When it comes to lumbar degenerative disc diseases and spondylosis, a longitudinal study [1. Risk factors for lumbar intervertebral disc height narrowing: a populations-based longitudinal study in the elderly] of 197 members of the elderly population of a village in Japan suggests that females—particularly those with a history of knee and back pain—have a significantly higher chance of developing the narrowing in disc height associated with aging.
The findings of this first long-term, population-based radiographic cohort study indicate the need for further research into the pathologies involved in the mechanisms of progressive disc degeneration—specifically in the post-menopausal female population, where a reduction of the estrogen hormone—along with the gradual degradation IVD tissues and drying or malnutrition of the disc materials — may, along with a hereditary propensity, contribute to lumbar disc height narrowing.
Long-term data from a study of osteoporosis and knee osteoporosis in elderly (age 65 and above) inhabitants of a village in Japan was analyzed every other year between 1997 and 2007. The subjects were interviewed about their medical history, smoking habits, age, sex, work history, and the presence of lower back or knee pain, and their histories and responses were recorded. Researchers noted each subject’s body height and weight, body mass index (BMI), and bone density (BMD). Radiographs of each knee were recorded and graded, as well as any vertebral compression fractures or calcification of the subject’s abdominal aorta. Three certified orthopedic surgeons not privy to prior classifications independently evaluated each of the radiographs and recorded their observations.
Over the course of the 10-year study, biannual radiographs of the lateral lumbar spine area were taken of the subjects and scanned into digital medium. The scans were subsequently analyzed and measured for anterior disc height, posterior disc height, superior disc depth, and inferior disc depth. After the final examination, the subjects were divided into two groups: those whose disc heights had mildly decreased, and those whose disc heights had significantly decreased. The subjects with significant decrease in disc heights were then further divided per the location of the most affected lumbar disc relative to discs with little height decrease.
The subjects in the study showed an overall 5.8 percent decrease in disc height over the study period, uniformly manifested among disc levels. Approximately 45 percent of the subjects developed multilevel, severe degeneration of disc height. There appeared to be a notable link between reported back pain at the baseline interview and future development of significant disc height narrowing, indicating that there may be a connection between mid-life back pain and later spinal spondylosis.
There was a dramatic increase in disc height narrowing in the female subjects, compared to male subjects. Risk factors including BMI, height, weight, smoking habits, osteoporosis, knee pain, work history, diabetes treatment, radiographic calcification of abdominal aorta, hypertension, work history, kidney, liver, or thyroid disorder, tuberculosis, and gout appeared to have little association with the manifestation of disc height narrowing in this study, though prior studies have indicated a link between being overweight and lumbar disc degeneration in middle-aged men, adolescents, and juveniles.