Osteoarthritis is a common disabling disorder increasing in prevalence with advancing age (Blixen and Kippes, 1999). As there is a rapid increase in the percentage of people over 55 years in Western countries (Okma-Keulen and Hopman-Rock, 2001) it has become increasingly important to address issues which relate to older people. In 2010, the projected percentage of the population aged 60 years or older in Europe will be approximately 25%. The increased incidence of arthritis among older people, which is a significant health care problem today, is set to become an even greater concern in the coming years (Reginster, 2002). Rheumatic diseases are a huge encumbrance on the health care systems of countries worldwide and account for significant disability, lost productivity and reduction in quality of life (Sangha, 2000). The burden of disease relates not only to its prevalence but also to the cost of the disease to the health care system of the country, these costs include direct costs, such as the costs associated with drugs, medical care, hospitals, research, pensions and benefits and indirect costs, such as premature mortality and chronic disability (Reginster, 2002). Neither census statistics nor statistics from the Department of Health and Children revealed the true prevalence of osteoarthritis in Ireland. A search was also carried out using the Hospital Inpatient Enquiry (HIPE) system of The Economic and Social Research Institute of Ireland (ESRI) which likewise did not reveal the frequency of osteoarthritis in the population.

Osteoarthritis is characterised by progressive loss of articular cartilage, appositional subchondral bone development and osteophyte formation at the joint margins. The resulting pain, stiffness and functional limitations (Jakobsson and Hallberb, 2002) lead to diminished quality of life. The knee is a particularly common site of involvement in osteoarthritis. Osteoarthritic knee pain has been found to be associated with poor perceived health and significant disability, while psychological distress strongly associates with both pain and disability (O'Reilly et al, 1998; Sangha, 2000). Restricted knee joint mobility, in particular flexion appears to be an important determinant of disability in patients with osteoarthritis (Steultjens et al, 2000). Minor et al (1999) noted that lower extremity impairments in older adults have been linked to the reduced ability to use public transportation, climb stairs, perform household chores, shop and engage in leisure activities. Similarly van Barr (1998) noted that disability in patients with lower limb osteoarthritis is significantly related to pain and joint range of motion. Due to the chronic nature of osteoarthritis, physical modalities, lifestyle modification and patient self-management in terms of education and exercise are considered important approaches to treatment (Sangha, 2000).

Physiotherapists have an important role to play in the clinical management of osteoarthritis (Green et al, 1993) however, the effect of their involvement has rarely been assessed in terms of randomised controlled trials. Chard et al (2000) examined the research output in relation to a number of physiotherapy interventions available to patients with osteoarthritis of their knees and established that between 1950 to 1998 only 60 research articles were published, the majority of which occurred between 1985 and 1998. Advice (Maurer et al, 1999; Manek and Lane, 2000) and exercise (Puett and Griffin, 1994; Clarke, 1999; O'Reilly et al, 1999) have been clearly identified as beneficial in terms of relieving the impairments experienced by individuals with knee osteoarthritis. Indeed there is a some evidence supporting the use of a number of physiotherapy interventions including hydrotherapy (Ahern et al, 1995; Norton et al 1997; Alexander et al, 2001) and continuous short-wave diathermy (CSWD) (Wright, 1964; Lankhorst et al, 1982) for the treatment of knee osteoarthritis but there are difficulties regarding the design of many of these studies thus undermining the conclusions that have been drawn. This study presents the results of a randomised controlled factorial trial (Polger and Thomas, 2000) designed to examine hydrotherapy and/or continuous short wave diathermy (CSWD) for patients with knee osteoarthritis while also examining the perceptions of patients participating in a physiotherapy programme.