Are Diagnostic Paradigms Based on Scientific Thought and Procedure?

In an editorial titled “Science or Cult?” published in PTJ in 1963, Hislop stated, “Observations are the principal data of clinical science. Sometimes observations are inaccurate and faulty. Inferences and concepts can arise from such observations which also may be indefinite and confused. For persons not well grounded in scientific thought and procedure, this kind of muddled thinking can result in the indefensible error of offering explanation and rationalization of undocumented and unproved theory.”¹

• What are our diagnostic paradigms?
• Are diagnostic paradigms based on scientific thought and procedure?
• Are we rationalizing the use of unproven theories in the diagnosis of musculoskeletal disorders?

Sean P. Riley, PT, DPT, ScD

Twitter @seanrileypt

Assistant Professor, Doctor of Physical Therapy Program, University of Hartford, West Hartford, CT. 06117

Competing interests: Center of Excellence in Manual and Manipulative Therapy at Duke University.

What are the diagnostic paradigms?

Diagnostic classifications such as the International Classification of Diseases (ICD) and International Classification of Functioning, Disability, and Health (ICF) are based on the validity of the pathoanatomic model as the cause of the patient’s symptomatic complaints and impairments. Movement-based classifications (MBC) have been described as including Mechanical Diagnosis and Treatment (MDT), Treatment Based Classification (TBC), Pathoanatomic Based Classification (PBC), Movement System Impairment Syndromes (MSI), and the O’Sullivan Classification System (OCS).² Some of these classifications are based on a pathoanatomic gold standard and assume a bidirectional cause and effect relationship between pathology and movement.³

Are diagnostic paradigms based on scientific thought and procedure?

Many diagnostic paradigms are based on a pathoanatomic gold standard, such as the ICD, ICF, PBC, and MSI. These classifications are based on the validity of the pathoanatomic gold standard as the “cause” or a “contributing factor” of a patient’s primary symptomatic complaint and neuromusculoskeletal impairments.³ These models also suggest that movement causes pathoanatomic changes (kinesiopathologic) and pathoanatomic changes (pathokinesiological) cause musculoskeletal impairments and aberrant movements.³

The unfortunate truth is that there is a high prevalence of pathoanatomic findings in asymptomatic individuals. The prevalence of asymptomatic pathoanatomic MRI findings by region that varies based on diagnosis are neck 58-87%, shoulder 52%-88%, low back 20%-88%, Hip 12%-69%, knee 43%-97%, ankle and foot 27%-68%.⁴ Additional challenges related to movement-based classifications are reliability, patients not fitting into any category, and patients fitting into more than one category.⁵ Surgery that corrects pathoanatomy has similar clinical outcomes as conservative care. Finally, clinical outcomes are no better than general exercise and guideline-based care when using movement-based classification paradigms to treat patients.⁵

This reality has moved us into pain mechanisms, including nociceptive, peripheral neuropathic (radicular or referred), and nociplastic.⁶ Nociplastic symptoms are present in the absence of any pathological findings in patients with chronic low back pain with a prevalence of 13% to 78% across three studies.⁷ This suggests that diagnostic systems based on this pathonatomy directly conflict with pain neuroscience. Although promising, pain mechanism diagnostic criteria have not been prospectively validated. Attempts at validation suggest small changes in posttest probability with large confidence intervals for the nociplastic diagnosis.⁸ Pain phenotyping applied through an algorithmic classification suggests a pain mechanism is this, that, or the other thing.⁹ For a diagnosis to be clinically useful in musculoskeletal manual physiotherapy, it must reliably create subgroups of patients with symptoms, have clear and measurable differences between these patients, must be able to classify all patients, and should not have diagnoses that patients rarely or never fit into.¹⁰

“Sixty percent of the time it works every time.” – Brian Fantana

Are we rationalizing the use of unproven theories in the diagnosis of musculoskeletal disorders?

The problem with the diagnosis paradigm is that it is not universally applicable to all patients in what should be a patient-centered model. The diagnostic and classification paradigms’ primary challenge is that they use static labels to establish prognosis and direct treatment. An individual’s recovery should be dynamic if they improve within and between treatment sessions. Suppose the differential diagnosis and classification paradigms are valid. How do we rationalize a patient’s diagnosis or classification changing within a treatment session in response to an intervention?

Identifying if the patient’s primary symptoms are modifiable through mechanical input using manual therapy and/or exercise may be a powerful clinical reasoning tool. If the patient’s dominant symptoms are nociplastic, they are not modifiable, and the focus should be on function without worsening their primary symptoms. In this context, a win is framed to the patient as a progressive increase in function without worsening symptoms. We should probably avoid external mechanical or chemical inputs for most of these individuals as they will not likely change these centrally mediated symptoms. If the symptoms are modifiable, they are likely nociceptive or peripheral neuropathic. But, as you address the dominant pain mechanism, another may become dominant. For example, you may have somebody with primary peripheral neuropathic symptoms. Those symptoms resolve, and the predominant symptoms are now nociceptive; you address those, and their symptoms stabilize (say 2-3/10) and don’t change further. They have likely become nociplastic dominant, and function should be progressed without increasing the patient’s symptoms.

