The effect of anterior osteophytes and flexural position on thoracic trabecular strain

Study Design. Compressive and shear trabecular strains were evaluated using six cadaveric thoracic spines that included anterior osteophytes. The trea tments were divided into three groups: 1) osteophytes intact and the specim en in the neutral position, 2) osteophytes removed and the specimen in the neutral position, and 3) osteophytes removed and the specimen with 5 degree s of additional flexion. Objectives. To investigate the influence of osteophytes and flexural positi on on vertebral trabecular strain during axial compression. Summary of Background Data. In the thoracic spine, the incidence of anterio r wedge fractures increases with the severity of kyphosis. It is unclear wh ether the role of anterior osteophytes in the thoracic spine is to restrict progressive kyphosis, conduct axial load anteriorly, or both. Methods. Thoracic motion segments, T10-T12, were axially loaded in compress ion, and the minimum principal and maximum shear strains were measured usin g texture correlation. Results. No dramatic changes were found in the spatial distribution of the strains following removal of the anterior osteophytes, Conversely, after re moval of the osteophytes and orienting the specimen in 5 degrees of additio nal flexion, the strain distribution shifted anteriorly and the magnitude i ncreased. Conclusions. This study demonstrated that osteophytes seem to restrict prog ressive kyphosis rather than conduct axial load anteriorly.