Einfluss unterschiedlicher Konservierungsmethoden auf die mechanischen Eigenschaften von porcinen Metatarsalia in polyzyklischen Belastungen
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Abstract
Influence of different preservation methods on the mechanical properties of porcine metatarsals in polycyclic loads
Introduction: To establish new osteosynthesis materials or techniques, mechanical test procedures on in-vitro specimens are the current standard. In addition to load-to-failure tests, polycyclic submaximal loads are used as an approximation to physiological conditions. The availability of fresh or frozen human bone samples is limited, so chemically fixed samples could facilitate the procurement of sample material. However, it is not yet sufficiently understood whether the treatment of the bone substance with chemicals changes its mechanical properties. Porcine bones were used to investigate this influence, as they are similar to human bones in terms of structure and mechanical properties and are easily available in fresh condition.
The aim of the work was to investigate the influence of different preservation methods on the mechanical stability of osteosyntheses under cyclic load.
Methods: Porcine metatarsals III and IV were measured and randomised into seven different treatment groups (n ≥ 19):
G1: fresh specimens (control group)
G2: deep freezing at -18°C
G3: deep freezing at -18°C with repeated thawing cycles G4: formalin solution
G5: glycerol solution
G6: Thiel ́s fixation
G7: vacuumisation and storage at 6°C
Before and after preservation, the bone mineral density (BMD) of each sample was determined using Duel X-ray absorptiometry (DXA). A modified three-point bending test analogue to Ochman et al., 2011 was performed for fracture generation. Common mechanical parameters were measured. After conventional plate osteosynthesis of the resulting fracture with a five-hole stainless steel plate and four 2.7 mm bicortically inserted stainless steel screws, each bone was loaded for 10,000 cycles with submaximal load. Finally, a new load was applied until failure to test the resulting stability of the osteosynthesis. The statistical analysis was performed with IBM SPSS Statistics at a significance level of α = 0.05.
Results: The seven groups were smiliar concerning anatomical measurements. Only G4 showed a significantly lower BMD than G1 even before preservation (p = .048). After preservation, however, there was a significant difference to G1 in G3 (p = .027) uniquely. In cyclic loading, there was no significant difference between the groups in terms of loosening and number of cycles sustained. Only, the amount of failures during cyclic loading was away higher in G4 and G7. The final stability test until failure showed significantly lower values for the samples from G4 for the displacement at failure (p < .001), the displacement at maximum load (p < .025) and the yield point (p < .030). In G5 (p < .001) and G6 (p = .013), the displacement at failure was also altered, which is unterstood as a sign of lower plastic absorbation capacity.
Conclusion: While the physical preservation methods do not or almost not influence the stability of the metatarsals under cyclic loading, chemical preservation leads to significant changes in the mechanical properties of the osteosynthetically treated bone substance. Therefore, the transferability of biomechanical studies with chemically preserved samples to fresh bone is limited.
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Issued: 0026-04-14
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FB20:Medizin
Language
de
Keywords
biochemischzyklische BelastungKonservierungsmethodenmetatarsalia
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Kühlein-Lehr, Moritz: Einfluss unterschiedlicher Konservierungsmethoden auf die mechanischen Eigenschaften von porcinen Metatarsalia in polyzyklischen Belastungen. : 0026-04-14. DOI: https://doi.org/10.17192/openumr/671.
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