PubMed · 9144354
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S J Silverberg, J P Bilezikian. 1997. Primary hyperparathyroidism: still evolving?. https://doi.org/10.1359/jbmr.1997.12.5.856
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BACKGROUND: In a great many of observational studies, whether there is a relevance of resistin levels on bone mineral density (BMD) and fracture occurrence has been inconsistently reported, and the causality is unclear. METHODS: We aim to assess the resistin levels on BMD and fracture occurrence within a Mendelian randomization (MR) analysis. Exposure and outcome data were derived from the Integrative Epidemiology Unit (IEU) Open genome wide association studies (GWAS) database. Screening of instrumental variables (IVs) was performed subject to conditions of relevance, exclusivity, and independence. Inverse variance weighting (IVW) was our primary method for MR analysis based on harmonized data. Weighted median and MR-Egger were chosen to evaluate the robustness of the results of IVW. Simultaneously, heterogeneity and horizontal pleiotropy were also assessed and the direction of potential causality was detected by MR Steiger. Multivariable MR (MVMR) analysis was used to identify whether confounding factors affected the reliability of the results. RESULTS: After Bonferroni correction, the results showed a suggestively positive causality between resistin levels and total body BMD (TB-BMD) in European populations over the age of 60 [β(95%CI): 0.093(0.021, 0.165), P = 0.011]. The weighted median [β(95%CI): 0.111(0.067, 0.213), P = 0.035] and MR-Egger [β(95%CI): 0.162(0.025, 0.2983), P = 0.040] results demonstrate the robustness of the IVW results. No presence of pleiotropy or heterogeneity was detected between them. MR Steiger supports the causal inference result and MVMR suggests its direct effect. CONCLUSIONS: In European population older than 60 years, genetically predicted higher levels of resistin were associated with higher TB-BMD. A significant causality between resistin levels on BMD at different sites, fracture in certain parts of the body, and BMD in four different age groups between 0-60 years of age was not found in our study.
STUDY DESIGN: An investigation of the relation between intraoperative insertional torque of pedicle screws, bone mineral density of the vertebra, and development of screw loosening in vivo. OBJECTIVES: To determine the usefulness of intraoperative measurement of the insertional torque of pedicle screws. SUMMARY OF BACKGROUND DATA: Some biomechanical studies have demonstrated that the insertional torque is highly correlated with bone mineral density and the stability of pedicle screws in vitro. METHODS: Pedicle screw fixation was performed with posterior lumbar interbody fusion in 62 consecutive patients. The mean age of the patients at the time of surgery was 58 years. The insertional torque of pedicle screws was measured intraoperatively in all patients. The mean follow-up period was 2.7 years. RESULTS: The mean insertional torque was 1.28 +/- 0.37 Nm in patients with screw loosening and 1.50 +/- 0. 40 Nm in patients without the problem. The mean insertional torque in patients with compression fractures in the upper vertebra adjacent to the fixed segment was 0.83 +/- 0.23 Nm. There was no significant difference between the mean insertional torque in patients with screw loosening and those without the condition. The mean insertional torque in patients without screw loosening was significantly greater than in patients with compression fractures (P < 0.01). A high correlation was found between insertional torque and bone mineral density (P < 0.01). CONCLUSIONS: Although a high correlation was found between the insertional torque of pedicle screws and bone mineral density in vivo, the insertional torque could not objectively predict screw loosening.
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