This paper has an extremely well referenced number of facts seemingly leading to one conclusion, that oddly appears to escape the authors. I think this paper was intended to be a pro-spinal manipulation review paper for physical therapists. However, unless there is some underlying satire I missed, I think they did a great job of debunking spinal manipulation. So if anyone is skeptical of my interpretations please be sure to read the article in whole for yourself and let me know if I missed anything.
Quoted from Section 3.2 on Segmental clinical decision making:
“This model is dependent upon accuracy in determining a dysfunctional vertebral motion segment; however, the literature suggests poor reliability of the assessment techniques. For example, poor to fair inter-rater reliability for spinal mobility testing has been observed (van et al., 2005; Seffinger et al., 2004) and these findings are not improved with training, experience or discipline (Seffinger et al., 2004; Billis et al., 2003). Additionally, the traditional clinical decision making approach necessitates the correction of a specific dysfunction with a specific technique; however, SMT is not specific to a given segment (Kulig et al., 2004; Lee and Evans, 1997). Specifically, the force of SMT is spread over multiple segments (Herzog et al., 2001) and the cavitation (or pop) frequently accompanying these interventions often occurs at segments other than the intended site (Ross et al., 2004). Furthermore, the chosen technique does not correspond to clinical outcomes. For example, clinical outcomes are similar for SMT of varying mechanical parameters (Cleland et al., 2009) and whether the specific SMT is determined by examination findings or randomly chosen (Chiradejnant et al., 2003).”
The above all sounds right on, and in my opinion it says everything. Spinal motion can not be reliably felt or tested for by palpation, more training doesn’t help, and even if it did it still doesn’t matter because spinal manipulation can not target a specific joint anyway. In fact, cracking the back using a technique opposite of what proponents think they need to correct perceived joint dysfunction “works” just as well. Full stop right there! In a paragraph they concisely and accurately took apart the whole charade. All they need now is a logical conclusion, but rather than coming to one they say:
“Collectively, these studies suggest a general biomechanical effect of SMT as opposed to an effect specific to a targeted segment.”
Biomechanical? Couldn’t it be psychological? I imagine there might be some afferent mild pain reduction due to weak exploitation of gate control theory, but a TENS machine lasts longer and a massage feels better.
Later in section 3.3 they talk about how spine manipulation researchers started to give up on treating specific joints and figured they would just try to figure out what type of person it does works for. Citing Timothy Flynn’s paper looking at clinical prediction rules for who responds to manipulation that blinded neither patient, nor therapist, nor evaluator and didn’t include a placebo or control group. And what did he find. Patients were more likely to respond favorably to spinal manipulation if they had the following 5 characteristics, the more they had being better.
- pain duration of less than 16 days
- fear avoidance beliefs work subscale score of less than 19
- hip internal rotation on one side of at least 35 degrees
- lumbar spine hypomobility
- pain not extending below the knee
The only variable that seems relevant, is (#4) lumbar hypomobility determined by a spring test, but didn’t the authors already cite research suggesting segmental testing results are unreliable? Otherwise, when I read the above prediction rules, it just sounds like people who get better with spinal manipulation are mostly people who only recently got low back pain that isn’t bothering them very much. These are exactly the kind of people I would expect to just get better anyway, regardless of how you treated them. The lack of true effect of spinal manipulation for acute low back pain was recently confirmed by researcher (and chiropractor who has manipulated a lot of spines) J. Michael Menke found when he ran the statistics on spinal manipulation, finding:
- “96% (81/84) of acute pain improvement in the first 6 weeks was unrelated to treatment”
- “Attention placebo nearly doubled the pB [probability of recovery] shown in the difference between attended and unattended physiotherapies…”
- “Acute pain treatment evidence never exceeded sham”
- “More research is not the answer. That which is already known about SMT for back pain is quantifiably all that is worth knowing.”
The inability spinal manipulation to beat out sham treatments for acute low back pain was also confirmed in the Cochrane review, again, with the main author being a chiropractor. So come on PTs, catch up!
Conclusion aside, I thought it was a great paper, but when you go into your physical therapy clinic, conclusion is everything. Much of the paper I couldn’t say better myself, but then the authors go on to talk about future directions, saying that more research is needed to understand the mechanisms through which spinal manipulation works, to which they all seem flabberghasted. Well, I have one idea that oddly wasn’t mentioned once in the paper…
- It starts with a “P”
- It rhymes with “lacebo”
That being, the positive benefits you all see with spinal manipulation, it’s in your head, and/or it’s in your patient’s head. It’s placebo effect! Barely propped up by poorly controlled studies and likely a fair degree of publication bias. Patient expectations likely are a factor, and it’s lot easier to sell a patient on ideas that make sense rather than some nebulous general effect. Section 3.1 about segmental treatment was good science, it made sense, and unfortunately clearly pointed away from spinal manipulation really fixing anything. If it went the other way, I’d be cracking spines.
As always, if you have any further questions or need for clarifications, please don’t hesitate to ask. Being aware that some of my blog ideas are contentious and occasionally a bit out of the field of my expertise, I encourage my readers to come forth with any questions/comments that are of interest or concern. Your comments are valued and welcomed.
Chad Reilly is a licensed physical therapist, located in North Phoenix, practicing science based medicine with treatment protocols unique and effective enough to proudly serve patients from Phoenix, Scottsdale, Mesa, Chandler, Tempe, Peoria, and Glendale.