Read Time: 10-12 min
Believe whatever you believe by day, but at night, argue against the propositions you hold most dear”
– How not to be Wrong: The Power of Mathematical Thinking by Jordan Ellenberg
Last week we covered the four primary models of treatment for motor control impairments: Movement System Impairments (MSI), Mechanical Diagnosis and Therapy (MDT), Motor Control Training (MTC), and Integrated Systems Model (ISM). Like any ‘school of thought’ or treatment model, there are both positives and negatives. The primary positive is that treatments matched to a subgroup typically provide superior outcomes compared to a generalized approach. Phil Hodges sumamrizes why is his paper Hybrid approach to tailoring treatment for low back pain: a proposed model of care:
“Low back pain is a complex and heterogeneous condition that has considerable variation in its presentation and the underlying mechanisms of symptom development and progression.
He goes on to describe how low back pain presentations differ within biological, psychological, and social constructs. Basically, all low back pain is not created equal and therefore all low back pain should not be treated the same (assuming you are one of those therapists who likes getting ideal outcomes). However, despite a more narrowed focus, most treatments methods fall short of consideration of the multidimensional nature of low back pain, often failing to consider psychosocial issues. Remember, pain is wildly complex and consists of many contributing factors, most of which are not assessed within the subgroups, and thus may be ignored in the treatment interventions chosen. Even an appropriate subgrouping fails to consider many patient variables (e.g. diet and sleep) that can directly impact variables of the interventions chosen (such as intensity and recovery time).
So, what does this all mean for you? We are still waiting on the magical protocol that will cure all low back pain. In the meantime, we can add another piece to the puzzle. Instead of treating the specific approaches as the premier and exclusive options, why not develop a hybrid and personalized approach. This is what Phil Hodges is advocating for in his paper (and I quite agree). But before I share this thorough model, we have a couple more layers to add.
The goal of the hybrid model is a melding of two separate approaches. 1
- Care based on prognosis (identify prognostic variables)
- Care based on subgroups expected to respond to specific treatments (identify treatment moderators).”
For the prognosis piece, there are a couple roads we can take but any route will have its limitations. This too is a beast of a topic (the whole predicting the future thing can be tricky) and we won’t dive too deep into it. What Phil Hodges advocates for is a commonly used tool in the field of PT. The STarT Back screening tool establishes whether a patient with low back pain has a low-risk, medium-risk, or high-risk for a poor prognosis. Those in the low-risk category are recommended to receive minimal care. Instead, provide reassurance of a good prognosis and advice to remain active. Those in the high-risk category receive intensive psychologically informed treatment (a biopsychosocial approach). Those in the medium-risk category are recommended multimodal physical therapy that is applied according to Clinic Practice Guidelines (which is another issue, given the low back pain CPG is 8 years old)2. Unfortunately, there is limited clear guidance regarding decision making and details of interventions. That is where the second piece of the proposed hybrid model comes into play.
As we have established, many considerations come into play when determining what treatment methods to utilize. The recommendations for the “low-risk” group remain relatively the same. The duration and intensity of care is likely less. The important treatments are providing advice and education to reassure patients of their positive prognosis, comfort any worries about being “broken” or “damaged,” and educate that low back pain is common. Additionally, a primary goal is to encourage resumption of normal activity and provide education on a healthy lifestyle (sleep, diet, physical activity, stress management). However, there is a caveat to all of this.
Atrophy of the multifidus muscle occurs during an episode of acute low back pain, typically on the painful side.3 Additionally, muscle activation alters during acute pain, although whether it increase or decreases differs (i.e. loose vs tight control) indicating the nervous system is likely attempting to “protect” the spine. The rapid atrophy (occurs in about 3 days from onset of pain) is a result of the immediate reduction in excitability of spinal neural pathways (reflex inhibition). Interestingly, low intensity exercises with precise activation of the multifidus are enough to restore multifidus size. It is important to note that this type of exercise would lack sufficient stimulus to induce muscle hypertrophy (note underlining of restore), indicating early muscle atrophy is likely not related to loss of muscle fiber mass. Simply activating the multifidus is sufficient to overcome inhibition and subsequently restore muscle health. Again, note the emphasis on multifidus specific exercises. General exercise or simple extension of the spine is unlikely to suffice, as spinal extension can be achieved in many ways without the use of the multifidus (particularly the deep multifidus).
These findings support the argument that patients would benefit from specific exercises prescribed by a therapist during acute low back pain. That is not to say the duration and intensity of treatment will equal that of patients in the subacute or chronic stage, but general exercise recommendation may be insufficient and increase the risk for future pain, dysfunction, and functional limitation. With that said, therapists need to be careful to avoid creating a nocebo effect when recommending specific exercises. Still convey the primary message of a positive prognosis rather than instilling a belief the patient is “at risk” and creating catastrophizing attitudes and actions.
