Local heat generation during screw insertion into diaphyseal bone: a biomechanical study on different conditions (e.g. screw type, material, mode of insertion).

BACKGROUND: The implantation of screws is a standard procedure in musculoskeletal surgery. Heat can induce thermal osteonecrosis, damage the bone and lead to secondary problems like implant loosening and secondary fractures. The aim of this study was to investigate whether screw insertion generates temperatures that can cause osteonecrosis. METHODS: We measured the temperature of twenty human femur diaphysis in a total of 120 measurements, while screws of different material (stainless steel and titanium alloy) and different design (locking and cortex screw) were inserted in three different screwing modes (manual vs. machine screwing at full and reduced rotational speed) with 6 thermocouples (3 cis and 3 trans cortex). Each was placed at a depth of 2 mm with a distance of 1.5 mm from the outer surface of the screw. RESULTS: The screw design (cortical > locking), the site of measurement (trans-cortex > cis-cortex) and the type of screw insertion (hand insertion > machine insertion) have an influence on the increase in bone temperature. The screw material (steel > titanium), the site of measurement (trans-cortex > cis-cortex) and the type of screw insertion (machine insertion > hand insertion) have an influence on the time needed to cool below critical temperature values. The combination of the two parameters (maximum temperature and cooling time), which is particularly critical for osteonecrosis, is found only at the trans-cortex. CONCLUSION: Inserting a screw hast the potential to increase the temperature of the surrounding bone tissue above critical values and therefore can induce osteonecrosis. The trans-cortex is the critical area for the development of temperatures above the osteonecrosis threshold, making effective cooling by irrigation difficult. It would be conceivable to cool the borehole with cold saline solution before inserting the screw or to cool the screw in cold saline solution. If possible, insertion by hand should be considered.

Medical education too: sexual harassment within the educational context of medicine - insights of undergraduates.

BACKGROUND: Assessment of the presence and characteristics of sexual harassment in academic medicine is a global issue. Only limited international data are available so far. METHODS: Aim: To assess the extent of sexual harassment and identify the perpetrators in the student population of the medical school of Münster, Germany. A survey was undertaken, using the Medical Women's International Association sexual harassment questionnaire translated into German. The anonymous online questionnaire was sent as a link to all medical undergraduates at Münster Medical School via a mailing list between 1 October and 30 November 2018. Identifying or potentially identifying data were not collected. Data were analysed by descriptive statistical methods such as categorical variables. Baseline characteristics, e.g. answers by male or female medical students, were correlated with their individual sexual harassment experiences and perpetrator groups by means of univariate analysis. RESULTS: A total of 2162 medical students were asked to participate, with 623 (28.8%) completing the survey. Sexual harassment is a significant issue among medical students at Münster Medical School with over half (58.9%) of all undergraduates being exposed to sexually harassing behaviour. In total, 31.8% of all participants reported having experienced unwanted physical sexual contact such as unwanted physical touching, with 87.6% of the victims being female. Overall, 41.3% personally experienced verbal sexual harassment of which 87.4% were female. Furthermore, 8.5% of undergraduates faced forced sexual contact such as oral, anal or vaginal penetration, intercourse and rape, with all victims being female. Perpetrators in these cases were mostly male medical superiors (7.0%) and male patients (18.3%). In general, most perpetrators were patients, followed by medical superiors and educators, and less frequently by colleagues. CONCLUSIONS: Sexual harassment in medical education and the medical workplace is a significant problem in a German medical school. Most students experiencing sexual harassment are females. Female students also experience the more serious forms of sexual harassment more often.