Lumbar disc degeneration more likely in overweight and obese adults

One of the largest studies to investigate lumbar spine disc degeneration found that adults who are overweight or obese were significantly more likely to have disc degeneration than those with a normal body mass index (BMI). Assessments using magnetic resonance imaging (MRI) show elevated BMI is associated with an increased number of levels of degenerated disks and greater severity of disc degeneration, including narrowing of the disc space. Details of this study now appear in Arthritis & Rheumatism, a journal published by Wiley-Blackwell on behalf of the American College of Rheumatology (ACR).

The World Health Organization (WHO) reports that obesity - one of the most preventable risk factors for a number of diseases - has more than doubled since 1980. According to WHO, in 2008 roughly 1.5 billion people aged 20 and older were overweight, with more than 200 million men and close to 300 million women considered obese. In the U.S., studies estimate one in three children is overweight or obese and excess weight could lead to more severe obesity in adulthood.

Moreover, previous research has linked higher BMI to low back pain, which is often debilitating and can limit function, impact psychological well being, diminish overall quality of life, and is associated with substantial socioeconomic and health-care costs. Experts suggest that disc degeneration is one cause of low back pain, and therefore, BMI could be involved in the development of degenerative disc disease. To expand the knowledge of this important health concern, a team of researchers led by Drs. Dino Samartzis and Kenneth M.C. Cheung at the University of Hong Kong in Hong Kong investigated the association between elevated BMI and presence, extent, and severity of lumbar spine disc degeneration on MRI in adults.

The team recruited 2,599 participants aged 21 and older from Southern China between 2001 and 2009. Participants were from diverse social and economic backgrounds and were recruited regardless of whether they had lower back pain or not. The study group included 1,040 men and 1,559 women who had a mean age of 42 years. Researchers conducted radiographic and clinical assessments, and MRIs of the lumbar spine were obtained for all subjects.

Study findings reveal that 73% of participants displayed disc degeneration, with men (76%) having a significantly higher prevalence of degeneration than women (71%). Not surprisingly, increasing age was found to increase the prevalence of disc degeneration. BMI assessments of the study group show that 7% of subjects were underweight, 48% were in the normal weight range, 36% were overweight, and 9% were obese.

Descriptions of treatment for low back pain (LBP) date to Hippocrates (460-370 BCE), who reported joint manipulation and use of traction. Onset of LBP often is associated with bipedal ambulation. Theories propose that this transformation in the mechanics of locomotion is the inciting evolutionary event that made the lumbar spine susceptible to degenerative disease. Degeneration is universal to structures that comprise the functional spinal unit, composed of 2 adjacent vertebral bodies and the intervertebral disk. The disk and 2 zygapophyseal joints at the same level function as a trijoint complex.