Chapter 2 The problem of back pain

Just about any book or paper you read on low back pain (LBP) introduces the subject by restating the fact of the increasing ‘epidemic’ of low back pain and its enormous cost to society. We can fly man to the moon yet despite the advances of modern science the effective diagnosis and treatment of back pain remains somewhat of an elusive dilemma. Is it perhaps a case of losing sight of basic principles? To utilize Feldenkrais’¹ term, is it missing ‘the elusive obvious’?

According to Janda,² excluding insidious pathology, most musculoskeletal pain is the result of impaired function in the motor system. Pain serves an important biological function,

It might even be said that the motor system suffers from our whims and thus has no other way of protecting itself than by producing pain’.²

The Eastern medical paradigm would tend to view pain as a valuable sign signalling harmful overstress in the system. Western medicine has had a vested interest in treating pain as a disease and back pain has certainly become this.

The diagnosis dilemma

Waddell ³ says: ‘only with the introduction of western medicine does chronic back disability become common’. The approach of contemporary medicine is to search for a ‘pathological’ diagnosis, the cornerstone for instituting appropriate treatment. However, definite structural pathology is only evident in about 15% of patients with back pain.³^–⁵ The relationship between imaging and symptoms is weak.^4,⁶ There are inherent limitations to the accuracy of diagnostic tests and imaging studies have their greatest value in the exclusion of other conditions.⁷ There is often relatively weak agreement between the results of medical ‘physical examination’ and the subjective reporting of pain and disability.⁸ As Waddell³ suggests the problem of back pain exists ‘because we cannot diagnose any definite disease or offer any real cure’ – ‘if back pain becomes chronic patients soon realize that we do not know what is wrong’; and ‘so when treatment for back pain fails, the professional may look for psychological reasons or other excuses’; ‘the patient is likely to become defensive and both patient and professional may become angry and hostile’. Litigation and the potential ‘reward’ for back pain further muddy the waters. However, Hendler et al.⁹ point out that the psychiatric abnormalities that are the normal response to chronic pain coupled with litigation tend to bias many physicians resulting in less extensive evaluation. They reported finding an organic origin for the pain, which had been overlooked in 98% of their sample group, who had been variously diagnosed as ‘chronic pain’, psychogenic pain’ or lumbar strain’. No wonder the ‘biopsychosocial model’¹⁰ has evolved.

To aid diagnosis, Waddell ³ suggests a simple ‘diagnostic triage’ approach to determine management. As part of this framework, screening for ‘red flags’ indicating possible insidious pathology and ‘yellow flags’ indicating psychosocial risk factors are considered. Most patients will fall into either of three categories:

• Ordinary backache – ‘the common or garden non-specific low back pain’

• Nerve root pain

• Serious spinal pathology which accounts for less than 1% of cases.

Most back pain is ‘ordinary backache’ which is ‘nonspecific’.³ The remainder of patients have a ‘specific’ factor to account for their pain. Zusman¹¹ suggests that the term ‘non specific’ means essentially the inability of orthodox medicine to arrive at a definitive diagnosis for pain largely on the basis of structure, anatomy and biomechanics (SAB). However the patient has come to expect a SAB basis for his pain and may well prefer any reasonable diagnosis to uncertainty. The ‘disc’ provided a very handy hook on which the patient could hang his hat. Concerned people immediately ‘understood the problem’. Unfortunately, as a result of these SAB beliefs and ‘failure for various reasons, to obtain acceptable levels and/or duration of pain relief usually in association with the unproductive sequence of providers and treatments, effectively renders these patients chronic, partial or complete activity intolerant cripples’.¹¹ The patient’s belief that the pain may signify ‘serious damage’, and provoking it might cause disablement, contributes towards the fear of moving, known as ‘fear avoidance beliefs’³. The recognition of the negative impact of fear avoidance beliefs and deconditioning behavior led to the establishment of various task force groups that suggested the ‘de-medicalization’ of back pain and the avoidance of inactivity.¹² This was further reinforced by the Paris Task Force on Back Pain¹³ which recommended the early resumption of ‘activity of any form – rather than any specific activity’. Whilst these recommendations are understandable in helping to stem secondary factors contributing to the magnitude of the problem it is not a specific therapeutic solution to the underlying problem. In fact for many, the ‘keep them moving’ advice has contributed to the further entrenchment of already dysfunctional movement patterns, serving to perpetuate their ‘non specific chronic pain’ problem. If ‘activity’ and therapeutic exercise are to be effective they must specifically redress the actual impairments.

