Correlation between bone density and lumbar disc degeneration in postmenopausal women

English Keywords:Disc degeneration  Bone mineral density  Menopause  Women

English Abstract:

  【Abstract】 Objectives: To investigate the relationship between bone mineral density(BMD) and lumbar disc degeneration in postmenopausal women. Methods: A total of 229 postmenopausal female patients with low back pain were retrospectively selected from the outpatient and inpatient departments of spine surgery in our hospital from December 2017 to December 2018. Patients′ demographics data such as age, height, weight, diabetes history, hypertension history, drinking history and smoking history were recorded. BMD of the lumbar spine(L1-L4) and mean hip were obtained by dual-energy X-ray, and T values were recorded. Each patient received lumbar magnetic resonance imaging(MRI) examination. Participants with a T-score of ≤-2.5 were diagnosed with osteoporosis, those with a T score of -2.5 to -1.0 were diagnosed with osteopenia, and those with a T-score of ≥-1.0 were considered normal. According to the BMD values, all patients were divided into osteoporosis(n=78), osteopenia(n=73) and normal(n=78) groups. The degree of lumbar disc degeneration at each level was scored using Pfirrmann grading system to correlate with lumbar and hip BMD. Covariance and Spearman correlation analysis were used to analyze the relationship between lumbar and hip BMD and lumbar disc degeneration. Results: The age of the osteoporosis group was significantly higher than that of the normal group(67.17±9.99 years vs 55.29±12.35 years, P＜0.05) and so was that of osteopenia group than normal group(65.66±10.71 years vs 55.29±12.35 years, P＜0.05). The body mass index(BMI) of osteoporosis group was lower than that of the normal group(23.38±2.37 vs 24.72±2.96, P<0.05). There was no significant difference in other general data among the groups(P>0.05). In the upper lumbar spine(L1, L2), the degree of lumbar disc degeneration in the osteoporosis group was lower than that in the normal group (2.24±0.82 vs 2.60±0.95, 2.79±0.95 vs 3.18±0.94, P＜0.05), and no significant difference was found between osteopenia and osteoporosis groups(P>0.05). There was no significant difference in the degree of disc degeneration between the lower lumbar spine(L3, L4) and the hip groups with different BMD. BMD of each lumbar vertebra was positively correlated with the degree of lumbar disc degeneration (L1: r=0.185; L2: r=0.157; L3: r=0.180; L4: r=0.132; L1-L4: r=0.180; P＜0.05), while there was no correlation between hip BMD and lumbar disc degeneration. Conclusions: There is a positive correlation between lumbar disc degeneration and lumbar BMD in postmenopausal women, and higher lumbar BMD were associated with more severe LDD. It is necessary to take a further examination of lumbar spine using CT or MRI. Hip BMD may be a more reliable measurement for diagnosing osteoporosis.