Towards a mechanisms-based classification of pain in musculoskeletal physiotherapy? Keith M. Smart 1 , Neil E. O’Connell 2 and Catherine Doody 3 1 Senior Physiotherapist, Physiotherapy Department, St Vincent’s University Hospital, Elm Park, Dublin 4, Ireland 2 Centre for Research in Rehabilitation, School of Health Science and Social Care, Brunel University, Uxbridge, Middlesex, UB8 3PH, UK 3 School of Physiotherapy and Performance Science, University College Dublin, Belfield, Dublin 4, Ireland The purpose of this article is to review the case for the inclusion of a mechanisms-based classification for musculoskeletal pain. In response to perceived limitations of the medical/disease model of pain and illness a mechanisms-based classification system for pain has been advocated. The classification of pain according to the underlying neurophysiological mechanisms responsible for its generation and/or maintenance may better explain the variability and complexities of clinical presentations of musculoskeletal pain and facilitate subsequent decision-making associated with the assessment, treatment and prognosis of patients with musculoskeletal disorders. However, current methods of mechanisms-based classification either lack standardised criteria or propose decision rules whose validity has yet to be substantiated empirically. While the case for a mechanisms-based classification for pain has been well made the onus rests with its advocates to (a) establish its validity for use in clinical practice in defined populations with musculoskeletal disorders, and (b) provide evidence that such a system facilitates improved clinical outcomes. Keywords: pain mechanisms, classification, musculoskeletal physiotherapy Introduction Pain, defined by the International Association for the Study of Pain (IASP) as ‘an unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage’, 1 is a complex multi-factorial phenomenon and represents the main symptom with which patients present to musculoskeletal phy- siotherapists. 2,3 Between 11 and 30% of the popula- tions of European countries have a persistent pain problem of which spinal/back pain is the most common. 4 Approximations indicate that one-fifth of patients with persistent pain problems have been diagnosed with depression as a consequence of their pain, and one-fifth have lost their job. 4,5 As such, persistent pain represents a major public health concern for which physiotherapists are frequently consulted. 4 Historically, a number of models and theories have been proposed to account for clinical presentations of pain (and associated disability), such as the 17th century Cartesian model of pain, the 19th century ‘specificity theory of pain’ 6 and the 20th century ‘central summation’, 7 ‘sensory interaction’, 8 ‘gate control’, 9 biopsychosocial, 10 mature organism model 11 and neuromatrix 12 theories. These theories show an evolution of concepts and thinking away from the simpler cause and effect approaches inherent in the Cartesian model and specificity theory, to explanations that acknowledge the neuro- biological and sociological complexities of pain and disability and its multiple determinants. ß W. S. Maney & Son Ltd 2008 DOI 10.1179/174328808X251984 Physical Therapy Reviews 2008 VOL 13 NO 1 1