Beyond the mechanism of why the patients have their symptoms, where the mechanical input is applied may be essential and change during recovery. How the mechanical input is used through load, position, and tension is likely also essential and may change during recovery. The dynamic changes in the why (pain mechanism), where (location), and how the mechanical input is applied may be necessary during recovery. It is also essential to recognize that when and if the symptoms are not modifiable, there should be a focus on function without making mechanical (immediate) or potentially delayed (inflammatory) nociceptive symptoms worse.

It may be time to move beyond naming the problem to a reasoned approach that identifies the most efficient way to address the issue through probabilistic bayesian reasoning.¹¹ If we can identify the mechanism of why the patient has their symptoms, where the symptoms are most likely coming from, and how the mechanical input affects the neurophysiologic output, we may be able to modify these variables within and between treatment sessions to provide the best patient-centered approach probabilistically.¹² We, however, must ensure that what we see is not “…indefensible error of offering explanation and rationalization of undocumented and unproved theory.” ¹

Key Points

• Physical therapy is a science based profession that starts with observation
• Scientific thought turns observations into hypotheses that are tested using prospective procedures
• If the prospective procedures do not support the hypothesis it is time to develop a new hypothesis
• Science does not go through the prospective procedure and only recognize what fits and rationalize what doesn’t

Author bio(s): Sean Riley is an assistant professor at the University of Hartford, a clinical researcher, a physical therapist, and an advocate for the creation of ‘trustworthy’ research for the practicing clinician. He is board-certified in Orthopedics through the American Board of Physical Therapy Specialties and is fellowship-trained through the American Academy of Orthopaedic Manual Physical Therapists. He has 23 published manuscripts since 2015 and has presented his research at the national level each of the last eight years. Sean is also an Associate Editor for the Journal of Manual and Manipulative Therapy.

Bibliography

1. Hislop HJ. Science or cult? J Am Phys Ther Assoc. Mar 1963;43:163. doi:10.1093/ptj/43.3.163
2. Karayannis NV, Jull GA, Hodges PW. Physiotherapy movement based classification approaches to low back pain: comparison of subgroups through review and developer/expert survey. BMC Musculoskelet Disord. Feb 20 2012;13:24. doi:10.1186/1471-2474-13-24
3. Sahrmann S. Defining Our Diagnostic Labels Will Help Define Our Movement Expertise and Guide Our Next 100 Years. Phys Ther. Jan 4 2021;101(1)doi:10.1093/ptj/pzaa196
4. Sajid IM, Parkunan A, Frost K. Unintended consequences: quantifying the benefits, iatrogenic harms and downstream cascade costs of musculoskeletal MRI in UK primary care. BMJ Open Qual. Jul 2021;10(3)doi:10.1136/bmjoq-2020-001287
5. Riley SP, Swanson BT, Dyer E. Are movement-based classification systems more effective than therapeutic exercise or guideline based care in improving outcomes for patients with chronic low back pain? A systematic review. J Man Manip Ther. Feb 2019;27(1):5-14. doi:10.1080/10669817.2018.1532693
6. Chimenti RL, Frey-Law LA, Sluka KA. A Mechanism-Based Approach to Physical Therapist Management of Pain. Phys Ther. May 1 2018;98(5):302-314. doi:10.1093/ptj/pzy030
7. Schuttert I, Timmerman H, Petersen KK, et al. The Definition, Assessment, and Prevalence of (Human Assumed) Central Sensitisation in Patients with Chronic Low Back Pain: A Systematic Review. J Clin Med. Dec 17 2021;10(24)doi:10.3390/jcm10245931
8. Bittencourt JV, de Melo Magalhaes Amaral AC, Rodrigues PV, et al. Diagnostic accuracy of the clinical indicators to identify central sensitization pain in patients with musculoskeletal pain. Arch Physiother. Jan 11 2021;11(1):2. doi:10.1186/s40945-020-00095-7
9. Nijs J, Lahousse A, Kapreli E, et al. Nociplastic Pain Criteria or Recognition of Central Sensitization? Pain Phenotyping in the Past, Present and Future. J Clin Med. Jul 21 2021;10(15)doi:10.3390/jcm10153203
10. Fritz J. Disentangling classification systems from their individual categories and the category-specific criteria: an essential consideration to evaluate clinical utility. J Man Manip Ther. Dec 2010;18(4):205-8. doi:10.1179/106698110X12804993427162
11. Bours MJ. Bayes’ rule in diagnosis. J Clin Epidemiol. Mar 2021;131:158-160. doi:10.1016/j.jclinepi.2020.12.021
12. Riley SP, Swanson BT, Cleland JA. The why, where, and how clinical reasoning model for the evaluation and treatment of patients with low back pain. Braz J Phys Ther. Jul-Aug 2021;25(4):407-414. doi:10.1016/j.bjpt.2020.12.001