A computational framework for crack propagation in spatially heterogeneous materials.

This paper presents a mathematical formulation and numerical modelling framework for brittle crack propagation in heterogeneous elastic solids. Such materials are present in both natural and engineered scenarios. The formulation is developed in the framework of configurational mechanics and solved numerically using the finite-element method. We show the methodology previously established for homogeneous materials without the need for any further assumptions. The proposed model is based on the assumption of maximal dissipation of energy and uses the Griffith criterion; we show that this is sufficient to predict crack propagation in brittle heterogeneous materials, with spatially varying Young's modulus and fracture energy. Furthermore, we show that the crack path trajectory orientates itself such that it is always subject to Mode-I. The configurational forces and fracture energy release rate are both expressed exclusively in terms of nodal quantities, avoiding the need for post-processing and enabling a fully implicit formulation for modelling the evolving crack front and creation of new crack surfaces. The proposed formulation is verified and validated by comparing numerical results with both analytical solutions and experimental results. Both the predicted crack path and load-displacement response show very good agreement with experiments where the crack path was independent of material heterogeneity for those cases. Finally, the model is successfully used to consider the real and challenging scenario of fracture of an equine bone, with spatially varying material properties obtained from CT scanning. This article is part of a discussion meeting issue 'A cracking approach to inventing new tough materials: fracture stranger than friction'.

Correction to: The ESSKA-AFAS international consensus statement on peroneal tendon pathologies.

Unfortunately, the spelling of the names Daniel Haverkamp and Ákos Kynsburg were incorrect in the original online publication of the article.

The ESSKA-AFAS international consensus statement on peroneal tendon pathologies.

INTRODUCTION: Peroneal tendon injuries are a significant cause of lateral ankle symptoms in the active population. Accurate diagnosis and prompt treatment is important for minimizing the risk of long-term sequelae associated with chronic peroneal tendinopathy. Although several studies have been published on diagnostic strategies and treatment outcomes, there is no consensus on the optimal management of peroneal tendon pathologies. PURPOSE: The purpose of this ESSKA-AFAS consensus statement was to conduct an international and multidisciplinary agreed guideline on management of patients with peroneal tendon pathologies. METHODS: Using the Nominal Group Technique, a panel comprised of sixteen specialists spanning nine countries was convened by the ESSKA-AFAS board. In preparation for the meeting, relevant questions were identified and supported by a systematic literature search. During the meeting, the panel members gave presentations on each question, and the evidence supporting each subject was then vetted by open discussion. Statements were thereafter adjusted on the basis of the discussion and voted upon to determine consensus using a 0-10 range Likert scale. Agreement was confirmed when a mean score of at least 7.5 was reached. CONCLUSION: This ESSKA-AFAS consensus statement on the optimal management of peroneal tendon pathologies is the result of international and multidisciplinary agreement combined with a systematic review of the literature. LEVEL OF EVIDENCE: V.

Searching for consensus in the approach to patients with chronic lateral ankle instability: ask the expert.

PURPOSE: The purpose of this study is to propose recommendations for the treatment of patients with chronic lateral ankle instability (CAI) based on expert opinions. METHODS: A questionnaire was sent to 32 orthopaedic surgeons with clinical and scientific experience in the treatment of CAI. The questions were related to preoperative imaging, indications and timing of surgery, technical choices, and the influence of patient-related aspects. RESULTS: Thirty of the 32 invited surgeons (94%) responded. Consensus was found on several aspects of treatment. Preoperative MRI was routinely recommended. Surgery was considered in patients with functional ankle instability after 3-6 months of non-surgical treatment. Ligament repair is still the treatment of choice in patients with mechanical instability; however, in patients with generalized laxity or poor ligament quality, lateral ligament reconstruction (with grafting) of both the ATFL and CFL should be considered. CONCLUSIONS: Most surgeons request an MRI during the preoperative planning. There is a trend towards earlier surgical treatment (after failure of non-surgical treatment) in patients with mechanical ligament laxity (compared with functional instability) and in high-level athletes. This study proposes an assessment and a treatment algorithm that may be used as a recommendation in the treatment of patients with CAI. LEVEL OF EVIDENCE: V.

Advanced clinical practice and nurse-led clinics: a time to progress.