Classification systems for chronic low back pain

Chronic non specific low back pain (CNLBP) or ‘ordinary’ backache accounts for approximately 85% of back pain. The lack of a specific diagnosis has resulted in the lack of specific treatment interventions and poor outcomes. Various clinical classification systems have been proposed in attempt to improve intervention outcomes, some with dubious veracity.¹⁴ In a review of the literature, Riddle¹⁵ notes some classification systems are designed to determine the most appropriate treatment, some to aid in prognosis, and others to identify pathology. Still others place patients into homogenous groups based upon selected variables. Examining these is inclined to give one a headache, so laborious can they be. Riddle highlighted the limitations of the four most commonly cited systems, found those in current use did not meet many of the measurement standards and clinical utility was unclear.

The biopsychosocial paradigm acknowledges that CNLBP is a multifactorial problem.³ Treatment interventions will only show positive outcomes when they appropriately address the patient’s actual prime impairments. O’Sullivan¹⁶ stringently argues for a classification system based upon the specific mechanism underlying and driving the pain disorder. He provides an excellent overview of the current operant classification/ diagnosis models which are summarized below.

• Patho-anatomical model. The traditional medical approach where abnormal structural findings such as ‘disc prolapse’ are assumed to be the cause of pain and treatment interventions provided on the basis of this assumption. (Extraordinarily, it appears that ‘function affects structure’ is rarely considered.)

• Peripheral pain generator model. Identification of the painful structure based upon history, clinical examination and diagnostic blocks. Treatment such as blocks and denervation procedures address the pain symptom without consideration for the underlying mechanism.

• Neurophysiological model. Central sensitization of pain secondary to sustained peripheral nociceptive input and changes in cortical mapping. Medical interventions inhibit both central and peripheral processing of pain.

• Psychosocial model. The impact of psychological and social factors upon the modulation of pain and in particular their capacity to increase the CNS mediated drive of pain. Poor coping strategies, anxiety, catastrophizing, hyper-vigilance tend to increase pain levels, disability and muscle guarding. Cognitive behavioral interventions can be effective. There is only a small subgroup where these factors are primary. The danger, however, is that due to lack of an alternate diagnosis, physiotherapists are tending to classify most patients with CNLBP as primarily psychosocial driven. This is significant!

• Mechanical loading model. Both high and low levels of physical activity are reported risk factors for LBP; sustained end range loading; sudden and repeated loading, and related mechanical exposures are also influenced by ergonomic and environmental factors and have the potential for ongoing peripheral nociception and need to be addressed as part of management.

• Signs and symptoms model. Impairments in spinal movements and function, changes in segmental mobility, pain provocation tests; the effect of repeated movement on pain. The approaches of Maitland ¹⁷ and McKenzie¹⁸^–²¹ fall into this model which is based upon biomechanical and patho-anatomical models and have led to the treatment of signs and symptoms associated with CNLBP. Limited evidence of efficacy may reflect research designs and neglecting the biopsychosocial dimensions.

• Motor control model. This model includes the approaches of Richardson and Jull ²², Sahrmann²³ and O’Sullivan.^24,²⁵ Movement and control impairments are highly variable and their presence does not establish cause and effect. Altered motor behavior is either protective or maladaptive which results in ongoing abnormal tissue loading and mechanically provoked pain. This group are amenable to tailored physiotherapy interventions directed at their specific physical and cognitive impairments with demonstrated positive outcomes.

• Biopsychosocial model – the multidimensional approach to dealing with CNLBP. The relative contributions of the different dimensions and their dominance will differ for each patient. Clinical reasoning allows determination as to which factors are dominant. Consideration of all factors allows for a diagnosis and mechanism based classification guiding management.

The subject of this book makes the case for adding another category to those summarized by O’Sullivan.

• Functional movement model. This encompasses the biopsychosocial paradigm with the major focus upon improving the understanding and skill of the physical therapist in better dealing with the problem of movement dysfunction in spinal pain disorders. It sees that altered function in the posturomovement system is the primary problem largely responsible for the development and perpetuation of most pain syndromes. A simple clinical classification system based upon altered posturomovement function guides assessment functional diagnosis and management. Specific, appropriate treatment interventions directed to both the ‘peripheral pain generator’ and the altered posturomovement function improves pain and ability and helps counter the development of secondary psychosocial problems. Restoring neurmyoarticular function helps restore the person.

The model is cognisant of all the above models but mainly rests within models 5–8 described above.