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Does the Location of the Cutting Flute of Self-Tapping Screws in Bony Substrate Affect the Removal Torque?

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ABSTRACT
Introduction: An observation was made that when removing self-tapping cortical screws from patients bones, stripping or shearing of the head of the screw occurred more often in screws whose cutting flutes sat in cortical bone compared with screws that had penetrated the distal cortex with flutes exposed. Method: A model was designed to simulate screws with their cutting flutes either in contact with cortical bone or deep to cortical bone. Screws were grouped depending on the location of their cutting flutes and removal torque was measured. Results: Eighteen screws were included in final analysis. There was a statistically significant difference in average initial removal torque and average maximal removal torque with screws with their cutting flutes in substrate requiring significantly more torque to remove. Conclusion: We conclude that self-tapping cortical screws whose cutting flutes sit in cortical substrate require more torque to remove and are therefore more likely to fail. This finding may be used as a guide in pre-operative planning for removal of metalwork from patients.
 
Cite this paper
Graham, D. , Spiers, A. , Swarts, E. and Whitewood, C. (2015) Does the Location of the Cutting Flute of Self-Tapping Screws in Bony Substrate Affect the Removal Torque?. Open Journal of Orthopedics, 5, 1-5. doi: 10.4236/ojo.2015.51001.
 
References
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[4]Busam, M.L., Esther, R.J. and Obremskey, W.T. (2006) Hardware Removal: Indications and Expectations. Journal of the American Academy of Orthopaedic Surgeons, 14, 113-120.
 
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[7]Webb, J.A., Almaiyah, M., McVie, J. and Montgomery, R.J. (2008) Proximal Femoral Osteotomies in Children Using the Richards Hip Screw: Techniques, Outcome and Subsequent Removal. Journal of Children’s Orthopaedics, 2, 417-423.
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http://dx.doi.org/10.1016/0021-9290(93)90042-D                                                              eww150114lx
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