The overweight and obese may be at greater risk for lumbar disc degeneration

An elevated body mass index, especially for those in the obese range, was found to increase the extent and severity of disc degeneration in a population-based study conducted in China.

Dino Samartzis, DSc, of the Department of Orthopaedics and Trauma, University of Hong Kong, presented the results of the study at the 2010 Annual Meeting of the American Academy of Orthopaedic Surgeons in New Orleans.

“Our study is the first large-scale population-based study to not only note that elevated BMI values are associated with disc degeneration, but that they may affect the extent and severity of disc degeneration of the lumbar spine,” Samartzis told Orthopedics Today. “Our study also noted a clear trend association or dose-response between increasing BMI severity and the likelihood of having disc degeneration.”

Cross-sectional analysis

Samartzis and his colleagues performed a cross-sectional analysis of 2,252 individuals of Southern Chinese origin who underwent sagittal T2-weighted MRI of the lumbar spine. The study included 906 men and 1,346 women with an average age of 41.4 years.

The investigators found disc degeneration in 1,598 individuals and noted that body mass index (BMI) was significantly higher in individuals with disc degeneration compared to those without disc degeneration. They also noted that as the BMI category severity increased, the prevalence of multilevel disc degeneration involvement increased.

“To further clarify, an individual who was overweight had an odds ratio of 3.2 or a 320% increased risk of having lumbar disc degeneration,” he said. “Likewise, someone who is obese was found to have a 530% increased risk of having disc degeneration.”

Degenerative disc disease

Samartzis also reported that an individual’s degenerative disc disease (DDD) score increases with an increase in BMI.

“We have found that as DDD score severity increases in our population, it also significantly increases the risk of having low back pain,” he said.

Although this study indicates being overweight or obese as risk factors for lumbar disc degeneration, the exact nature of the relationship is still unknown. Samartzis suggested altered biomechanics on the disc, systemic inflammatory processes, metabolism, genetics or an interaction of many factors as possible explanations.

Public health concern

“Since many novel technologies are being developed to treat disc pathology and low back pain, understanding the pathways of how being overweight or obese can affect the back may help optimize treatment modalities and outcomes,” he said. “At the most fundamental, if we understand how being overweight and obese can affect the disc, preventative strategies for disc degeneration or more severe forms of the condition can be developed.”

With regards to the public health concern raised by these findings, Samartzis said, “We should not only be cognizant that BMI is a factor associated with the development of circulatory [disease], cardiovascular disease and diabetes as well as other conditions, but also possibly with the development of disc degeneration, the severity of disc degeneration and, with that, low back pain, which in and of itself is a global burden.”

Reference:

Samartzis D, Karppinen J, Luk KDK, Cheung KMC. Body mass index and its association with disc degeneration of the lumbar spine in adults. Presented at the 2010 Annual Meeting of the American Academy of Orthopaedic Surgeons. March 9-13. New Orleans.

The study was funded by the Area of Excellence Program of Hong Kong.

Dino Samartzis can be reached at the Division of Spine Surgery, Department of Orthopaedics & Traumatology, University of Hong Kong; +852-9584-2395; e-mail: dspine@hku.hk.