Biomechanical test to determination the diameter of the polymethylmethacrylate bar in external skeletal fixator type Ia in swine humerusi

B. Schmitt G.M.C. Serafini R.N. Libardoni F.W. Souza J.P.S. Feranti C.R. Cauduro A.S. Amaral M.V. Brun About the authors

ABSTRACT

Bone fractures can be corrected from external skeletal fixators (ESF) in a fairly common internal stabilization method, in which connector bars polymethylmethacrylate (PMMA) is used. PMMA is used without criterion of diameter, and it can break if it is too thin or too heavy. It can be uncomfortable when bulky. The aim of this study was to test, through biomechanical axial compression and bending which is the ideal connector bar diameter PMMA, correlated to bone diameter for use in type Ia ESF. Twenty-four humerus were used to make measurements of length, diameter, circumference, and biomechanical testing. After the bars confected with 1.5 times the average diameter of the bone (group I), the same diameter (group II) and 0.5 times the diameter of the bone (group III). With the obtained results, using GII and GIII results, it was observed that the connector bars in group II were more resistant than the bones in the compression test. In the bending test, the bones resisted flexion strength when compared to group III and the group II was 4.3 times more resistant than group III in the same mechanical test. The results allow a direction for making bars considering bone diameter as a reference.

Keywords:
swine acrylic resin; resistance; axial compression; bending

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