Moderators of the effect of therapeutic exercise for knee and hip osteoarthritis: a systematic review and individual participant data meta-analysis
Three pages on PainSci cite Holden 2023: 1. Bone on Bone 2. Bone-on-bone, Part 2: Should we ever say it? (Member Post) 3. Exercise for arthritis is underwhelming
PainSci commentary on Holden 2023: ?This page is one of thousands in the PainScience.com bibliography. It is not a general article: it is focused on a single scientific paper, and it may provide only just enough context for the summary to make sense. Links to other papers and more general information are provided wherever possible.
This is a 2023 review of mostly the same data as past reviews of exercise for hip and knee osteoarthritis … but this one's fancier, and maybe more valuable than the rest of them put together. It’s an analysis of “individual patient data,” which is a more hardcore kind of meta-analysis. Instead of studying the pooled results of trials, they get the original data and started from scratch. It’s a lot of work, and Melanie Holden and fifty-three colleagues did the IPD thing for 4200 participants in 31 trials.
The results seem nice at first, highlighting a “positive overall effect of therapeutic exercise on pain and physical function in individuals with knee or hip osteoarthritis, compared with non-exercise controls.” Sounds familiar.
But it’s a small effect. Very small.
“This effect is of questionable clinical importance, particularly in the medium and long term.”
And that’s the news here. They concluded that exercise moved the needle just 6 points on a 100-point pain scale (on average). That’s much less than what people can even detect! And you cannot care about what you can’t feel.
And then it got worse beyond three months. 😬
We’ve always known exercise for arthritis delivered only a modest benefit, but there have been ominous signs that even that much may have been overestimated. For instance, a clever 2022 trial that found that it was no better than a placebo. And now this!
But it’s worth emphasizing that the benefit is almost certainly real, albeit small, and it’s an average, so some people will do better. And there are still many other benefits to exercise, of course.
original abstract †Abstracts here may not perfectly match originals, for a variety of technical and practical reasons. Some abstacts are truncated for my purposes here, if they are particularly long-winded and unhelpful. I occasionally add clarifying notes. And I make some minor corrections.
BACKGROUND: Many international clinical guidelines recommend therapeutic exercise as a core treatment for knee and hip osteoarthritis. We aimed to identify individual patient-level moderators of the effect of therapeutic exercise for reducing pain and improving physical function in people with knee osteoarthritis, hip osteoarthritis, or both.
METHODS: We did a systematic review and individual participant data (IPD) meta-analysis of randomised controlled trials comparing therapeutic exercise with non-exercise controls in people with knee osteoathritis, hip osteoarthritis, or both. We searched ten databases from March 1, 2012, to Feb 25, 2019, for randomised controlled trials comparing the effects of exercise with non-exercise or other exercise controls on pain and physical function outcomes among people with knee osteoarthritis, hip osteoarthritis, or both. IPD were requested from leads of all eligible randomised controlled trials. 12 potential moderators of interest were explored to ascertain whether they were associated with short-term (12 weeks), medium-term (6 months), and long-term (12 months) effects of exercise on self-reported pain and physical function, in comparison with non-exercise controls. Overall intervention effects were also summarised. This study is prospectively registered on PROSPERO (CRD42017054049).
FINDINGS: Of 91 eligible randomised controlled trials that compared exercise with non-exercise controls, IPD from 31 randomised controlled trials (n=4241 participants) were included in the meta-analysis. Randomised controlled trials included participants with knee osteoarthritis (18 [58%] of 31 trials), hip osteoarthritis (six [19%]), or both (seven [23%]) and tested heterogeneous exercise interventions versus heterogeneous non-exercise controls, with variable risk of bias. Summary meta-analysis results showed that, on average, compared with non-exercise controls, therapeutic exercise reduced pain on a standardised 0-100 scale (with 100 corresponding to worst pain), with a difference of -6·36 points (95% CI -8·45 to -4·27, borrowing of strength [BoS] 10·3%, between-study variance [τ2] 21·6) in the short term, -3·77 points (-5·97 to -1·57, BoS 30·0%, τ2 14·4) in the medium term, and -3·43 points (-5·18 to -1·69, BoS 31·7%, τ2 4·5) in the long term. Therapeutic exercise also improved physical function on a standardised 0-100 scale (with 100 corresponding to worst physical function), with a difference of -4·46 points in the short term (95% CI -5·95 to -2·98, BoS 10·5%, τ2 10·1), -2·71 points in the medium term (-4·63 to -0·78, BoS 33·6%, τ2 11·9), and -3·39 points in the long term (-4·97 to -1·81, BoS 34·1%, τ2 6·4). Baseline pain and physical function moderated the effect of exercise on pain and physical function outcomes. Those with higher self-reported pain and physical function scores at baseline (ie, poorer physical function) generally benefited more than those with lower self-reported pain and physical function scores at baseline, with the evidence most certain in the short term (12 weeks).
INTERPRETATION: There was evidence of a small, positive overall effect of therapeutic exercise on pain and physical function compared with non-exercise controls. However, this effect is of questionable clinical importance, particularly in the medium and long term. As individuals with higher pain severity and poorer physical function at baseline benefited more than those with lower pain severity and better physical function at baseline, targeting individuals with higher levels of osteoarthritis-related pain and disability for therapeutic exercise might be of merit.
FUNDING: Chartered Society of Physiotherapy Charitable Trust and the National Institute for Health and Care Research.
related content
- “Exercise and education versus saline injections for knee osteoarthritis: a randomised controlled equivalence trial,” Bandak et al, Annals of the Rheumatic Diseases, 2022.
- “Exercise and education vs intra-articular saline for knee osteoarthritis: a 1-year follow-up of a randomized trial,” Henriksen et al, Osteoarthritis Cartilage, 2023.
- “Comparative efficacy of exercise therapy and oral non-steroidal anti-inflammatory drugs and paracetamol for knee or hip osteoarthritis: a network meta-analysis of randomised controlled trials,” Weng et al, British Journal of Sports Medicine, 2023.
- “Exercise for osteoarthritis of the knee: a Cochrane systematic review,” Fransen et al, British Journal of Sports Medicine, 2015.
- Bone on Bone — How often are those dirty words about arthritis a harmful exaggeration? And should we ever use them, even when it’s accurate?
Specifically regarding Holden 2023:
This page is part of the PainScience BIBLIOGRAPHY, which contains plain language summaries of thousands of scientific papers & others sources. It’s like a highly specialized blog. A few highlights:
- Placebo analgesia in physical and psychological interventions: Systematic review and meta-analysis of three-armed trials. Hohenschurz-Schmidt 2024 Eur J Pain.
- Recovery trajectories in common musculoskeletal complaints by diagnosis contra prognostic phenotypes. Aasdahl 2021 BMC Musculoskelet Disord.
- Cannabidiol (CBD) products for pain: ineffective, expensive, and with potential harms. Moore 2023 J Pain.
- Moderators of the effect of therapeutic exercise for knee and hip osteoarthritis: a systematic review and individual participant data meta-analysis. Holden 2023 The Lancet Rheumatology.
- Inciting events associated with lumbar disc herniation. Suri 2010 Spine J.