Increasing stability by pre-bending the nails in elastic stable intramedullary nailing: a biomechanical analysis of a synthetic femoral spiral fracture model

Elastic stable intramedullary nailing (ESIN) is generally acknowledged to be the treatment of choice for displaced diaphyseal femoral fractures in children over the age of three years, although complication rates of up to 50% are described. Pre-bending the nails is recommended, but there are no published data to support this. Using synthetic bones and a standardised simulated fracture, we performed biomechanical testing to determine the influence on the stability of the fracture of pre-bending the nails before implantation. Standard ESIN was performed on 24 synthetic femoral models with a spiral fracture. In eight?cases the nails were inserted without any pre-bending, in a further eight cases they were pre-bent to 30° and in the last group of eight cases they were pre-bent to 60°. Mechanical testing revealed that pre-bending to 60° produced a significant increase in the stiffness or stability of the fracture. Pre-bending to 60° showed a significant positive influence on the stiffness compared with unbent nails. Pre-bending to 30° improved stiffness only slightly. These findings validate the recommendations for pre-bending, but the degree of pre-bend should exceed 30°. Adopting higher degrees of pre-bending should improve stability in spiral fractures and reduce the complications of varus deformity and shortening.     

Skin burns after laser exposure: histological analysis and predictive simulation

Thermal effects of laser irradiation on skin are investigated in this paper. The main purpose is to determine the damage level induced by a laser exposure. Potential burns induced by two lasers (wavelength 808nm and 1940nm) are studied and animal experimentations are performed. Several exposure durations and laser powers are tested. Based on previous works, a mathematical model dedicated to temperature prediction is proposed and finite-element method is implemented. This numerical predictive tool based on the bioheat equation takes into account heat losses due to the convection on skin surface, blood circulatory and also evaporation. Thermal behavior of each skin layer is also described considering distinct thermal and optical properties. Since the mathematical model is able to estimate damage levels, histological analyses were also carried through. It is confirmed that the mathematical model is an efficient predictive tool for estimation of damage caused by lasers and that thermal effects sharply depend on laser wavelength.     

Biomechanical analyses of the performance of Paralympians: from foundation to elite level

A biomechanical analysis of sports performance provides an objective method of determining performance of a particular sporting technique. In particular, it aims to add to the understanding of the mechanisms influencing performance, characterization of athletes and provide insights into injury predisposition. While the performance in sport of able-bodied athletes is well recognized in the literature, less information and understanding are known on the complexity, constraints and demands placed on the body of an individual with a disability. This article provides a dialogue that outlines scientific issues of the performance analysis of multi-level athletes with a disability, including Paralympians. Four integrated themes are explored, the first of which focuses on how biomechanics can contribute to the understanding of sports performance in athletes with a disability and how it may be used as an evidence-based tool. This latter point questions the potential for a possible cultural shift led by the emergence of user-friendly instruments. The second theme briefly discusses the role of reliability of sports performance and addresses the debate of two-dimensional and three-dimensional analyses. The third theme addresses key biomechanical parameters and provides guidance to clinicians and coaches on the approaches adopted using the biomechanical/sports performance analysis for an athlete with a disability starting out, to the emerging and elite Paralympian. For completeness of this discourse, the final theme is based on the controversial issues on the role of assisted devices, and the inclusion of Paralympians into able-bodied sport. All combined, this dialogue highlights the intricate relationship between biomechanics and training of individuals with a disability. Furthermore, it illustrates the complexity of modern training of athletes, which can only lead to a better appreciation of the performances to be delivered in the London 2012 Paralympic Games. Clinical relevance Biomechanical analysis can play a fundamental role in optimizing the performance of an athlete with a disability. Clinicians should be aware and understand the mechanisms that may influence performance and have an appreciation of the factors that may predispose such athletes to injury.     

Giant aneurysm of the main hepatic artery secondary to hereditary hemorrhagic telangiectasia: 3D contrast-enhanced MR angiography features

This case report describes a patient with Hereditary Hemorrhagic Telangiectasia and a giant hepatic artery aneurysm. Aneurysms of the hepatic artery are the second most common form of visceral artery aneurysms. The causes of hepatic artery aneurysms are atherosclerosis in 30% of cases, arteritides, periarterial inflammation, liver transplantation, and hepatic tumor embolization. To our knowledge no giant hepatic artery aneurysm has been described in relation to Weber-Rendu-Osler disease in the literature. These aneurysms probably develop because of hepatic arterio-venous fistulas and secondary to changes in arterial hemodynamics. The increased use of non invasive imaging techniques such as MRI before liver transplantation in patients with hereditary hemorrhagic telangiectasia reveals these asymptomatic aneurysms and makes it possible to choose the best therapeutic approach.