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Civil-Comp Proceedings
ISSN 1759-3433
CCP: 84
Edited by: B.H.V. Topping, G. Montero and R. Montenegro
Paper 189

Numerical Modelling of the Mechanical Behaviour of a PHILOS Plate and a PHN Nail in the Treatment of a Proximal Humeral Fracture

C. Pereira1, F.V. Antunes2, M.C. Gaspar3, A. Mateus4, A. Foruria de Diego5 and M.T. Carrascal Morillo6

1Department of Mechanical Engineering, Coimbra Polytechnic Institute, Portugal
2Department of Mechanical Engineering, Coimbra University, Portugal
3Department of Industrial Engineering, Castelo Branco Polytechnic Institute, Portugal
4Department of Mechanical Engineering, Leiria Polytechnic Institute, Portugal
5La Paz University Hospital, Spain
6Department of Mechanical Engineering, Technical Superior School of Industrial Engineers, Spain

Full Bibliographic Reference for this paper
C. Pereira, F.V. Antunes, M.C. Gaspar, A. Mateus, A. Foruria de Diego, M.T. Carrascal Morillo, "Numerical Modelling of the Mechanical Behaviour of a PHILOS Plate and a PHN Nail in the Treatment of a Proximal Humeral Fracture", in B.H.V. Topping, G. Montero, R. Montenegro, (Editors), "Proceedings of the Fifth International Conference on Engineering Computational Technology", Civil-Comp Press, Stirlingshire, UK, Paper 189, 2006. doi:10.4203/ccp.84.189
Keywords: biomechanical models, finite element method, humeral fracture, orthopaedic, osteosynthesis, reverse engineering.

The purpose of this study was to develop finite element models to analyze the biomechanical behaviour of two types of internal fixation: i) a precontoured plate with locking screws and ii) an intramedullary nail with a fixed-angle spiral blade as osteosynthesis material in the treatment of a proximal humeral fracture.

Unfortunately, the biomechanical characteristics of these fixed-angle locking devices are not very well known. Assessing their biomechanical properties, developing and improving their design, and thus their performance in the internal fixation of proximal humerus fractures, are major challenges.

Accurate biomechanical models can be used to predict the mechanical failure of orthopaedic implants [1], for their pre-clinical testing [2], and in the diagnosis of many complex pathologies [3,4,5]. Studies of bone remodelling [6], or simply its ageing [7], can also make use of these models. In addition, three-dimensional visualisation has been playing a major role in the pre-surgery planning and preparation of operations, in terms of which type of surgical techniques should be used [8,9].

This study thus set out to develop finite element models to analyze the biomechanical behaviour of PHILOS titanium plates and PHN intramedullary titanium nails as osteosynthesis material in the treatment of a proximal humerus fracture. To validate the numerical results, an experimental setup was first developed, where six pairs of embalmed cadaveric humerus were submitted to a set of torsional loads up to fracture.

Based on experimental results it can be concluded that PHILOS plates provide some biomechanical advantages over PHN intramedullary nails, such as higher torsional load capacity, greater angular displacement and a higher energy absorption capacity, and so greater plastic deformation capacity, before failure. These characteristics are crucial, particularly if the bones present osteoporotic problems [10]. Maximum stresses obtained with the finite element method at experimental failure torques were relatively low compared with the bone's failure stress. The mismatch can be explained by the occurrence of failure mechanisms, i.e. fracture, which are not being modelled numerically. However, the numerical simulation also reveals the superiority of biomechanical behaviour exhibited by the PHILOS plate relative to PHN nail.

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