This article discusses the evolving role of advanced clinical practitioners in outpatient clinics and investigates required competency and governance and how this translates into patient care. Until recently, there has been little clear guidance in terms of how to cultivate and develop staff to the level of practice required for autonomous management of the patient pathway. This has been variable, dependent on the employing organisation and the enthusiasm for advanced practice at a senior level. The current frameworks and competency documents available are identified and how the competent practitioner can provide safe, effective care. The authors use their own practice within gynaecology as an example.

Review of non-medical prescribing among acute and community staff.

All employers of non-medical prescribers (NMPs) have a duty to ensure they remain competent and current, and have access to relevant continuing professional development as identified through their staff appraisals. This article describes a survey that was undertaken to evaluate non-medical prescribing in one trust that operates an acute district hospital and community services. Five themes emerged from the results: prescribing activity, patient safety, effect of non-medical prescribing on care, workforce planning and organisational support. The findings also suggested that most NMPs surveyed were compliant with local and national policy. Non-compliance was addressed through line manager intervention. Support for NMPs must be addressed at organisational level to ensure safety of all stakeholders.

Evaluating the forces involved in bubble management in DMEK surgery: mathematical and computational model with clinical implications.

PURPOSE: To model postoperative forces involved in Descemet membrane endothelial keratoplasty (DMEK) tissue adherence and bubble management, including the impact of surface tension on graft support, with a view towards clinical applications. SETTING: Tennent Institute of Ophthalmology, Glasgow, and James Watt School of Engineering, University of Glasgow, Glasgow, United Kingdom. DESIGN: Mathematical modelling and computer simulation. METHODS: Theoretical modelling of biphasic flow and interaction of gas, liquid and tissue within the anterior chamber for static horizontal scenario A (adherent DMEK with mobile bubble) and dynamic vertical scenario B (release of bubble due to pupil block following DMEK). RESULTS: The model assumed incompressibility for both fluids within realistically achievable pressure ranges. Cahn-Hilliard Navier-Stokes equations were discretised through the application of the Finite Element Method. Mathematical modelling and computer simulation showed bubble size, corneal curvature and force intensity influences surface tension support for DMEK tissue in scenario A. Scenario B demonstrated complex, uneven distribution of surface pressure on the DMEK graft during uncontrolled bubble release. Uneven pressure concentration can cause local tissue warping, with air/fluid displacement via capillary waves generated on the fluid-air interface adversely impacting DMEK support. CONCLUSIONS: We have quantitatively and qualitatively modelled the forces involved in DMEK adherence in normal circumstances. We have shown releasing air/gas can abruptly reduce DMEK tissue support via generation of large pressure gradients at the liquid/bubble/graft interfaces, creating negative local forces. Surgeons should consider these principles to reduce DMEK graft dislocation rates via optimised bubble size to graft size, longer acting bubble support and avoiding rapid decompression where possible.

Equine Suture Exostosis: A Review of Cases from a Multicenter Retrospective Study.

Suture exostosis is an intriguing and not uncommon pathology that has to be included in the differential diagnosis for horses with swelling of the head. Although several singular case reports have been published, no large case series is available. The aim of this study is to report a multicentric retrospective collection of suture exostosis cases. Data concerning horses with suture exostosis in the facial region were collected retrospectively. Information regarding breed, age, gender, history, imaging findings, initiated treatment, response to treatment and follow up was recorded. One hundred and five cases of various breeds were reported. Analysis revealed the cases could be grouped into four entities: 45 developed following sino-nasal surgery, 23 following trauma, seven with underlying sinus pathology and 25 idiopathic. Treatment consisted of sequestra removal, plate fixation, antimicrobial and anti-inflammatory drugs or no treatment. Whereas initial localized pain fades within few days or weeks, resolution or reduction of the swelling was obtained in most cases after 3 months to 1.5 years. The etiopathogenesis of suture exostosis seems to consist of different entities. Identification of an underlying cause, particularly the presence of a bone sequester and infection is important to speed up resolution and before concluding an idiopathic case. When performing sinusotomies, it is important to provide as little trauma as possible to the surgical site in order to prevent suture exostosis as a complication.

Using an open source observational tool to measure the influence of the doctor's consulting style and the computer system on the outcomes of the clinical consultation.

