1. Prevention CfDCa Arthritis 2009 http://www.cdc.gov/nchs/fastats/arthrits.htm
2. Prevention CfDCa NHIS Arthritis Surveillance 2009 http://www.cdc.gov/arthritis/data_statistics/national_nhis.htm
3. Oral or transdermal opioids for osteoarthritis of the knee or hip (review);Nuesch;Cochrane Databse Syst Rev,2009
4. Burden of major musculoskeletal conditions;Wolf;Bull World Health Organ,2003