A negative trial of exercise for knee arthritis, with clever use of saline injection as a sham

PainSci » bibliography » Bandak et al 2022
updated Sep 9, 2024

Tags: exercise, arthritis, bad news, placebo, self-treatment, treatment, aging, pain problems, mind

Two pages on PainSci cite Bandak 2022: 1. Nitpicks galore! Four gripes about the exercise-versus-saline study (and four responses) 2. Not a good day for exercise-as-medicine

PainSci commentary on Bandak 2022: ?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 study of exercise for knee arthritis was clever about comparing to a placebo, which is always a challenge with exercise trials. They used a kind of “hack” to use saline injections as a good control for exercise.

Saline injections are obviously a fine sham when comparing to a medicinal injection. The recipient has no idea! But injections are very different from exercise. So the goal is to get to “equipoise” despite the difference, meaning that everyone involved has to take both treatments seriously, for whatever reason. In this case, saline can be taken seriously not as a “sham” — no one is going to mistake it for exercise! — but because it has credible effects on knee pain (via the placebo effect) as established in other kinds of trials.

Bit of a brain teaser, but a valid trial design.

And there was no difference! Exercise was not significantly better than saline injections. Journal Watch:

“That doesn’t necessarily mean that we should totally abandon exercise interventions, for at least two reasons: First, average outcomes in clinical trials sometimes obscure benefits for individuals. Second, for some patients, exercise might confer general well-being that isn’t easily measured.”

But yeah… really not a great result for exercise for the arthritic knee.

~ Paul Ingraham

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.

OBJECTIVE: To compare the efficacy of an exercise and education programme with open-label placebo given as intra-articular injections of inert saline on pain and function in individuals with knee osteoarthritis (OA).

METHODS: In this open-label, randomised controlled trial, we recruited adults aged ≥50 years with symptomatic and radiographically confirmed knee OA in Denmark. Participants were randomised 1:1 to undergo an 8-week exercise and education programme or four intra-articular saline injections over 8 weeks. Primary outcome was change from baseline to week 9 in the Knee Injury and Osteoarthritis Outcome Score (KOOS) questionnaire pain subscale (range 0 (worst)-100 (best)). Prespecified equivalence margins of ±8 KOOS pain points were chosen for the demonstration of comparable efficacy. Key secondary outcomes were the KOOS function and quality of life subscales, and patients' global assessment of disease impact.

RESULTS: 206 adults were randomly assigned: 102 to exercise and education and 104 to intra-articular saline injections. For the primary outcome, the least squares mean changes in KOOS pain were 10.0 for exercise and education and 7.3 for saline injections (difference 2.7 points, 95% CI -0.6 to 6.0; test for equivalence p=0.0008). All group differences in the key secondary outcomes respected the predefined equivalence margins. Adverse events and serious adverse events were similar in the two groups.

CONCLUSION: In individuals with knee OA, an 8-week exercise and education programme provided efficacy for symptomatic and functional improvements equivalent to that of four open-label intra-articular saline injections over 8 weeks.

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.

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