Locked plate constructs are not necessarily stiffer than nonlocked constructs: A biomechanical investigation of locked versus nonlocked diaphyseal fixation in a human cadaveric model of nonosteoporotic and osteoporotic distal femoral fractures.

Objectives: The objective of this study was to compare the biomechanical properties of locked and nonlocked diaphyseal fixation in a model of distal femur fractures using osteoporotic and nonosteoporotic human cadaveric bone. Methods: A supracondylar osteotomy was created to mimic a fracture (OTA/AO 33A3) in osteoporotic (n = 4) and nonosteoporotic (n = 5) cadaveric distal femurs. The left and right femurs of each pair were instrumented with a distal femoral locking plate and randomly assigned to have diaphyseal fixation with either locked or nonlocked screws. The construct was cyclically axially loaded, and construct stiffness and load to failure were evaluated. Results: In osteoporotic bone, locked constructs were more stiff than nonlocked constructs (mean 143 vs. 98 N/mm when all time points combined, P < 0.001). However, in nonosteoporotic bone, locked constructs were less stiff than nonlocked constructs (mean 155 N/mm vs. 185 N/mm when all time points combined, P < 0.001). In osteoporotic bone, the average load to failure was greater in the locked group than in the nonlocked group (mean 1159 vs. 991 N, P = 0.01). In nonosteoporotic bone, the average load to failure was greater for the nonlocked group (mean 1348 N vs. 1214 N, P = 0.02). Bone mineral density was highly correlated with maximal load to failure (R2 = 0.92, P = 0.001) and stiffness (R2 = 0.78, P = 0.002) in nonlocked constructs but not in locked constructs. Conclusions: Contrary to popular belief, locked plating constructs are not necessarily stiffer than nonlocked constructs. In healthy nonosteoporotic bone, locked diaphyseal fixation does not provide a stiffer construct than nonlocked fixation. Bone quality has a profound influence on the stiffness of nonlocked (but not locked) constructs in distal femur fractures.

Safety of an inactivated SARS-CoV-2 vaccine among healthcare workers in China.

Background: Although the inactivated SARS-CoV-2 vaccine (CoronaVac) has undergone preclinical tests and clinical trials evaluating its efficacy and safety, few data have been reported in the post-licensure real-world setting. We aimed to assess the safety of the vaccine among healthcare workers.Methods: A self-administered online survey on monitoring adverse reactions post vaccination was conducted among the staff who worked at and were vaccinated in a tertiary hospital in Taizhou, China, from February 24 to 7 March 2021. A total of 1526 subjects responded to the questionnaire when they received an e-mail or an e-poster on WeChat.Results: The incidences of overall adverse reactions after the first and second injections were 15.6% (238/1526) and 14.6% (204/1397), respectively. The most common adverse reaction was localized pain at the injection site, with an incidence of 9.6% and 10.7% after each dose, accounting for 61.8% and 73.0% of adverse reactions, respectively. Fatigue, muscle pain, and headache were the most common systemic adverse reactions.Conclusions: These findings implied that the inactivated CoronaVac vaccine has an acceptable safety profile among healthcare workers due to the low incidence of self-reported adverse reactions. This may boost public confidence in nationwide mass vaccination campaigns.

Locking Hole Inserts: Effect of Insertion Torque on Fatigue Performance and Insert Loosening in Locking Plates.

OBJECTIVES: To evaluate the effect of locking hole inserts (LHIs) and their insertion torque on locking plate fatigue life. METHODS: Eighteen standard 3.5-mm locking plates were instrumented with LHIs (Smith & Nephew, Memphis, TN) of 1.70 or 3.96 Nm insertion torque, or without LHIs, whereas eleven 4.5-mm locking plates were instrumented with LHIs at 3.96 Nm insertion torque or without LHIs. Plates were cyclically loaded to failure (ie, plate fracture) in four-point bending. Number of cycles to plate failure were measured. RESULTS: The 3.5-mm plates with 1.70 Nm LHI insertion torque had a 52% increase in cycles to failure compared with plates without LHIs (114,300 ± 23,680 vs. 75,487 ± 15,746 cycles; P = 0.01). Increasing insertion torque to 3.96 Nm led to a further increase of 36% in fatigue life (155,177 ± 32,493 cycles; P = 0.02) and a 106% increase compared with plates without LHIs (P = 0.001). The 4.5-mm plates with 3.96 Nm insertion torque had a 48% increase in cycles to failure when compared with plates without LHIs (74,369 ± 10,181 vs. 50,214 ± 5544 cycles; P = 0.001). CONCLUSIONS: LHIs significantly extend plate fatigue length, which would be advantageous in the setting of delayed fracture healing. We recommend the use of LHIs in round locking holes over bony gaps whenever possible; however, we recognize that these findings are limited to implants manufactured by Smith & Nephew.

[Correlation of delta18O in precipitation and moisture sources at Yunfu, Western Guangdong Province, China].

Fifty-nine samples of atmospheric precipitation were collected at Yunfu, Western Guangdong province during the period of April 5, 2005 to April 1, 2006 and their oxygen isotopic compositions were analyzed. Results show that delta18O values range from -12.47 per thousand to -0.18 per thousand with an average of -4.91 per thousand; the delta18O values of summer and autumn (from May to September) are relatively lower, ranging from -10.00 per thousand to -5.00 per thousand with an average of -6.30 per thousand; the delta18O values of winter and spring (from October to next April) are relatively higher, ranging from - 3.00 per thousand to - 1.00 per thousand with an average of - 2.20 per thousand. These delta18O values have relatively marked negative correlation with the corresponding temperatures and water vapour pressure and their coefficients are both -0.60; but they have had negative correlation with the precipitation amount, the coefficient is -0.33. Comparing with the monthly delta18O value of Guangzhou atmospheric precipitation, those of Yunfu City is relatively lower, maybe the reason is that Yunfu City is influenced by stronger South-West Asian Monsoon. The results of HYSPLIT back trajectory analysis indicated that the differences of delta18O values are determined by different water vapour sources during the pre-rainy season (from April to June), post-rainy season (from July to September) and non-rainy season (from October to next April), so the delta18O values can be considered as an indicator of denoting their water vapour sources, relatively higher delta18O values denote the water vapour sources are denaturalized tropical hot air mass located in the subtropical sea areas (including the South China Sea), western Pacific Ocean; relatively lower delta18O values indicate denaturalized tropical hot air mass from the India Ocean and Bengal Gulf.