A Biometrical investigation into the relationship between vertebral joint osteophytosis and body proportion biomechanics.

Abstract

Occupational loading is a significant risk factor for back pain and vertebral joint disease. Although biomechanical principles predict that spinal loading is affected by body proportion, particularly with differences in upper to lower body measurements, these differences have not previously been investigated in anthropometrical studies. This research is innovative as it aims to provide a functional explanation for vertebral pathology through the use of biomechanical models and the study of biometric data from documented skeletal samples. Particular emphasis is placed on occupation and occupational health in the 18th and 19th Century silk weaving community. Appendicular and axial measurements were recorded along with the presence and severity of vertebral osteophytes. Ratio variables were created in order to investigate the biomechanical models. The frequency of vertebral osteophytosis was determined in relation to sex and age-at-death. Statistical analyses were performed with regards to age-at-death and both vertebral osteophytosis and the metric measurements, as well as between sex and the metric variables. The association between vertebral osteophytes and the metric variables was also analysed. A significant interaction was observed between age-at-death and both vertebral osteophytes and the metric measurements, which was subsequently controlled for in the statistical analyses. In males, vertebral osteophytes in the lower thoracic and lumbar spine were associated with greater skeletal measurements, while those in the cervical and mid thoracic region were related to smaller dimensions. In females, osteophytes were for the most part associated with larger measurements. The analyses of the ratio variables showed that vertebral osteophytes were significantly associated with larger upper to lower body dimensions in males. The skeletal measurement results suggest that there was either an ergonomic constraint in the working environment, possibly as a result of equipment size and/or operation, or a propensity towards specific occupations being linked to body size, which is supported by contemporary accounts. The ratio variable results substantiate the predictions of the biomechanical models that a greater upper to lower body size ratio is associated with increased spinal loading.