Differences in External and Internal Cortical Strain with Prosthesis in the Femur

The contact between a femoral stem prosthesis and the internal surface of the cortical bone with the stress in the interface is of crucial importance with respect to loosening. However, there are no reports of strain patterns at this site, and the main aim of the current study was to investigate differences of internal and external cortical strain in the proximal femur after insertion of a stem prosthesis. The external cortical strain of a human cadaveric femur was measured with strain gauges before and after implantation of a stem prosthesis. By use of optical fibres embedded longitudinally in the endosteal cortex, deformations at the implant–internal cortex interface could also be measured. The main external deformation during loading of the intact femur occurred as compression of the medial cortex; both at the proximal and distal levels. The direction of the principal strain on the medial and lateral aspects was close to the longitudinal axis of the bone. After resection of the femoral neck and insertion of a stem prosthesis, the changes in external strain values were greatest medially at the proximal level, where the magnitude of deformation in compression was reduced to about half the values measured on the intact specimen. Otherwise, there were rather small changes in external principal strain. However, by comparing vertical strain in the external and internal cortex of the proximal femur, there were great differences in values and patterns at all positions. The transcortical differences in strain varied from compression on one side to distraction on the other and vice versa in some of the positions with a correlation coefficient of 0.07. Our results show that differences exist between the external and internal cortical strain when loading a stem prosthesis. Hence, strain at the internal cortex does not correspond and can not be deducted from measured strain at the external cortex

Strategic analysis and valuation of Bodø/Glimt

Masteroppgave i finansiering og investering - Nord universitet 202

Topical moistening of mastectomy wounds with diluted tranexamic acid to reduce bleeding: randomized clinical trial

Background: Topical administration of tranexamic acid (TXA) may be an alternative to intravenous administration to reduce bleeding with a lower risk of systemic adverse events. The aim of this study was to investigate whether moistening a surgical wound with TXA before closure, leaving a thin film of drug only, would reduce postoperative bleeding. Methods: This was a two‐centre, stratified, parallel‐group, placebo‐controlled, double‐blind RCT. Patients undergoing mastectomy with or without axillary lymph node clearance were randomized 1 : 1 to moistening of wound surface before closure with either 25 mg/ml TXA or 0·9 per cent sodium chloride (placebo). The primary endpoint was postoperative bleeding as measured by drain production in the first 24 h. Secondary endpoints were early haematoma, total drain production, postoperative complications and late aspirations of seroma within 3 months. Results: Between 1 January 2016 and 31 August 2018, 208 patients were randomized. Two patients were converted to a different surgical procedure at surgery, and four did not receive the intervention owing to technical error. Thus, 202 patients were included in the study (101 in the TXA and 101 in the placebo group). TXA reduced mean drain production at 24 h (110 versus 144 ml; mean difference 34 (95 per cent c.i. 8 to 60) ml, P = 0·011). One patient in the TXA group had early haematoma compared with seven in the placebo group (odds ratio (OR) 0·13 (95 per cent c.i. 0·02 to 1·07); P = 0·057). There was no significant difference in postoperative complications between TXA and placebo (13 versus 10; OR 1·11 (0·45 to 2·73), P = 0·824) or need for late seroma aspirations (79 versus 67 per cent; OR 1·83 (0·91 to 3·68), P = 0·089). Conclusion Moistening the wound with TXA 25 mg/ml before closure reduces postoperative bleeding within the first 24 h in patients undergoing mastectomy. Registration number: NCT02627560 (https://clinicaltrials.gov)

Block scheduling at magnetic resonance imaging labs

This paper considers a tactical block scheduling problem at a major Norwegian hospital. Here, specific patient groups are reserved time blocks for scanning at a heterogeneous set of Magnetic Resonance Imaging (MRI) labs. The time blocks consist of several time slots, and one or more patients from the same group are scanned in a block. A total weekly number of time slots for each specific patient group is given through demand forecast and negotiations, and several restrictions apply to the allocation of time blocks. Only part of the week is allocated to blocks for the specific patient groups. The rest is classified as open time. Thus, the MRI block scheduling problem consists of finding a cyclic weekly plan where one or more time blocks are to be allocated to each specific patient group, by deciding the day, start time and length, to minimise unfavourable patient group allocations, as well as allocations of open time. For the problem, we propose an integer programming model with an objective function that combines penalties for allocating time blocks to patient groups at unfavourable time slots and labs, and rewards for advantageous positioning of open time slots. The aim of the optimisation model is to facilitate the coordination of the MRI resources between the hospital departments, that are responsible for the specific patient groups, to achieve a fair distribution of time slots to the specific patient groups and open time blocks. The computational study is based on the real problem as well as artificially generated instances. Real-sized instances for our case hospital can be solved in short time. We illustrate how the model can be used to produce Pareto optimal solutions, and how these solutions can provide the decision makers with managerial insight