February 15, 2017

Do I chase the pop? Story of Manipulation

Author: Maggie Henjum


Ownership of manipulation is for a whole other post but it should be duly noted that manipulation of the spine has historically been performed by physical therapists since the 1920’s and we are the drivers of most manipulation related research.1 Unfortunately, this has not seemed to translate to public perception.  Although possibility of positive exposure should prevail as we continue to delve closer to defining its effects and usage in the clinic.

What is it?

Defining manipulation seems to be our first stop – although this proves to be quite challenging.  Some would debate that if we don’t understand its mechanism should we be using it – this seems short sighted to me. An engineering tool established the sound of a manipulation is developed from a growth and collapse of gas or vascular bubbles in liquid.2 That seems uncomplicated enough, so why are we all chasing after this effect?

Who benefits?

Manipulation of the lumbar spine wins a popularity contest; everyone wants to be friends with it.  It is a likable technique, it drives quick, and has notable positive effects on outcomes within the first session with reasonably low risk.  Basically, you get an optimistic response without the commitment.  Patients see instantaneous effects from this method as it positively influences their perceived function, pain and return to work status.

Dr Flynn leads us with some outstanding lumbar manipulation studies and most of them expose all people had reduction in the Oswestry after a lumbar spine manipulation – yet still we venture to find the perfect patient fit.15 Patients who meet the criteria of: symptom duration <16 days, symptoms above the knee, hypomobile lumbar spine, hip internal rotation (at least one hip and tested in prone) >35 degrees, and a low fear avoidance beliefs are our glory group.10 Four of the five of these factors can drive post probability of success from 45% to 95%.10 Even if a patient has 3 of the five factors,  he or she demonstrates a 68% success rate. For the primary care MD who does not have time to evaluate all of these criteria, he or she can still assess symptom duration and symptoms above the knee. Even these two diagnostic criteria are expected to have +LR = 7.2 with manipulation of the lumbar spine.9 For the unfamiliar – predictor of success is a 50% drop in of the Oswestry – now, that is a heavy hitter technique.10 This effect is largely seen immediately, but is held for 8 weeks and up to a year.13 We even see benefit in use with chronic patients for 8 weeks, and this reduced sick leave in the manipulation group, as only 19% of patients were sick-listed at 1-year follow-up compared to 59% in a exercise group.13

We have honed in on specificity of who is appropriate for this technique, but, conversely, who isn’t? The obvious limitations lie in patients with cancer, osteoporosis, etc. However,most studies exclude patients who have positive SLR, myotomal weakness, diminished DTR’s or absence to sensation, and these should be considered. 7 Although, relative risk is so low in the lumbar spine – the juice is still worth the squeeze.  Most common side effects are localized soreness, but only 1% reported worsening disability compared to the 11% who worsened with  exercise.14 Even when used on the “riskier” population of discogenic symptoms, patients were ½ as likely to have surgery with manipulation.15 In conclusion, even though we have developed the CPR to delineate who responds best to manipulation, this still may pigeon hole this technique as really the majority of studies show some advantage – even with the high risk population.

What does it do?

Again, this quick and easy technique demonstrates a significant and immediate drop in pain and improvement in function, but again why?  Neurophysiologic effects and some possible translation in mobility of the segment can be inferred.  Positive effects of manipulation seem to be clearly defined in numerous studies attempting to characterize its place in patient care.  Instantaneous effects on pain are shown to be from local dorsal horn mediated inhibition of C-fiber input, which could explain its potential hypoalgesic effect.3 Afferent response has been shown to vary based on the velocity and amplitude of the force applied – which would explain why outcomes with mobilization are sub-par to manipulation.7

Even recently we have inferred changes in the diffusion of H2O within the intervertebral discs in those who responded positively to manipulation possibly providing some explanation to benefit to this technique.11 Time will hopefully clearly define its mechanistic approach. In the meantime, supportive data defines that it should be utilized and as you can see only some research implies why.

Is this a self-fulfilling prophesy?

A pain PhyschD once told me, “Pain is relative to those who have it and the story is only as true as what we tell ourselves.” Which begs the question – who is driving the boat in these proposed success rates?