What about the subacute and chronic stages? Studies have shown differences in total (muscle and fat), lean muscle, and fat cross-sectional areas of the multifidus, erector spinae, and psoas muscles when compared to control (greater for chronic than subacute).4,5 More specifically, the differences were in fat infiltration in lean muscle tissue. The muscle-fat index was also higher for patients in LBP remission for all previously listed muscles compared to controls. Differences were found on both sides (not just the painful side) and were correlated with the frequency of LBP episodes. This provides further evidence to avoid treating all acute or subacute patients the same. We will see differences if a patient is experiencing their first episode of acute low back pain compared to someone experiencing recurrent low back pain, regardless of the stage of symptoms for this specific episode. Keep in mind, we also have studies demonstrating differences in the cortex depending on the frequency of LBP. Additionally, we need to consider how past experiences of LBP can affect patient expectations, fear-avoidant behavior, catastrophizing, pain behavior. See the issues with treating patients with LBP as a homogenous group? The chronicity of symptoms is an important consideration when developing a plan of care, but the history of potential previous episodes needs to be considered as well.
Now that we covered the prognostic variables, on to the treatment moderator variables. For this category, we need to investigate the drivers of the patient’s symptoms, specifically their pain.
Research has largely grouped pain into three general categories. These categories – nociceptive pain, neuropathic pain, and central pain (central sensitization) – impact which interventions clinicians choose. Identifying the likely driver of pain will lead to biases of treatments, for example, nociceptive pain would lead to a larger emphasis on physical features during the assessment and treatment while central pain would lead to more emphasis on the psychosocial domain. Keep in mind, this is not cut and dry. Patient can experience a blending of these pain mechanisms and thus require a mixed treatment approach. Once again, this highlights the difficulty with creating a “structured” treatment approach that can be applied to a multitude of patients. However, assessing for the primary drivers can help guide a more appropriate treatment approach.
If someone’s pain is primarily maintained by central sensitization, they will likely have far more success receiving a plan of care focused on psychologically informed treatment. While exercise is an important intervention for this population, the goals of the exercise may slightly differ. Rather than considering and emphasizing strength, power, endurance, or hypertrophy when choosing exercise rep schemes and intensities, using movement as a behavior intervention, such as graded activity, can influence behavior and cognitions about pain. The intent is to foster a healthy movement experience, reduce apprehension with activity, and facilitate return to function. In addition, treatment should emphasize a healthy lifestyle (one could argue this should be the case for all patients, but it will likely be even more impactful in this population) through education on sleep hygiene, diet, and stress management.
If a patient is placed in the nociceptive group, then we consider many of the topics from the previous two posts (part1, part 2). Here we would identify suboptimal tissue loading strategies and gear our interventions more towards motor control, strength, power, hypertrophy, and endurance. For the most part, all the motor control approaches presented previously operate under the assumption that pain is maintained by persistent nociceptive input from tissue loading. Therefore, utilizing an appropriate approach to address motor control impairments and resulting adaptations (atrophy, weakness, strength and power deficits), is the primary focus of exercise interventions. Bear in mind, many patients don’t neatly fall into a specific scheme. Additionally, it is important to remember that nociceptive input and pain perception is not a one-to-one relationship and our education and exercise interventions should not represent that. Furthermore, pain does not equate tissue damage. Education and a biopsychosocial approach will still be needed despite nociception being the primary driver of pain.
For individuals with neuropathic pain, treatment is multifactorial and consists of a blend of physical and psychological approaches. While all pain drivers require a mixed approach, loosely you can think of nociceptive pain treated primarily with physical approaches, central with psychosocial, and neuropathic somewhere in-between. Nerve loading is often a concern in this population; therefore, interventions would need to focus on posture, movement, and muscle activation. Neurodynamic assessments may be used to highlight specific patient needs and provide further refinement of treatment interventions. Below is the full hybrid model.
So, what am I left with? A more comprehensive approach to LBP. Is it perfect? Absolutely not. Is it a step in the right direction? Based on the evidence we have now, yes. Keep in mind, 10 years from now, we could look back on this “masterpiece” of a blog series and laugh at my ignorance. That is the incredibly cool and often frustrating thing about Living Clinically. To stay up to date with the evidence means you have to be willing to admit you were wrong and change your clinical practice, even if it was “right” previously (hello theory-induced blindness) and regardless of the time and effort invested (good seeing you again sunk cost fallacy). We don’t want to get board after all.
ABOUT THE AUTHOR
Zach has numerous research publications in peer-reviewed rehabilitation and medical journals. He has developed and taught weekend continuing education courses in the areas of plan of care development, exercise prescription, pain science, and nutrition. He has presented full education sessions at APTA NEXT conference and ACRM, PTAG, and FOTO annual conferences multiple platforms sessions and posters at CSM.
Zach is an active member of the Orthopedic and Research sections of the American Physical Therapy Association and the Physical Therapy Association of Georgia. He currently served on the APTA Science and Practice Affairs Committee and the PTAG Barney Poole Leadership Academy.