Swedish researchers looked at the impact of degenerative changes in the lumbar spine using measurements obtained from dual-energy x-ray absorptiometry (DXA) over time. They also examined the implications for diagnosing patients with osteoporosis.
Their paper, “Degenerative changes at the lumbar spine - implications for bone mineral density measurement in elderly women,” was presented at the 2011 Annual Meeting of the American Society of Bone and Mineral Research.
The study included 1,044 Swedish women from the population-based Osteoporosis Prospective Risk Assessment study (OPRA).
At the start of the study, participants were 75 years old. The researchers followed up after 5 years (n=698) and then again at 10 years (n=380).
Lunar DPX-L DXA was used to determine the study participants’ BMD levels.
The following degenerative changes were evaluated visually on the DXA for each vertebra from L1-L4 (the intra-observer precision kappa values were 0.66-0.7):
For the purposes of this study, evaluation of spinal x-rays was also made for comparison.
Researchers noted that at baseline, degenerative changes were more frequently observed in the distal part of the lumbar spine (L1: 5%; L2: 15%; L3: 26%; L4: 36%), and these changes increased over time.
At the 10-year follow-up, incidence manifested as a significant increase in overall BMD levels (L1: 20%; L2: 39%; L3: 59%; L4: 72%).
Re-analysis following exclusion of all patients who had degenerative changes in the lumbar spine resulted in BMD remaining stable between 75 to 85 years old rather than bone loss, which researchers anticipated.
At baseline, using these criteria (BMD for L2-L4; standard deviation: <2.5), the research team found that 33% of the study participants had osteoporosis. When researchers excluded participants who had degenerative changes, the percentage of people with osteoporosis increased to 42%.
Using L1-L2—vertebrae that are less prone to degenerative changes—as the diagnostic site, 46% of the study participants were classified as having osteoporosis.
Bisphosphonates, calcium, hormone replacement therapy, and vitamin D did not significantly alter the results.
These findings confirm that degenerative changes:
In addition to these findings, researchers noted that even in the absence of degenerative changes in elderly women, BMD is maintained—not lost—over time. DXA is an accurate way to identify degenerative changes and when it’s used with BMD measurements, it improves interpretation of a patient’s osteoporosis status. The researchers recommend that routinely assessing L1-L2 would improve diagnosis of osteoporosis and evaluation of treatment.