Assessment of Thermal Osteonecrosis during Bone Drilling Using a Three-Dimensional Finite Element Model.

Bone drilling is a common procedure used to create pilot holes for inserting screws to secure implants for fracture fixation. However, this process can increase bone temperature and the excessive heat can lead to cell death and thermal osteonecrosis, potentially causing early fixation failure or complications. We applied a three-dimensional dynamic elastoplastic finite element model to evaluate the propagation and distribution of heat during bone drilling and assess the thermally affected zone (TAZ) that may lead to thermal necrosis. This model investigates the parameters influencing bone temperature during bone drilling, including drill diameter, rotational speed, feed force, and predrilled hole. The results indicate that our FE model is sufficiently accurate in predicting the temperature rise effect during bone drilling. The maximum temperature decreases exponentially with radial distance. When the feed forces are 40 and 60 N, the maximum temperature does not exceed 45 °C. However, with feed forces of 10 and 20 N, both the maximum temperatures exceed 45 °C within a radial distance of 0.2 mm, indicating a high-risk zone for potential thermal osteonecrosis. With the two-stage drilling procedure, where a 2.5 mm pilot hole is predrilled, the maximum temperature can be reduced by 14 °C. This suggests that higher feed force and rotational speed and/or using a two-stage drilling process could mitigate bone temperature elevation and reduce the risk of thermal osteonecrosis during bone drilling.

Cyclic Stability of Locking Plate Augmented with Intramedullary Polymethyl Methacrylate (PMMA) Strut Fixation for Osteoporotic Humeral Fractures: A Biomechanical Study.

The locking plate may provide improved fixation in osteoporotic bone; however, it has been reported to fail due to varus collapse or screw perforation of the articular surface, especially in osteoporotic bone with medial cortex comminution. Using bone graft as an intramedullary strut together with plate fixation may result in a stronger construct. However, the drawbacks of bone grafts include limited supply, high cost, and infection risk. PMMA (so-called bone cement) has been widely used for implant fixation due to its good mechanical properties, fabricability, and biocompatibility. The risk of donor-site infection and the drawbacks of allografting may be overcome by considering PMMA struts as alternatives to fibular grafts for humeral intramedullary grafting surgeries. However, the potential effects of intramedullary PMMA strut on the dynamic behaviour of osteoporotic humerus fractures remain unclear. This study aimed to investigate the influence of an intramedullary PMMA strut on the stability of unstable proximal humeral fractures in an osteoporotic synthetic model. Two fixation techniques, a locking plate alone (non-strut group) and the same fixation augmented with an intramedullary PMMA strut (with-strut group), were cyclically tested in 20 artificial humeral models. Axially cyclic testing was performed to 450 N for 10,000 cycles, intercyclic motion, cumulated fragment migration, and residual deformation of the constructs were determined at periodic cyclic intervals, and the groups were compared. Results showed that adding an intramedullary PMMA strut could decrease 1.6 times intercyclic motion, 2 times cumulated fracture gap migration, and 1.8 times residual deformation from non-strut fixation. During cycling, neither screw pull-out, cut-through, nor implant failure was observed in the strut-augmented group. We concluded that the plate-strut mechanism could enhance the cyclic stability of the fixation and minimize the residual displacement of the fragment in treating osteoporotic proximal humeral unstable fractures. The PMMA strut has the potential to substitute donor bone and serve as an intramedullary support when used in combination with locking plate fixation. The intramedullary support with bone cement can be considered a solution in the treatment of osteoporotic proximal humeral fractures, especially when there is medial comminution.

Causal influence of sleeping phenotypes on the risk of coronary artery disease and sudden cardiac arrest: A Mendelian randomization analysis.

OBJECTIVES: To assess the causal influence of sleep and circadian traits on coronary artery disease and sudden cardiac arrest with adjustment for obesity through a two-sample Mendelian randomization study. METHODS: We used summary statistics of 5 sleep and circadian traits for genome-wide association studies, including chronotype, sleep duration, long sleep (≥9 h a day), short sleep (<7 h a day), and insomnia (sample size range: 237,622-651,295). Coronary artery disease genome-wide association studies with 60,801 cases and 123,504 controls, sudden cardiac arrest genome-wide association studies with 3939 cases and 25,989 controls, and obesity genome-wide association studies with 806,834 individuals were also used. Multivariable Mendelian randomization was performed to estimate the causality. RESULTS: After adjusting for obesity, genetically predicted short sleep (odds ratio = 1.87 and p = .02), and genetically predicted insomnia (odds ratio = 1.17 and p = .001) were causally associated with increased odds of coronary artery disease. Genetically predicted long sleep (odds ratio = 0.06 and p = .02) and genetically predicted longer sleep duration (odds ratio = 0.36 for per-hour increase in sleep duration and p = .0006) were causally associated with decreased odds of sudden cardiac arrest. CONCLUSIONS: The findings of this Mendelian randomization study indicate that insomnia and short sleep contribute to the development of coronary artery disease, whereas a longer sleep duration protects from sudden cardiac arrest, independent of the influence of obesity. The mechanisms underlying these associations warrant further investigation.

