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Can barb thread design improve the pullout strength of bone screws?: a biomechanical study and finite element explanation

AIMS: To draw a comparison of the pullout strengths of buttress thread, barb thread, and reverse buttress thread bone screws. METHODS: Buttress thread, barb thread, and reverse buttress thread bone screws were inserted into synthetic cancellous bone blocks. Five screw-block constructs per group were...

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Detalles Bibliográficos
Autores principales: Feng, Xiaoreng, Qi, Weichen, Fang, Christian X., Lu, William W., Leung, Frankie K. L., Chen, Bin
Formato: Online Artículo Texto
Lenguaje:English
Publicado: The British Editorial Society of Bone & Joint Surgery 2021
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7937542/
https://www.ncbi.nlm.nih.gov/pubmed/33522293
http://dx.doi.org/10.1302/2046-3758.102.BJR-2020-0072.R2
Descripción
Sumario:AIMS: To draw a comparison of the pullout strengths of buttress thread, barb thread, and reverse buttress thread bone screws. METHODS: Buttress thread, barb thread, and reverse buttress thread bone screws were inserted into synthetic cancellous bone blocks. Five screw-block constructs per group were tested to failure in an axial pullout test. The pullout strengths were calculated and compared. A finite element analysis (FEA) was performed to explore the underlying failure mechanisms. FEA models of the three different screw-bone constructs were developed. A pullout force of 250 N was applied to the screw head with a fixed bone model. The compressive and tensile strain contours of the midsagittal plane of the three bone models were plotted and compared. RESULTS: The barb thread demonstrated the lowest pullout strength (mean 176.16 N (SD 3.10)) among the three thread types. It formed a considerably larger region with high tensile strains and a slightly smaller region with high compressive strains within the surrounding bone structure. The reverse buttress thread demonstrated the highest pullout strength (mean 254.69 N (SD 4.15)) among the three types of thread. It formed a considerably larger region with high compressive strains and a slightly smaller region with high tensile strains within the surrounding bone structure. CONCLUSION: Bone screws with a reverse buttress thread design will significantly increase the pullout strength. Cite this article: Bone Joint Res 2021;10(2):105–112.