost and Utilization Project.