1. World Health Organization. The world health report. 50 facts. http://www.who.int/whr/1997/media_centre/50facts/en/ . Accessed 12 May 2014.
2. Moskowitz RW. The burden of osteoarthritis: clinical and quality-of-life issues. Am J Manag Care. 2009;15:S22–39.
3. Jordan J, Luta G, Renner J, Dragomir A, Hochberg M, Fryer J. Knee pain and knee osteoarthritis severity in self-reported task specific disability: the Johnston County Osteoarthritis Project. J Rheumatol. 1997;24:1344–9.
4. Hochberg MC, Altman RD, April KT, Benkhalti M, Guyatt G, McGowan J, et al. American College of Rheumatology. American College of Rheumatology 2012 recommendations for the use of nonpharmacologic and pharmacologic therapies in osteoarthritis of the hand, hip, and knee. Arthritis Care Res. 2012;64:465–74.
5. National Collaborating Centre for Chronic Conditions: Osteoarthritis: National clinical guideline for care and management in adults. London: Royal College of Physicians, 2008. http://www.nice.org.uk/guidance/cg59/resources/guidance-osteoarthritis-the-care-and-management-of-osteoarthritis-in-adults-pdf . Accessed 12 May 2014.