The Role of Pedicle Screw Surface on Insertion Torque and Pullout Strength^[∗]

Abstract

Objective Compare by mechanical tests the pullout resistance and the insertion torque of rough and smooth pedicle screws.

Methods Pedicle screws with rough surface and smooth surface, with diameters of 4.8; 5.5 and 6.5 mm, were inserted in polyurethane blocks with density of 10 PCF (0.16 g/cm3). Insertion torque and pullout strength were assessed.

Results The pullout strength of the rough surface and smooth surface screws did not differ, except in the group of 4.8 mm diameter screws. In this group, the rough surface screws showed greater resistance to pullout.

Conclusion Pedicle screws with a rough surface did not show increased pullout resistance in the acute phase of their insertion in polyurethane blocks compared to smooth surface screws. The rough surface screws had a higher insertion torque than the smooth surface screws, depending on the diameter of the screw and the preparation of the pilot hole.

Keywords

spine - bone screws - biomechanical phenomena

Authors' Declaration of Contribution

Each author contributed individually and significantly to the development of this article. Fleury R. B. C. (0000–0001–7643–6466) *: Substantial contributions to the conception and design of the work, acquisition and interpretation of data for the work and final approval of the version to be published; Shimano A. C.(0000–0002–3119–2362) *: contribution to data collection, analysis and final approval; Matos T. D. (0000–0003–3853–502X) *: contribution to data collection and analysis; Teixeira K. O. (0000–0002–8165–2427) *: contribution to data collection and analysis; Romero V (0000–0002–3278–5223) *: review for important intellectual content; Defino H. L. A. (0000–0003–4274–0130) *: Substantial contributions to the conception and design of the work, contributions to the analysis and interpretation of data for the work and final approval of the version to be published.

^∗ Work developed in the Department of Biomechanics, Medicine and Rehabilitation of the Locomotor System, Ribeirão Preto Medical School, Universidade de São Paulo, Ribeirão Preto, SP, Brazil.

Publikationsverlauf

Eingereicht: 31. August 2019

Angenommen: 20. Februar 2020

Artikel online veröffentlicht:
08. Juni 2020

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