Finite element analysis of a bone-implant system with the proximal femur nail.

Static analysis with finite element of a realistic femur nail bone-implant system in a typical proximal femoral fracture under physiological load bearing situations provides results for stress, displacement and strain. The question to be answered is, if simulation with the finite element analysis is able to explain biomechanically clinical observed patterns of failure. Surface-Reconstruction with CT database of a proximal femur and reconstruction with CT based density data was done. Next steps were to unite the bone structure with the Proximal Femoral Nail and to model two relevant fractures (31-A2.2 and A2.3 according AO). After modelling of geometry, isotropic material behaviour and load application numeric calculation of the femur-nail system with FE-software was performed. FE simulation mainly shows an axial dislocation of the femoral head screw with nearly no dislocation of the antirotation screw. This so-called z-effect therefore means: (1) Tilting of the proximal main fragment around the sagittal axis between the screws and (2) relative movement of both screws in the frontal plane. Relative movement of the two screws against each other could be the reason for implant failure, the so called cut out. Furthermore simulation shows different gliding of the screws explaining the so called z-telescoping. The analyzed stress patterns have to be relativized, because isotropic material behaviour of cancellous bone was assumed. Further examinations for this issue are necessary.     

A prospective, randomized study: day 3 versus hatching blastocyst stage

Hum. Reprod.,      

Endoscopic pterygopalatine space surgery

Although lesions of the pterygopalatine space are uncommon, there are instances in which this relatively inaccessible region must be entered for biopsy or excision of masses. Traditional open approaches to the pterygopalatine space, involving external or intraoral incisions, provide limited visualization and carry associated morbidities. The evolution and advancement of endoscopic sinus surgical technique in recent years has led to its application to anatomic areas outside the strict limits of the sinonasal cavities. Such minimally invasive approaches are safe, effective, and spare unnecessary discomfort to the patient. This article describes the authors' method for performing an endoscopic approach to the pterygopalatine space.     

Die infizierte Gelenkendoprothese

Trauma und Berufskrankheit - Als schwerste Komplikation der Gelenkendoprothetik bleibt die periprothetische Infektion eine Herausforderung—heutzutage nicht nur für den Chirurgen, sondern...     

Catecholaminergic polymorphic ventricular tachycardia in a child: an often unrecognized diagnosis]

Catecholaminergic polymorphic ventricular tachycardia is important to be diagnosed as an underlying disease in children with syncope and normal heart, because of its poor prognosis. CASE REPORT: A 3-year-old boy was referred for stress and emotion induced syncope. Primary ventricular arrhythmia, consisting of salvos of bidirectional ventricular tachycardia, was reproducibly induced by physical exertion. The syncopal events and severe arrhythmia disappeared with beta-blocking therapy. CONCLUSION: Despite its rare occurrence, catecholaminergic polymorphic ventricular tachycardia is an important cause of stress and emotion induced syncope and sudden death in children.