CAN BIOMECHANICS RESEARCH LEAD TO MORE EFFECTIVE TREATMENT OF LOW BACK PAIN? A POINT-COUNTERPOINT DEBATE

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Review written by Robin Kerr

BACKGROUND & OBJECTIVE

The growing interest in the Bio-Psycho-Social (BPS) paradigm in medicine, particularly in the physical therapies, is promoting a move away from the classic biomechanical view of the “body as a machine” in the management of persistent/recurrent low back pain (LBP). Despite this shift, many still practice heavily from a biomechanical perspective(1).

This paper compiled the research supported views of eight highly respected researchers/therapists (Cholewicki, Breen, Popovich, Reeves, Sahrmann, van Dillen, Vleeming & Hodges), in a debate as to whether biomechanics ALONE can provide the basis for intervention in low back pain. A point – counterpoint format was taken to present both sides of the argument.

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VIEWPOINT 1: Consideration of biomechanics alone is unlikely to lead to more effective treatment strategies for low back pain

The panel highlighted that elegant biomechanical studies had been performed in the past from which various treatment strategies were designed to address the proposed mechanisms. The initial example was of deficits in TrA recruitment from which motor control rehabilitation and trunk stabilisation exercises arose (Hodges). Further examples were the Movement System Impairment (van Dillen & Sahrmann) and directional preference work of the McKenzie Method. The panel agreed that these models held internal validity being based on sound anatomical, biological and mechanical principles. The relationship between pain and the biomechanical measures of these models was supported by differences seen in the research between low back pain and healthy controls.

The question raised however was whether these biomechanical representations of low back pain resulted in effective interventions. Analysis of SR & RCTs revealed that biomechanical models alone were not superior to other forms of exercise or treatment when applied to chronic non-specific LBP. This raised the subject of patient subgrouping, (i.e. specific patient subgroups responding best to specific interventions), the conclusion being that sub-grouping methods remain elusive (2). The panel suggested that low back pain is a multifactorial problem, in which any individual factor or mechanism only plays a small role. Treatment strategies that treat one dominant factor will be less effective than treating multiple arbitrary factors in such complex multifactorial presentations (3).

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Compounding difficulty in evaluating the RCT and SR research on biomechanical interventions are the non-specific effects associated with various therapeutic modalities (e.g. placebo, therapeutic alliance effects), and the ability to design a double-blind sham treatment not being possible.

2. COUNTERPOINT: Biomechanics research can lead to more effective treatment strategies for low back pain

A) Biomechanical Model 1 (Breen): Intervertebral Mechanical Dysfunction in Non-Specific LBP Breen agreed that mechanical dysfunction cannot be a single explanatory variable for low back pain, however argued that most low-back pain presentations are affected by movement or position, indicating

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