1,720,967 research outputs found
Stress pattern in a prosthetic stem: FEcomparison between the standardised experimental fatigue test (ISO 7206) and actualstresses on an implanted stem
No full textModel validation and FE analysis of the head bonnet impact
No full textThe directive 2003/102/CE intends to reduce the injuries of the pedestrians during frontal impact with passenger cars. The directive describes the device that must be employed to simulate pedestrian head: HIC is used to evaluate the severity of the impact. This work has two goals: to realize a FE model of pedestrian headform impactor; to optimize the car bonnet structure in order to reduce the accelerations and consequently the HIC (Head Injury Criteria) [Schmitt,2007
The variability of prosthesis positioning and the resulting geometry of coxo-femoral joint
No full textThis work is focused on femoral prosthesis positioning inside bone and its consequences on stress distribution. Five synthetic femurs were employed: one femur was left unimplanted (NF), four femurs were implanted with two different prostheses (PF, A or B models); all implants were performed with specific instruments, by orthopaedic surgeons who usually perform that surgery. The CAD models of all femura were obtained from CT scans; a reference system was defined in NF in order to compare joint geometry between NF and PE The following parameters were considered: femur height, head offset, angle between femur axis and prosthesis shaft axis, angle between neck axis and femur axis. Each one has functional consequences: impaired art length produces discomfort and unbalanced muscle forces, a wrong offset determines a congruent variation in stress moduli; prosthesis orientation substantially modifies stress pattern inside bone. The differences between joint geometry in NF and PF and between two femurs implanted with the same prosthesis have been found to be significant. For example, depending on prosthesis models, an augmented height (up to 3.4mm) or a reduced height (up to 22.0mm) were observed, with respect to NF. Head offset differed of about 3.0mm between NF and PF; the angle between prosthesis shaft axis and femur axis reached about 4.30 (model A), or 7.00 (model B). These results suggest that orthopaedic implant design cannot be performed in a deterministic manner only, but also the variability due to manual and sensorial abilities of surgeons must be taken into account
Metodi numerici e sperimentali per la valutazione pre-clinica di ricostruzioni complesse
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Analisi parametrica per via numerica e sperimentale delle viti ortopediche in relazione alla qualita’ dell’osso
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Multibody model of hip dislocation
No full textHip dislocation is still a relevant clinical issue of hip arthroplasty [Stralen et al. 2003, Berry et al. 2004]. The factors which play an influence on the propensity for dislocation are related to the patient's anamnesis and to the surgical interview: for example, the acetabular position and orientation, the femoral head size, the neck diameter and length, etc. An optimal set up of these variables can be accomplished through a careful design of both the prosthetic components and the surgical interview. This work demonstrates that a multibody model of the joint can be a useful aid as a design tool: it can allow to verify the amplitude of the allowed movements for each given configuratio
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