Just published in Physical Therapy in November 2022 is a proposed new model for addressing the problem of chronic low back pain (CLBP) in physiotherapy: The Fit-for-Purpose model (Wand et al., 2022). The Fit-for-Purpose model is based on the view that people with CLBP hold strong beliefs that their back is fragile, damaged, unhealthy and unchangeable. Because these beliefs are widely held in society, information that counters those beliefs are often disregarded. Wand and colleagues propose a model that aims to shift those beliefs towards an understanding and experience of a healthy, adaptable and strong back that is indeed fit for purpose.
In my view, the Fit-for-Purpose model compared with other current treatment models for CLBP goes further than Pain Neuroscience Education (PNE) and graded exercise in incorporating an understanding of the impact of pain and threat perception on the person’s ability to process sensory information. The Fit-for-Purpose model incorporates a stage for retraining precise sensory and motor function to enable the person to feel safe again in their body.
Safety in the body depends on the individual’s conscious and unconscious interpretation of multiple sensory sources from current and previously learned information. Wand and colleagues suggest that pain is an actively constructed experience based on the perception that the body is under threat and in need of protection, and this is influenced by psychological and social factors. These factors are intertwined with the foundational neurobiological processes that emerge as a conscious experience recognised as pain.
What factors underpin the Fit-for-Purpose model?
Factors that lead to CLBP are: (1) changes in musculoskeletal health reducing back fitness and load tolerance; (2) sensitisation towards noxious information from the back; (3) decreased proprioceptive and tactile sensory information resulting in reduced input of non-noxious somatosensory information; (4) disrupted sensory and motor neural representations of the back in the sensory and motor cortices of the brain.
Wand and colleagues propose that these factors lead to degraded motor control of the back and alterations in self-perception of the back such that it starts to feel foreign, disconnected, unfit and somewhat peculiar. There is a growing body of evidence that persistent pain is associated with progressive disruptions in sensory and motor awareness and processing of bodily feedback. Such disruptions can be distressing and reinforce the individual’s beliefs that the body is not fit-for-purpose.
Central to the Fit –for-Purpose model is the potential for self-sustaining interactions between perceptual and cognitive models, i.e. how the body in pain feels and how the individual thinks about the body in pain, respectively. A body that was initially conceptualised as damaged, fragile and unhealthy, increasingly feels as such. The view that the back is not fit-for-purpose and in need of protection is thus reinforced, which may become self-sustaining.
How are the factors addressed through the Fit-for-Purpose model?
The Fit-for-Purpose model proposes four stages in the restoration of beliefs, sensorimotor function and fitness for goal-derived functional purposes. These are outlined as follows:
1. Understand that it is safe and helpful to move
This PNE stage aims to improve an individual’s understanding of how pain happens, including: (1) the distinction between nociception and pain; (2) the clinical understanding that the extent of pain does not represent the extent of tissue damage; (3) the changeable sensitivity of nociceptors and factors that increase and decrease sensitisation; (4) the multifactorial processes that contribute to the experience and persistence of pain; and (5) the encouragement that biological systems tend to adapt to the demands placed upon them which can be used to the individual’s advantage for recovery. (Image 1 text wrapped here)
2. Refine neural representations of the body so the back feels safe to move
Normalising the disrupted sensory and motor processing through neural representation training may help the individual feel safer to move, and in turn reinforces the central educational message that the back is safe to move. Over the years, studies have shown that tactile acuity, sensory and motor perceptions, altered motor imagery performance and altered motor control are features of CLBP. Wand and colleagues suggest strategies for graded retraining of sensory precision, motor imagery and motor control, as outlined in Table 1.
Table 1: Strategies suggested by Wand and colleagues for the Refine stage of the Fit-for-Purpose model, to retrain sensory precision, motor imagery, motor control and precision.
Motor Imagery (GMI)
Motor Control / motor precision
Low load precision-focused and feedback-enriched:
- independent spinal movements
3. Load the back to promote positive tissue adaptation and experience safety with movement
Using the principle that the bioplasticity of the body means that the back will adapt to its demands in a healthy way to increase its fitness for purpose, the following strategies are suggested for this stage of the rehabilitation:
a. Precision-focused and feedback-enriched graded exercises with graded increases in loading. This might also include contextual and cognitive loading.
b. Partial- then whole-practice of functional tasks relevant to the individual’s goals.
4. Consolidate safety under load
Ongoing general exercise prescription of increasing intensity that integrates skills learned above and is orientated towards patient-derived goals.
I like the Fit –for-Purpose model because it incorporates so many physiotherapy rehabilitation elements (e.g. cognitions, perceptions, movement function and tissue tolerance to load) which, when addressed in isolation, have not always been shown to be effective for individuals with CLBP. People with CLBP are individuals with different stories and influences on their threat perceptions and responses. However, there are common inter-individual elements which the Fit-for-Purpose model addresses - a lack of understanding that the back is fit for purpose, loss of refinement of sensorimotor function and loss of load tolerance.
The Fit –for-Purpose model does not take into account different coping styles which may require individual tailoring of rehabilitation. For example, individuals with CLBP and a Defensive High Anxious* coping style may tend to pay attention to multiple sensations from the body and interpret them for threat (Clark, Nijs, Yeowell, Holmes, & Goodwin, 2019; Franklin, Holmes, Smith, & Fowler, 2016), whereas the Repressor* coping style may tend to pay minimal attention to body feedback, and may therefore receive inadequate normal sensory cues (Eysenck, 1997). Inadequate processing of sensory cues may reinforce evidence from the back that it is not fit for purpose because of the altered sensory processing. These two coping styles may present differently and require a different level of emphasis at each of the four stages of the Fit-for-Purpose model rehabilitation.
The concept of the Fit-for-Purpose model by Wand and colleagues proposes four rehabilitation stages for individuals with CLBP and can be summarised as: 1) Understand, 2) Refine, 3) Load and 4) Consolidate. Based on my own clinical experience, this seems to be an exciting new model and I look forward to seeing results of the testing to show effectiveness on outcomes in CLBP.
*Defensive High Anxious coping styles are high in trait anxiety and high in defensiveness, as measured by the State-Trait Anxiety Inventory and the Marlowe Crowne Social Desirability Scale respectively. Repressor coping style is low in self-report trait anxiety and high in defensiveness.
Dr Jacqui R Clark PhD
Registered Specialist Pain Physiotherapist, New Zealand, working clinically at Pains and Brains www.painsandbrains.com
References and further reading: http://www.sciencedirect.com/science/article/pii/S...
Clark, J. R., Nijs, J., Yeowell, G., Holmes, P., & Goodwin, P. C. (2019). Trait Sensitivity, Anxiety and Personality are predictive of Central Sensitisation Symptoms in Patients with Chronic Low Back Pain. Pain Practice.
Eysenck. (1997). Anxiety and Cognition. A Unified Theory. HoveUK: Psychology Press.
Franklin, Z., Holmes, P., Smith, N., & Fowler, N. (2016). Personality Type Influences Attentional Bias in Individuals with Chronic Back Pain. PloS One, 11(1), e0147035.
Wand, B. M., Cashin, A. G., McAuley, J. H., Bagg, M. K., Orange, G. M., & Moseley, G. L. (2022). The Fit-for-Purpose Model: Conceptualizing and Managing Chronic Nonspecific Low Back Pain as an Information Problem. Physical Therapy.