Summary of conclusions:
In the UK, I would say that chiropractic involves the most quackery with osteopathy a close second. Physiotherapy is significantly better than either of the others but there is still room for improvement.
This is an interesting question that was raised on Twitter. Answering this question may help members of the public decide whether to see a physiotherapist, chiropractor or osteopath.
What is “quackery”?
According to Wikipedia: “Quackery, often synonymous with health fraud, is the promotion of fraudulent or ignorant medical practices. A quack is a “fraudulent or ignorant pretender to medical skill” or “a person who pretends, professionally or publicly, to have skill, knowledge, qualification or credentials they do not possess; a charlatan or snake oil salesman”.”
It is often difficult to differentiate between those practices that are merely ignorant, where the practitioner believes they are helping, and fraudulent, where the practitioner knows they are deceiving their patients. Both definitely exist but it seems likely that more cases fit into the former category than the latter. In this situation, the practitioner has been so indoctrinated into the particular treatment approach that they believe they are helping even though the treatment they are using is unproven. This happens even in the most ridiculous treatment approaches such as homeopathy or reiki. It is important to understand that although the motivation of an ignorant practitioner is different to a fraudulent one; both present a risk to members of the public.
Quackery in the physiotherapy, chiropractic and osteopathy professions
As a starting point, I have previously highlighted some of the many issues with chiropractic and osteopathy professions in the UK: Now, this page could do with some updates as I have found even more issues with these professions since writing that. For instance, during the Covid-19 pandemic a number of UK chiropractors and osteopaths have made misleading claims about their treatments “boosting the immune system”.
As to physiotherapy, it is not free from the use of quackery. For instance, acupuncture is quite widely used within the physiotherapy profession (including on the NHS). Acupuncture lacks a plausible mechanism of action and has minimal evidence of effectiveness. However, is this really quackery at the same level as cranial osteopathy / craniosacral, treating “birth trauma”, treatment of asthma or autism and frequent breaches of advertising guidelines? I would suggest that it is not. The National Institute for Health and Care Excellence (NICE) included acupuncture in their draft guidelines for chronic pain. I have explained why I think this is wrong, but it is hard to blame an individual physio for using acupuncture when it is recommended by NICE. Chiropractors and osteopaths do use acupuncture too.
Treatment of babies
Treatment of babies is worryingly widespread within the chiropractic and osteopathy professions even though there is no evidence that these treatments provide any benefit for any infant health condition. See here, here, here and here for a few examples of misleading claims from chiropractors and osteopaths. This is just the tip of the iceberg as there are many other such claims that I have not yet had time to fully investigate.
I have previously tried to look for misleading claims from physios who treat babies and such claims are hard to find. Even though I was searching for physios, I found mostly osteopaths being returned from my searches.
Misleading advertising
Misleading advertising claims within the osteopathic and chiropractic professions has been a serious problem for many years. Although regulatory action, led by the Advertising Standards Authority, has resulted in some improvement it remains a significant issue. There are misleading claims from some physiotherapists too, although it appears to be a much less widespread issue. For instance, The Good Thinking Society have previously assessed the proportion of misleading advertising claims from physiotherapists, osteopaths and chiropractors. They found the chiropractors are the most likely to make misleading claims with osteopaths next and physios much less likely.
Conclusion
In the UK, I would say that chiropractic involves the most quackery with osteopathy a close second. Physiotherapy is significantly better than either of the others but there is still room for improvement.
Complementary and Alternative 