PubMed · 164839
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J Dequeker. 1975. Bone and ageing.. https://doi.org/10.1136/ard.34.1.100
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BACKGROUND: Researchers have hypothesized that bone mineral density (BMD) may be influenced by chemical compounds such as caffeine, phytoestrogen, fluoride, and many compounds that are contained in tea extracts. Hence, the relationship between habitual tea consumption and BMD is an interesting issue. METHODS: Based on an epidemiological survey, we enrolled 497 men and 540 women, 30 years and older, in our study. All subjects were questioned about their habit of tea consumption and other lifestyle characteristics by means of a structured questionnaire. Dual-energy x-ray absorptiometry was used to measure the BMD of the total body, lumbar spine (L1-L4), hip neck, and Ward triangle regions. RESULTS: Five hundred two subjects (48.4%) were habitual tea drinkers, with a mean duration of tea consumption of approximately 10 years. Compared with nonhabitual tea drinkers, subjects with habitual tea consumption of 6 to 10 years showed higher lumbar spine BMDs, and those with consumption of more than 10 years showed the highest BMDs of all measured regions. Under the multiple stepwise regression models, sex, age, body mass index, total physical activity, and habit of tea consumption were the major significant variables for the different BMD regions. Regarding the behavioral characteristics of tea consumption, the duration of tea consumption was the only independent determinant for the BMDs. CONCLUSION: Habitual tea consumption, especially for more than 10 years, has significant beneficial effects on BMD of the total body, lumbar spine, and hip regions in adults.
STUDY DESIGN: A biomechanical study of human cadaveric sacra using insertional torque and bone mineral density was conducted to determine the optimal sagittal trajectory of S1 pedicle screws. OBJECTIVE: To measure the maximal insertional torque of sacral promontory versus bicortical pedicle screw fixation. SUMMARY OF BACKGROUND DATA: Fixation of instrumentation to the sacrum is commonly accomplished using S1 pedicle screws, with previous studies reporting biomechanical advantages of bicortical over unicortical S1 screws. The biomechanical effect of bicortical screws (paralleling the endplate) versus screws directed into the apex of the sacral promontory is unknown. METHODS: For this study, 10 fresh frozen cadaver sacra were harvested and evaluated with dual-energy radiograph absorptiometry to assess bone mineral density. Matched 7.5-mm monoaxial stainless steel pedicle screws then were randomly assigned by side (left versus right) and placed bicortically or into the apex of the sacral promontory under direct visualization. Maximum insertional torque was recorded for each screw revolution with a digital torque wrench (TQJE1500, Snap-On Tools, Kenosha, WI). RESULTS: Maximum bicortical S1 screw insertional torque averaged 5.22 +/- 0.83 inch-pounds, as compared with the maximum sacral promontory S1 screw insertional torque of 10.34 +/- 1.94 inch-pounds. This resulted in a 99% increase in maximum insertional torque (P = 0.005) using the "tricortical" technique, with the screw directed into the sacral promontory. Mean bone mineral density was 940 +/- 0.25 mg/cm2 (range, 507-1428 mg/cm2). The bone mineral density correlated with maximal insertional torque for the sacral promontory technique (r = 0.806; P = 0.005), but not for the bicortical technique (r = 0.48; P = 0.16). CONCLUSIONS: The screws directed into the apex of the sacral promontory of the S1 pedicle resulted in an average 99% increase in peak insertional torque (P = 0.005), as compared with bicortical S1 pedicle screw fixation. Tricortical pedicle screw fixation correlates directly with bone mineral density.
Total body bone mineral content (TBBMC) was measured by dual energy x-ray absorptiometry in a cross-sectional study of 51 prepubertal HIV-infected children and 262 healthy prepubertal children aged 4.2 to 14.7 years. The mean TBBMC +/- SD was lower in HIV-positive children than in HIV-negative controls (955 +/- 325 vs. 1,106 +/- 273 g, respectively; p =.0006). Reductions in TBBMC remained in the HIV-positive group after adjusting for age, sex, and race by analysis of covariance (p <.001). Differences in TBBMC between HIV-positive and HIV-negative groups persisted when height and weight were also accounted for in the analysis (p =.027). The magnitude of the difference in TBBMC between the groups increased with age. In the HIV-positive group, no associations were observed between TBBMC and use of a protease inhibitor, duration of treatment with antiretroviral medications, viral load, or CD4 cell count. TBBMC is decreased in HIV-infected children. As a result of compromised bone mineral accrual, HIV-infected children may be at increased risk for osteoporosis and related complications.