One of the ways in which this is the case is our approach to the nature of pain and injury.
We have been moving away from the idea that "the issue is in the tissue" (i.e. you have a damaged [insert structure here] that is causing your pain), and more towards an understanding that, well, things are rarely that simple! This puts more emphasis on 'command and control', and recognises that pain is multifactorial, that is, influenced by lots of different things. This poses a problem for the study and treatment of these issues.
For example, there is a difference between an osteopathic technique, which is a particular intervention e.g. manipulation of the L4/5 spinal segment (part of your spine, in the low back area); and osteopathic treatment, which refers to the entire encounter with the osteopath, and will likely include many different techniques/approaches.
As osteopathy is an 'holistic' discipline (it tries to treat the whole body/person rather than just the bit that hurts), you might treat someone with a painful/restricted L4/5 [region of the spine] with the aforementioned manipulative technique. However, in patient A this is combined with work through the mid and upper back region, and in patient B, with the pelvis and legs.
Doing an experiment to find out how helpful that L4/5 manipulation is, then, does not take into account the effect of the work above (with Patient A) or below (with Patient B) the painful areas.
And even in the same patient, at various stages in treatment, different areas might be assessed as being more or less relevant.
When these studies are being done, they obviously want to make sure there is nothing else going on that might cause the pain, so will often use MRI or X-Ray (both ways of looking at what is going on inside the body) scans. If there is nothing obviously causing the patient's symptoms, it will be lumped under the category 'non-specific low back pain'. However, there will be lots of factors that are not the same between these patients - "always remember you're unique - just like everyone else!" - and thus the useful information we can get from these studies is even smaller.
HOWEVER, we do have quite a few studies from the last few decades that can tell us a little about how people get better after hurting themselves, and what helps (and doesn't!).
As an ethical osteopath, I obviously want to use the best methods to help my patients get back to their lives. But the problem is, if I only go on the evidence, and only do things that are proven to work, I would not do much!
This is because much of what we treat does not have a good evidence base. This does not mean it does not work (millions of happy patients would argue otherwise!), but that the research is not there either way (for many reasons, some of which are described above).
So this blog post will end with one phrase familiar to any readers of scientific literature: "more research is required"; but with an addendum: "in the areas we can research effectively"