Is There an Association of Kyphosis and Diffuse Idiopathic Skeletal Hyperstosis in the Aging Population?

Skeletal changes are common in the aging population. Two of these changes that or prevalent among this population are kyphosis and DISH (diffuse idopathic skeletal hyperstosis) and are found through radiolographical findings. Kyphosis is an increased spinal curvature and the increase prevalence in the aging population can be associated with a decrease in bone density and decrease in back muscle density. Typically kyphosis is measured with a lateral radiograph where spine curvature can be measured using a method known as the Cobb angle measurement. DISH is diagnosed by the presence of ossification in the soft tissue in four continuous segments around the front and side of the thorocolumbar spine with the absence of degenerative disc changes. The cause of DISH is relatively unclear at this time, however, research points out there may be a genetic association hormonal, mechanical, and medication influences on its presence as well as a possible association with diabetes mellitus type 2, obesity, hyperuricemia, and male sex. While it is known that these both are prevalent in the aging population a recent study wanted to examine if there was a possible association between DISH and kyphosis.

The cross-sectional study utilized data for the Health Aging and Body Composition Study (Health ABC) which is an ongoing cohort of participants aged 70-79 years old. They recruited a random sample of age appropriate medicare-eligible Caucasian and African American subjects from the Pittsburgh, PA region. All participants were independent with activities of daily living, could walk one-fourth of a mile and up to 10 steps without rest breaks required. Radiologic assessment with the use of CT scan were utilized to examine for the presence of kyphosis and DISH. They used data from 1172 subject participants. CT scans were studied by two different musculoskeletal radiologists in assessment of DISH for reliable findings. Among participants 152 subjects were diagnosed with DISH, 101 of the cases were located in the thoracic spine and 51 cases were located in both the thoracic and lumbar regions. Overall findings showed a significant interaction of race and DISH with Cobb angle. The presence of DISH among African Americans was associated with an increase in Cobb angle of 8.9 degrees with 95 per cent confidence interval as compared to those without DISH. Among Caucasians, DISH was not significantly associated with Cobb angle. When the location of DISH was further analyzed it was found that when located in the thoracic spine alone there was a significantly associated increase in Cobb angle in both races. However, when DISH was present in both the thoracic and lumbar spine there was not an associated increase in Cobb angle in either races. Overall, these findings indicate the presence of ossification among the anterior longitudinal ligament may change the structure of the spine and affect spinal curvatures. It was found that further research would be warranted to learn whether the presence of DISH is a predictor of worsening kyphosis over time.