Computerization of general practice is an international phenomenon. Many of the Electronic Patient Record (EPR) systems have developed organically with considerable variation in their interface and functionality. Consequently they have differing impact on the clinical consultation. There is a dearth of tools available to study their impact on the consultation. The objective is to use ALFA to film and analyze a simulated clinical consultation. We used the ALFA (Activity Log File Aggregation) open source toolkit, to make video based observation and analysis of the computer mediated consultation. ALFA enables precise comparison of core elements of EPR systems. It allows multiple video channels including screen capture, data about computer use, and verbal interactions to be synchronized, timed and navigated through for analysis. The toolkit is free and can be downloaded under an open source license from www.biomedicalinformatics.info/alfa/. Its outputs, which include Unified Modelling Language (UML), provide the evidence-base for assessing the impact of the computer on the consultation the designing of EPR systems. ALFA has been used to compare different brands of primary care computer systems; nurse case-load selection and consultation in psychiatry.

The MyHealthRecord System Impacts on Patient Workflow in General Practices.

Digital health is widely believed to have vast potential in improving patient care. MyHealthRecord (MyHR) is a digital health information system which enables Australian citizens to access their health information centrally, making it available anywhere, at anytime. The aim of this study is to explore the adoption of MyHR in general practices in Victoria and understand its impacts. A qualitative case study research method was used to underpin this investigation. Ten general practices were engaged where MyHR was implemented/used. Detailed interviews with MyHR implementers were held and GPs were engaged in short interviews. Twenty observations were made during GP/patient consultations for health summary uploads. Findings indicate that the practice incentive payment (PIP) funding policy change encouraged the use of MyHR, but the adoption was limited to satisfy funding criteria. Change management was often extemporised. Health summary upload was a quick and easy process but was influenced by clinical system data quality and GP familiarity with the system. Community awareness and GP interest in MyHR was lacking. The conclusion is that MyHR was not well integrated in general practices nor the community. As a result, an improved engagement approach between healthcare organisations, the MyHR system operator and Australians is required.

A multidisciplinary approach to self care in chronic pelvic pain.

Chronic pelvic pain is one of the most difficult conditions encountered by health professionals working with women both in primary and secondary care. The cause is variable, and for some women a diagnosis is never determined. While it is acknowledged that it is a symptom and not a condition, many women and professionals continue to seek a cause and cure. It is contended that this client group is best supported by a multidisciplinary approach to symptom control that incorporates the skills of the gynaecologist, physiotherapist, nurse, psychologist and pain management specialist. This is often difficult to achieve within a resource-limited environment. An alternative approach is suggested using current resources, which provides patient education and support, thus empowering women to influence their health behaviours and situations.

Ten steps to managing change.

CHANGE MANAGEMENT is a prime requirement of management. Change is all around us, and is happening every day. To some, this is exciting; they find it thrilling to be part of the action and to keep up with trends. But, to others, it can be threatening or even frightening.

Ten steps to writing curriculum vitae covering letters.

As guides for recruiters, the covering letters of applicants' curricula vitae (CVs) can be almost as important as the CVs themselves. When applying for posts therefore, you should regard the writing of such letters as an opportunity to distinguish yourself from other candidates.

Ten steps to conducting a selection interview.

Many research studies show that predictions made at interviews often fail because of bias, failure to obtain the information required, or the inability to interpret information. To minimise these problems, a systematic approach to interviewing must be adopted.

The difficult patient.

A large percentage of any general practitioner's time is taken up by a small number of patients, the 'difficult' patient. These patients often have chronic, painful problems, and are unresponsive to traditional medical methods. By understanding the concepts of the patient centred clinical method, and looking beyond the traditional biological model of disease, an approach to these patients can be developed that is simple and enduring.

Information architecture considerations in designing a comprehensive tuberculosis enterprise system in Western Kenya.

Kenya ranks among the twenty-two countries that collectively contribute about 80% of the world's Tuberculosis cases; with a 50-200 fold increased risk of tuberculosis in HIV infected persons versus non-HIV hosts. Contemporaneously, there is an increase in mobile penetration and its use to support healthcare throughout Africa. Many are skeptical that such m-health solutions are unsustainable and not scalable. We seek to design a scalable, pervasive m-health solution for Tuberculosis care to become a use case for sustainable and scalable health IT in limited resource settings. We combine agile design principles and user-centered design to develop the architecture needed for this initiative. Furthermore, the architecture runs on multiple devices integrated to deliver functionality critical for successful Health IT implementation in limited resource settings. It is anticipated that once fully implemented, the proposed m-health solution will facilitate superior monitoring and management of Tuberculosis and thereby reduce the alarming statistic regarding this disease in this region.