There is strong evidence from a systematic review of a large number of RCTs, and subsequent RCTs, that for osteoarthritis of the knee, exercise reduces pain, disability, and medication intake, and improves physical functioning, stair climbing, walking distance, muscle strength, balance, self-efficacy, and mental health. A few studies suggest that exercise may be beneficial for people with osteoarthritis of the hand or hip (although the mechanisms may be different). There is no good evidence that one type of exercise is superior to any other type. Exercise delivered in a class and supplemented by exercise at home may be superior to home exercise alone, and appears to be cost effective. Two RCTs suggest that exercise in water may have short-term benefits. Adverse events were inconsistently studied, but the National Institute for Health and Clinical Excellence (NICE) consider the risk to be low if the suitability of the exercise for the individual is appropriately assessed by a trained healthcare professional.

Exercise may be targeted at individual joints, or at general fitness. It may be taken at home, or in a supervised class in which the instructor may lead a group or an individual. Exercise may be taken on land or in water. Exercise interventions include aerobic walking, quadriceps exercise, strengthening and home exercise, aerobic exercise with weight training, and diet with aerobic and resisted exercise.

NICE conducted a systematic review of the effects of exercise on osteoarthritis [National Collaborating Centre for Chronic Conditions, 2008].

• The review addressed two types of question:
• Is exercise more effective than no exercise or other treatments?
• Are the risks and benefits of one type of exercise preferable to those of other types of exercise?
• Different studies used a number of different interventions for people with differing types and severity of osteoarthritis and assessed the outcomes with a number of different measures over a range of follow-up times.
• Land-based exercise:
• Evidence on the first question was provided by 29 RCTs. Evidence on the second question was provided by nine RCTs.
• Osteoarthritis of the knee:
• Exercise reduced pain, disability, and medication intake, and improved physical functioning, stair climbing, walking distance, muscle strength, balance, self-efficacy, mental health, and physical functioning. The majority of these beneficial outcomes were seen at 18 months.
• Osteoarthritis of the hand or hip:
• A few studies provided inconclusive and/or indirect evidence of effectiveness.
• Economic analysis:
• NICE found four economic studies that met their review criteria.
• One well-conducted study provided evidence relevant to the UK. It found that supplementing a home-based exercise programme with a class-based programme is cost saving or cost effective. If travel costs were included, it is probable that the class-based supplement would still be cost effective.
• Adverse effects:
• No serious adverse effects of exercise were identified by NICE.
• Exercise in water (hydrotherapy/aquatic exercise):
• NICE found six RCTs that met their criteria for inclusion in the review.
• There is mixed, but mostly positive, evidence to suggest that exercise in water may be beneficial in the short term with respect to pain, stiffness, function/disability, muscle strength, and quality of life.
• Methodological weaknesses were commonly present in the studies, and included lack of blinding, flaws in randomization, small sample sizes, absence of power calculations, and no information on intention-to-treat analyses.
• Manual therapy:
• Manual therapies include joint manipulation, mobilization, and stretching, with or without exercise.
• Most studies evaluated manual therapy for osteoarthritis in combination with other treatment approaches, for example exercise. This reflects current practice in physiotherapy, where manual therapy would not be used as a sole treatment for osteoarthritis but as part of a package of care.
• Osteoarthritis of the hip:
• One RCT and one observational study provide evidence, consistent for a number of outcome measures, that manual therapy is more effective than exercise.
• Osteoarthritis of the knee:
• Seven studies provide mixed but mainly favourable evidence, for a number of outcome measures, that manual therapy is more effective than exercise.
• Adverse effects:
• No serious adverse effects of manual therapy were identified by NICE.
• Methodological weaknesses were commonly present in the studies, and included lack of blinding, flaws in randomization, small sample sizes, absence of power calculations, and no information on intention-to-treat analyses.