Review: exercise interventions improve pain and function in people with knee osteoarthritis compared with no exercise
- 1University of Melbourne, Parkville, Victoria, Australia;
- 2Department of Physiotherapy, Centre for Health, Exercise and Sports Medicine, University of Melbourne, Parkville, Victoria, Australia
- Correspondence to: Professor Kim Bennell, Department of Physiotherapy, Centre for Health, Exercise and Sports Medicine, Level 7 Room: 707, Alan Gilbert Building, 161 Barry Street, The University of Melbourne, Parkville, Victoria 3010, Australia;
Implications for practice and research
Conclusive evidence has established the overall benefits of exercise in patients with lower limb osteoarthritis (OA).
Although there are no distinct differences in the benefit estimates of different types of exercises, those designed to improve strength, flexibility and aerobic capacity seem to provide the most benefit to patients with lower limb OA.
Therapeutic exercise is an integral component of conservative OA management and is universally recommended by current clinical guidelines.1–3 However, when it comes to choosing which types of exercises are best, the evidence is limited and inconclusive. The review by Uthman and colleagues focused on this research gap, comparing the effectiveness of different exercise interventions for improving pain and physical function in patients with lower limb OA, using both direct evidence (comparing treatments within the same trial) and indirect evidence (comparing treatments across trials). Additionally, the authors explored the question of whether sufficient evidence has been accumulated to definitively conclude that exercise interventions are more effective than no exercise.
A highly sensitive search strategy was used to maximise trial identification. Primary outcome measures of the treatment effects for patient-perceived pain and physical function change scores were estimated. Trial sequential analysis was used to examine the reliability and conclusiveness of the available evidence, while a random effects network meta-analysis was used to compare the benefits of different exercise interventions. Exercise approaches were then ranked according to the most effective combinations.
This review included 60 separate trials (44 knee, 2 hip, 14 mixed) covering 12 different exercise combinations. The overall improvement in pain, compared with control, was largest for strengthening exercises, where a mean change of −2.03 cm, on a 10 cm visual analogue scale, was estimated. Strengthening exercises were ranked as the second best approach, closely behind an approach of aquatic-strengthening-plus-aerobic-flexibility. The overall improvement for physical function was largest for a strengthening-plus-flexibility-plus-aerobic-exercise approach, where a mean change of −1.32 units, on a transformed 10-point western Ontario and McMaster Universities scale, was estimated. This combined approach was ranked as equal best, along with aquatic-strengthening-plus-aerobic-exercise.
This systematic review focused on clarifying which types of exercise provide the best benefits for pain and physical function. Further, a trial sequential analysis was used to determine if and when sufficient evidence for exercise had been accumulated. Results showed that, as of 2002, sufficient evidence had been accrued to demonstrate an overall benefit of exercise over no exercise. Further trials are unlikely to overturn this finding. However, given that the majority of studies involve knee OA, further research is needed to conclusively demonstrate this for hip OA.
Although several systematic reviews in similar populations have been published, these have predominantly focused on pairwise comparisons of different exercise interventions within individual trials. In this review, both within-trial and across-trial evidence was synthesised and network meta-analysis was performed to help tease out which type of exercises are best. Similarly to previous findings, there was no significant difference between exercise types.4 However, cumulative ranking showed both land-based and water-based interventions combining strengthening with flexibility and aerobic exercise seemed to provide the best benefits. Importantly, overall change scores estimated for pain and function following these approaches were greater than reported minimum clinically important change,5 indicating that the benefits appeared to be meaningful.
An importance of this study is that it reinforces further research directions. As treatment benefits of the exercise types are mostly small to medium, there is a need to further identify whether different subgroups of patients respond differently to different types of exercise approaches, and to explore the optimal dosages of different exercise programmes. As conclusive superiority of one exercise programme over the other remains unclear, the type and dosage of exercise should be individualised to the patient and informed by patient preferences.