Characterisation of optimal lumbar spinal posture: relationship to joint degeneration and relevance to treatment of low back pain

Osteoarthritis (OA), [radiologically also called degenerative joint disease (DJD)], is the most common form of arthritis and is the cause of substantial morbidity. It is widely believed based on a solid body of evidence that excessive joint loading leads to knee or hip degeneration. Chiropractors and physical therapists have implied from this body of research that the same applies to the spine. Hence, they routinely assess patients for postural abnormalities as part of their new patient workup and as an outcome measure after treatment. Posture is considered an important aspect of assessment due to a possibility of postural asymmetry being implicated in altered biomechanics of weight bearing joints, concomitant muscle imbalances and spinal joint fixations, which may lead or contribute to spinal pain and disability. In these professions, elaborate assessment and therapeutic systems have developed such as 'chiropractic biophysics' in which restoration of what is considered 'normal posture' is the desired clinical outcome in treating spinal pain, particularly chronic low back pain. In addition, older patients with osteoarthritic pain and disability also constitute a large proportion of the physical or manipulative therapist's patient base. Often, these patients display moderate to severe postural abnormalities. This is generally considered to be as a result of joint degeneration and is thought to also contribute to further joint degeneration thereby setting up a vicious circle. The assumption that is commonly made in physical therapy practice in general is that mild postural distortion is associated with pain and may cause OA in the future. However, this assumption is largely based on studies that have demonstrated the link with severe postural distortion. There is indeed very little in the current literature documenting the link between mild postural distortion of the lumbar spine and OA. These correlations need further study in order to validate what is being routinely performed in private practice based on assumption. This thesis, therefore, sought to examine the possible link between excessive/abnormal joint loading as a result of mild postural distortion of the lumbar spine and the presence and severity of degenerative changes in lumbar motion segments in adults. This link was examined from epidemiological, biomechanical, pathophysiological and clinical perspectives. An interesting case of drastically abnormal biomechanics was presented in chapter 4 that exhibited a significantly different pattern of spinal OA from that commonly seen in the general population. This may indicate a significant link between biomechanical factors and the site, pattern and severity of spinal degeneration. Of course, a case-study can only indicate such a link rather than illustrate or prove it. It is important to note that the results of the lordosis and leg length discrepancy chapters of this thesis demonstrate that a positive correlation does exist between mild postural abnormalities in the sagittal and coronal planes respectively and the presence of degenerative changes in the lumbar spine. This is particularly the case in the lower lumbar spine which is the site most affected by OA. The thesis further aimed to define the optimal sagittal and coronal postures of the lumbar spine that were associated with minimal degenerative change. Consequently, studies of lumbar lordosis and leg length discrepancy were the primary focus of this thesis. Lumbar scoliosis is linked to abnormal loading of the lumbar spine, however, it was considered to be beyond the scope of this thesis. This thesis generated a host of novel findings in terms of optimal angles of lordosis with respect to age and sex in adults. It also defined the threshold of clinical significance of leg length discrepancy as detected on standard radiographic examination using novel methods to ensure validity of the quantification protocol. There is sufficient evidence in the literature, as well as common anecdotal observations from chiropractic practice, to suggest that LLD is also relevant to low back pain, particularly the chronic type. It would follow then that multimodal treatment of these patients may hold promise of greater effectiveness. Therefore, the purview of this thesis was extended to multidisciplinary treatment of LLD as a result of unilateral foot pronation, a form of functional LLD in those who suffered from CLBP. Here, a protocol for a pilot/feasibility randomised controlled trial was formulated to answer preliminary questions about a combined chiropractic and podiatric treatment approach. The purpose of this was to facilitate the possible translation of the findings of this thesis to the design of larger statistically-powered RCTs that may then lead to refinement of clinical practice to reduce CLBPs substantial burden of disease.