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Biomechanical Evaluation of Novel Expanding Pedicle Screws Suitable for Osteoporotic Lumbar Spine

Asadollahi, Mohammad Saeid
http://rave.ohiolink.edu/etdc/view?acc_num=toledo1449711700

Abstract Details

2015, Master of Science, University of Toledo, Bioengineering.
Pedicle screw fixation is the most common treatment method for correction of spine disorders such as deformity, disc degeneration, and trauma. However, traditional screw designs suffer from inadequate fixation in patients with osteoporosis. The objective of this study was to develop several novel expanding screw concepts to address the loosening of screws in osteoporotic bone. To achieve this goal, four new expanding designs, each offering different features, are proposed. Three are reversible and collapsible in case the need arises to remove the screws. FE simulations were carried out for all screw designs and for traditional screws. Based on the FE results, the two best screw designs were prototyped for axial pullout in lumbar vertebrae. FE results showed improved pullout force for all the designs. In an osteoporotic bone, the failure load dropped to 170 N (38 percent decrease) for the conventional screw, while it was restored by the new designs. For the cancellous expanding screw, the failure load was 360 N, which is almost twice the value for a conventional screw in osteoporotic bone and 33 percent greater than for a conventional screw in normal bone. Screws providing anchorage in the cortical shell yielded significantly better results. Window expanding screws showed the largest pullout force (840 N, an increase of 196 percent) compared to a conventional screw in normal bone. Cortical and transverse expanding screws also performed better, increasing the failure load to 660 and 540 N, respectively. Cadaver study of the two transverse and bottom expanding screw showed similar pull-out strength to the conventional screw.
Vijay Goel (Advisor)
Anand Agarwal (Committee Member)
Edward Nyman (Committee Member)
118 p.
Biomedical Engineering

Recommended Citations

Citations

  • Asadollahi, M. S. (2015). Biomechanical Evaluation of Novel Expanding Pedicle Screws Suitable for Osteoporotic Lumbar Spine [Master's thesis, University of Toledo]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1449711700

    APA Style (7th edition)

  • Asadollahi, Mohammad. Biomechanical Evaluation of Novel Expanding Pedicle Screws Suitable for Osteoporotic Lumbar Spine. 2015. University of Toledo, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=toledo1449711700.

    MLA Style (8th edition)

  • Asadollahi, Mohammad. "Biomechanical Evaluation of Novel Expanding Pedicle Screws Suitable for Osteoporotic Lumbar Spine." Master's thesis, University of Toledo, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1449711700

    Chicago Manual of Style (17th edition)

toledo1449711700
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© 2015, all rights reserved.
This open access ETD is published by University of Toledo and OhioLINK.