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Experimental and Numerical Evaluation of the Pullout Strength of Self-tapping Bone Screws in Normal and Osteoporotic Bone

Battula, Suneel Ranga Sai
http://rave.ohiolink.edu/etdc/view?acc_num=akron1194988102

Abstract Details

2007, Doctor of Philosophy, University of Akron, Biomedical Engineering.
Self-tapping cortical screws (STS) are being increasingly used for fracture fixation in metaphyseal region due to their advantage over the other bone screws. The objective of this study was to compare the pullout index and loading energy of the STS inserted in normal and osteoporotic bone blocks. A 3D model of the bone-screw interface was developed to numerically evaluate the effect of bone quality on pullout strength. Previous studies indicated the significance of pilot hole, insertion torque, screw size and cutting flutes in normal bone. This study evaluated their effects in osteoporotic bone model and compared them experimentally and numerically. For the pullout study the screws were divided into five groups each representing a depth of insertion in normal and osteoporotic bones (six screws per group), respectively. The effects of pilot hole size, cutting flutes, manufacturer, material and screw size on the pullout index (PI) were also evaluated in this study by categorizing the screws into different groups (six screws per group). The pullout protocol specified by ASTM F.543-02 standard for metallic screws was experimentally implemented on a sample size determined by power analysis. Synthetic bone models were used for experimental evaluation. ANOVA was used to statistically analyze the effect of screw size and cutting flutes on the pullout strength. Experimental values indicated that the PI of screws inserted into normal bone blocks was significantly different (p< 0.05) from that of osteoporotic bone blocks. The results also demonstrated that the PI of the screws increased with the depth of insertion in both normal and osteoporotic bones. The performance of stainless steel screws was observed to be significantly different from that of titanium screws in osteoporotic bone but not in normal bone blocks. It was also observed that there was no significant difference in PI and loading energy (LE) for screws from different manufacturers in normal and osteoporotic bone. A finite element model, with non-linear material properties, was analyzed to investigate the interaction of the bone quality and depth of insertion on the pullout characteristics. Bone quality was observed to have a significant effect on the PI as in the experimental testing. The model was validated with the experimental data for the effect of depth of insertion on the PI for normal and osteoporotic bones.
Glen Njus (Advisor)
191 p.
Engineering, Biomedical
Pullout Strength; Osteoporosis; Bone Screws; Finite Element Model;

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Citations

  • Battula, S. R. S. (2007). Experimental and Numerical Evaluation of the Pullout Strength of Self-tapping Bone Screws in Normal and Osteoporotic Bone [Doctoral dissertation, University of Akron]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=akron1194988102

    APA Style (7th edition)

  • Battula, Suneel Ranga Sai. Experimental and Numerical Evaluation of the Pullout Strength of Self-tapping Bone Screws in Normal and Osteoporotic Bone. 2007. University of Akron, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=akron1194988102.

    MLA Style (8th edition)

  • Battula, Suneel Ranga Sai. "Experimental and Numerical Evaluation of the Pullout Strength of Self-tapping Bone Screws in Normal and Osteoporotic Bone." Doctoral dissertation, University of Akron, 2007. http://rave.ohiolink.edu/etdc/view?acc_num=akron1194988102

    Chicago Manual of Style (17th edition)

akron1194988102
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© 2007, all rights reserved.
This open access ETD is published by University of Akron and OhioLINK.