Alcohol abuse may increase the risk of autoimmune connective tissue disease: a nationwide population-based cohort study.

Objectives: Altered immune and inflammatory responses resulting from alcohol abuse have been implicated in increasing the risk of autoimmune connective tissue disease (ACTD). However, limited research has been conducted on this topic in the Asian population. Therefore, this study was undertaken to investigate and address this knowledge gap. Methods: Using data from Taiwan's National Health Insurance Research Database, we identified all patients with alcohol abuse between 2000 and 2017. We selected a comparison cohort without alcohol abuse, matching them in terms of age, sex, and index date at a 3:1 ratio. We collected information on common underlying comorbidities for analysis. Both cohorts were followed up until the diagnosis of ACTD or the end of 2018. Results: A total of 57,154 patients with alcohol abuse and 171,462 patients without alcohol abuse were included in the study. The age and sex distributions were similar in both cohorts, with men accounting for 89.8% of the total. After adjusting for underlying comorbidities, patients with alcohol abuse had a higher risk of developing ACTD [adjusted hazard ratio (AHR): 1.12, 95% confidence interval (CI): 1.01-1.25]. The stratified analysis revealed that this increased risk was specific to the male population. Additionally, besides alcohol abuse, liver disease, renal disease, coronary artery disease, and chronic obstructive pulmonary disease were identified as independent predictors for ACTD. Conclusion: This study demonstrates that alcohol abuse increases the risk of developing ACTD in the Asian population, particularly among men. Therefore, it is important to implement alcohol cessation, especially in individuals with liver disease, renal disease, coronary artery disease, and chronic obstructive pulmonary disease.

Association between osteoarthritis and urinary tract infection in older adults: A nationwide population-based cohort study.

Osteoarthritis (OA) may increase urinary tract infection (UTI) in older adults. However, this issue remains unclear. We identified 8599 older patients (≥65 years) with OA, and an equal number of older patients without OA, matched by age, sex, and index date from the Taiwan National Health Insurance Research Database between 2001 and 2005. Past histories, including UTI and underlying comorbidities, were included in the analyses. Comparisons for any UTI, ≥1 hospitalization for UTI, and ≥3 hospitalizations for UTI between the 2 cohorts by following up until 2015 were performed. In both cohorts, the percentages of age subgroups were 65-74 years (65.7%), 75-84 years (30.1%), and ≥85 years (4.2%). The male sex was 42.4%. Patients with OA had an increased risk of any UTI compared with those without OA after adjusting for all past histories (adjusted hazard ratio [AHR]: 1.72; 95% confidence interval [CI]: 1.64-1.80). Compared with patients without OA, patients with OA also had an increased risk of ≥1 hospitalization for UTI and ≥3 hospitalizations for UTI (AHR: 1.13; 95% CI: 1.06-1.19 and AHR: 1.25; 95% CI: 1.13-1.38, respectively). In addition to OA, age 75-84 years, female sex, history of UTI, benign prostatic hyperplasia, indwelling urinary catheter, cerebrovascular disease, dementia, and urolithiasis were independent predictors for any UTI. This study showed that OA was associated with UTI in older adults. We suggest appropriately managing OA and controlling underlying comorbidities to prevent subsequent UTI.

Risk of acute mesenteric ischemia in patients with diabetes: A population-based cohort study in Taiwan.

BACKGROUND AND AIMS: Diabetes is a common and complex endocrine disorder that often results in hyperglycemia, which has been strongly implicated in several cardiovascular and cerebrovascular events that cause disability. Acute mesenteric ischemia (AMI) is a vascular emergency with high mortality rates. We conducted a population-based cohort study that utilizes data from medical claims databases to investigate whether diabetes increases the risk of AMI. METHODS: Using claims data from Taiwan's National Health Insurance program, 66,624 diabetic patients were enrolled from 1998 to 2009, and a comparison group of 266,496 individually matched subjects without diabetes was selected. The two groups were followed up until diagnosis of AMI, death, or the end of 2011. Incidence rates of AMI were assessed in both groups. Cox proportional hazards models were used to estimate the hazard ratios of diabetes for AMI. RESULTS: The diabetes cohort had a higher incidence rate than the comparison cohort for AMI (0.56 vs. 0.29 per 1,000 person-years). After adjusting for sex, age, comorbidity, and health system utilization, the adjusted hazard ratio of diabetes was 1.32 (95% confidence interval 1.11-1.56) for AMI. The risk of AMI associated with diabetes was greater in men (adjusted hazard ratio = 1.48, 95% confidence interval 1.17-1.87) than in women (adjusted hazard ratio = 1.17, 95% confidence interval 0.92-1.49). CONCLUSIONS: There was an increased risk of AMI in patients with diabetes. However, further research is required to understand whether this association is causal or due to a common set of risk factors.