Most literature presented with Dr. Flynn demonstrates that we have no change in outcomes if a cavitation is heard or not heard.  We have data to show that even though most people have cavitation, it does not correlate with positive outcomes of this tool.12 Although, in most studies, there is a set up wherein manipulation is stopped either if a maximum attempt number was achieved, or if a therapist heard a cavitation.6 Therefore, what are we telling ourselves?  We can speculate that pre-conceived notions of outcomes by the therapist and patient directly affect outcomes.8 As we develop more research in this area – will this start shifting our understanding on what defines a “successful” manipulation?

Progressing this thought further – does patient perception give us these positive effects? In the lumbar spine, most people thought that strengthening and stretching would positively affect their outcomes not manipulation or manual techniques.  Although active interventions for the lumbar spine are positively received by patients.4 Contrarily, the cervical spine patients thought that massage and manipulation would positively affect outcomes over stretching and strengthening.5  This dichotomy is somewhat amusing as we have much stronger literature in the lumbar spine to manipulate compared to the neck. Although patient expectation and outcomes were strongly correlated in the cervical spine, this was not seen as significant in the lumbar spine.4 Regardless – the intervention is well received and we may see that as research develops this could drive outcomes. I do think this area of literature is underdeveloped and I hope to see it catch some steam in years to come on patient and therapist expectations and their effect on outcomes.


Original post: January 22, 2014



  1. Position on Thrust Joint Manipulation Provided by Physical Therapists. APTA. February 2009; 1-11.
  2. Tim Flynn. Do Pops and Technique Specificity Change Outcomes.  Lecture performed by EIM. January 14, 14.
  3. George S, Bishop M, Bialosky J, Zeppieri G, Robinson M. Immediate effects of spinal manipulation on thermal pain sensitivity: an experimental study. BMC Musculoskeletal Disorders 2006, 7:68.
  4. Mark D Bishop, Joel E Bialosky, and Josh A Cleland. Patient expectations of benefit from common interventions for low back pain and effects on outcome: secondary analysis of a clinical trial of manual therapy interventions. Journal of Manipulative Medicine. 2011; 19:20-25.
  5. Bishop M, Mintken P, Bialosky J, Cleland J. Patient Expectations of Beneift From Interventions For Neck Pain and Resulting Influence On Outcomes. JOSPT. 2013; 43: 457–465
  6. Cleland JA, Fritz JM, Kulig K, Davenport TE, Eberhart S, Magel J, Childs JD. 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: 2720-2730.
  7. Cleland JA, Fritz JM, Kulig K, Davenport TE, Eberhart S, Magel J, Childs JD. 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: 2720-2730.
  8. Cook C, Learman K, Showalter C, Kabbaz V, Bryan O’Halloran. Early Use of Thrust Manipulation Versus Non-Thrust Manipulation: A Randomized Clinical Trial. Manual Threapy. 2002: 1-8.
  9. Fritz JM, Childs J, Flynn T. Pragmatic application of a clinical prediction rule in primary care to identify patients with low back pain with a good prognosis following a brief spinal manipulation intervention. BMJ. 2005; 6: 29-37.
  10. Flynn T, Fritz J, Whitman J, Wainner R, Magel J, Rendeiro D, Butler B, Gaber M, Allison S. A Clinical Prediction Rule for Classifying Patients with Low Back Pain Who Demonstrate Short-Term Improvement With Spinal Manipulation. Spine 2002; 27: 2835-2843.
  11. Beattie P, Butts R, Donley J. The Within-Session Change in Low Back Pain Intensity Following Spinal Manipulative Therapy Is Related to Differences in Diffusion of Water in the Intervertebral Discs of the Upper Lumbar Spine and L5-S1. JOSPT. 2014; 44: 19-29.
  12. Flynn T, Fritz J, Wainner R, Whitman J. The Audible Pop Is Not Necessary for Successful Spinal High-Velocity Thrust Manipulation in Individuals With Low Back Pain. Arch Phys Med Rehabil. 2003.
  13. Ayre FO, Nilsen JH, Vasselijen O. Manual Therapy and Exercise Therapy in Patients with Chronic Low Back Pain. Spine. 2003; 28: 525-532.
  14. Childs J, Flynn T, Fritz J. A perspective for considering the risks and benefits of spinal manipulation in patients with low back pain. Manual Therapy. 2006; 11: 316-320.
  15. Tim Flynn. Management of LBP Who Responds to SMT.  Lecture performed by EIM. January 14, 14.