Here is a review to a recent study on MDT. It examined whether pain responses to movement or position were linked to types of disc lesions.
Ironically, it found that patients with extruded discs and a certain lack of intra-discal pressure centralized better than those with normal or protruded discs with normal intra-discal pressure.
Despite the continuing mechanistic explanations (or lack thereof) for why MDT works, it just does. It's troubling to me that the biopsychosocial only approach does not bother to fix a patient's posture. Is is true that plenty of people slouch without pain or peripheralization; however, once they actually have symptoms, it is such an easy treatment, that often leads to immediate chances in increased ROM, decreased and centralized pain, absent reflexes sometimes return, strength tests increase, why wouldn't you start with correcting someone's posture? Think of it as a quick way to decrease CNS with education!
Whether the repeated end range loading bombards the CNS with proprioceptive input, thus decreasing a perceived threat and increasing movement tolerance, or the hydration of the annulus and position of a nucleus is changed, it works! Maybe it's both, or maybe it's neither. Anyone who has used MDT with success could tell you countless cases where going to end range was the ONLY way someone started responding. Possibly, the mechanoreceptors provide more input when pushed to end range?
Recent studies show that MDT had superior outcomes to thrust manipulation approach in the long term for 1 year follow up. Personally, I am waiting for a multi-modal study on MDT plus OMPT plus education with long term outcomes. Based on experience, I am sure that will have better outcomes than a manipulation alone < a book < education alone < exercise alone. I listed manipulation as the least effective because recent temporal studies show the effects of one mobilization lasting 5 minutes, and up to 24 hours for pain. The reason why the MDT approach works better in the long term is because the patients are constantly self mobilizing. So whatever the mechanism behind the improvement, it works because of the repetition and education.
An excellent PT visit is more than just one type of treatment, it is an experience in patient/clinician interaction, education, movement, and a combination of what works clinically and then by evidence. Someone recently worded it well, so I will paraphrase it, we cannot discount practice based evidence. Restricting your practice to following only the evidence will limit your patient outcomes as much as it helps them.