Bewertung der stabilität von frakturfixationssystemen: mechanische vorrichtung zur untersuchung der 3-D-steifigkeit in vitro.

Kassi, J.P., Hoffmann, J.E., Heller, M., Raschke, M. and Duda, G.N. (2001) Bewertung der stabilität von frakturfixationssystemen: mechanische vorrichtung zur untersuchung der 3-D-steifigkeit in vitro. Biomedical Engineering / Biomedizinische Technik, 46 (9), 247-252. (doi:10.1515/bmte.2001.46.9.247). (PMID:11593982)

Abstract

Different fixation systems are used for fracture and defect treatment. A prerequisite for complication free healing is sufficient mechanical stability of the osteosynthesis. In vitro investigations offer the possibility of both analysing and assessing the pre-clinical fixation stability. Due to the complex loading environment in vivo, stiffness analysis should include a complete determination of the stiffness under standardised conditions. Based on a mathematical procedure to calculate the 3-D stiffness, a mechanical testing device for the 3-D loading of fixation systems was designed and integrated in the existing test set-up. The set-up consisted of a material testing machine to produce the necessary loads and an optical measurement device to detect the resulting inter-fragmentary movements. To validate the testing device, the 3-D stiffness matrices of different Ilizarov fixator configurations were determined and compared. The good reproducibility of the test was reflected in the small intra-individual variability of the stiffness components. A distinct direction dependence of the fixator stiffness was observed. Increasing the number of rings led to a stiffness increase of up to 50%, especially in bending. The presented testing device allows a complete standardised determination of the stiffness of different fixation systems. It considers the direction dependence of the stiffness and creates a prerequisite for a more direct implant comparison.

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Contributors

Author: M. Heller

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