A lot of people find the sound or feeling of having their neck or back "cracked" or "popped" very satisfying. But what's actually happening? What does this actually do for you?
There are many healthcare professionals that perform some form of spinal manipulation, from osteopathic physicians, physical therapists, chiropractors, etc. Early in its history, the thought or notion was that bones and joints are not appropriately aligned and that manipulation might "reset" this. However, the vast preponderance of research suggests that "alignment" in this context isn't the end-all, be-all, and we don't have too much consistent evidence to show that bones truly move or are positioned differently after the technique[1,2]. Nevertheless, a lot of people (patients and providers alike) find the techniques helpful, and certainly there is research to support its use in helping address pain. So, what is happening?
Topic #2: Where has research shown spinal manipulation to be of benefit?
The response of the nervous system
For those that like to know the "why" of something, here's what we have consistently seen in research. High-velocity (i.e., "thrust") manipulation techniques have an effect on how the nervous system processes information[3-7]. These changes have not shown to be permanent, but they certainly appear to have some effect. The best analogy I can offer is that of a dimmer switch – if a certain amount of pressure or a certain thermal stimulus yields a particular rating of pain, thrust techniques appear to make that same stimulus relatively less painful after a thrust manipulation.
Where has research shown spinal manipulation to be of benefit?
As with virtually everything in medically-oriented research, the data is mixed. However, there have been several studies exploring the role spinal manipulation has in reducing pain and improving function. The biggest thing to keep in mind here – most of these studies explore the use of spinal manipulation with other interventions. Many studies that solely look at manipulation aren't all that impressive, which underscores the importance of other modes of management (like activity modification, progressive exercise, and motor retraining/neuromuscular re-education).
Regardless, we've seen several studies published demonstrating the use of cervical and thoracic manipulation to help with things like mechanical neck pain(8), certain types of headaches[9], certain types of shoulder pain[10-11], and tennis elbow (i.e., lateral epicondylalgia)[12]. With acute-onset low back pain, several studies have been published showing benefit with early reductions in pain and improvement in function[13], and there is some literature supporting its use even with more persistent pain[14].
Why shouldn't I have my spine manipulated?
While these techniques are generally quite safe, there are instances where these techniques shouldn't be utilized. This is where seeing a provider that's well versed in medical screening and that understands the existing research is quite important. Adverse events are fairly uncommon with manipulation, but they can still happen. However, some quality studies examining these adverse events have demonstrated that often times there were signs in a patient history that indicated another pathway should have been sought for symptom management[15]. The good news, even if you fall into the category of those that shouldn't have this done, is that there are other conservative options for managing your symptoms. Seeking out providers that aim to understand you and what you've been experiencing and that understand where the research stands should afford you a situation where multiple treatment options are available to help you on your way to feeling better.
References:
1. Vernon H. Historical overview and update on subluxation theories. J Chiroprac Humanities. 2010;17:22-32.
2. Keating JC, et al. Subluxation: Dogma or science? Chiropr Osteopat. 2005;13(17): doi:10.1186/1746-13-17.
3. Bialosky JE, et al. Unraveling the mechanisms of manual therapy: Modeling an approach. J Orthop Sports Phys Ther. 2018;48(1):8-18.
4. Coronado RA, et al. Changes in pain sensitivity following spinal manipulation: A systematic review and meta-analysis. J Electromyogr Kinesiol. 2012;22(5):752-767.
5. Coronado RA, et al. The comparative effects of spinal and peripheral thrust manipulation and exercise on pain sensitivity and the relation to clinical outcome: A mechanistic trial using a shoulder pain model. J Orthop Sports Phys Ther. 2015;45(4):252-264.
6. Bishop MD, et al. What effect can manual therapy have on a patient's pain experience? Pain Manag. 2015;5(6):455-464.
7. George SZ, et al. Immediate effects of spinal manipulation on thermal pain sensitivity: An experimental study. BMC Musculoskel Disorders. 2006;7(68):https://doi.org/10.1186/1471-2474-7-68.
8. Puentedura EJ, et al. Development of a clinical prediction rule to identify patients with neck pain likely to benefit from thrust joint manipulation to the cervical spine. J Orthop Sports Phys Ther. 2012;42(7):577-592.
9. Haas M, et al. Dose-response and efficacy of spinal manipulation for chronic cervicogenic headache: A pilot randomized controlled trial. Spine J. 2010;10(2):117-128.
10. Peek AL, et al. Thoracic manual therapy in the management of non-specific shoulder pain: A systematic review. J Manual Manipulative Ther. 2015;23(4):176-187.
11. Mintken PE, et al. Some factors predict successful short-term outcomes in individuals with shoulder pain receiving cervicothoracic manipulation: A single-arm trial. Phys Ther. 2010;90(1):26-42.
12. Fernández-Carnero J, et al. Immediate hypoalgesic and motor effects after a single cervical spine manipulation in subjects with lateral epicondylalgia. J Manipulative Physiol Therapeutics. 2008;31(9):675-681.
13. Cleland JA, et al. Comparison of the effectiveness of three manual physical therapy techniques in a subgroup of patients with low back pain who satisfy a clinical prediction rule. Spine. 2009;34(25):2720-2729.
14. Coulter ID, et al. Manipulation and mobilization for treating chronic low back pain: A systematic review and meta-analysis. Spine J. 2018;18:866-879.
15. Puentedura EJ, et al. Safety of cervical spine manipulation: Are adverse events preventable and are manipulations being performed appropriately? A review of 134 case reports. J Manual Manipulative Ther. 2012;20(2):66-74.