Interfragmentary compression and pull-out properties of 6.5-mm AO cancellous lag screws in a uniform synthetic material during tightening procedures. (April 2017)

• Record Type: Journal Article
• Authors: Sun, Peidong; Xu, Daqiang; Zhao, Weidong; Jiao, Peifeng; Li, Zeyu; Liu, Chang; Ouyang, Jun
• Is Part Of: Medical engineering & physics. Volume 42(2017)
• Page Start: 116
• Page End: 120
• Publication Date: 2017-04
• Subjects: AO cancellous lag screw -- Pull-out strength -- Interfragmentary compressive force -- Synthetic cancellous bone -- Tightening procedure; Biomedical engineering -- Periodicals; Biomedical Engineering -- Periodicals; Physics -- Periodicals; Génie biomédical -- Périodiques; Biomedical engineering; Electronic journals; Periodicals; 610.28
• DOI: 10.1016/j.medengphy.2017.01.011
• Languages: English
• ISSNs: 1350-4533

Abstract

Hightlights: The existence of the optimum balance between interfragmentary compressive force (IFCF) and pull-out strength (POS) was directly proved based on current test method during the AO screw tightening procedure. The tightening degrees (rotation angles) of 100–150° appear to offer the optimum balance during screw inserting procedure. The IFCF and POS values will not simultaneously achieve peak values. Therefore, the optimum balance of these parameters demonstrated herein necessitates a compromise. Abstract: AO lag screws are widely used in surgical intra-articular fracture treatment for anatomical reduction and rigid fixation. Interfragmentary compressive force (IFCF) and pull-out strength (POS) are two critical parameters generated by AO lag screws during tightening, and both of these parameters could be used to estimate screw insert conditions to prevent screw stripping. The aim of this study is to evaluate the IFCF and POS of AO cancellous screws inserted into uniform synthetic cancellous bone during tightening procedures. Seven synthetic cancellous bone blocks were used for this research. Each test contained two continuous portions as follows: the rotation test portion and the pull-out test portion. IFCF and POS were captured by the pressure transducer and the sensor of the test machine. The properties of IFCF and POS based on tightening degrees were obtained in this study. The ideal balance between POS and IFCF during screw tightening exists, and the peak values of these parameters cannot be simultaneously achieved. Moreover, rotation angles of 100–150° appear to serve as the optimum balance between IFCF and POS in the present study.