Interfragmentary compression and pull-out properties of 6.5-mm AO cancellous lag screws in a uniform synthetic material during tightening procedures.
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.
Guangdong Provincial Key Laboratory of Medical Biomechanics, Department of Anatomy, Southern Medical University, #1023 Shatai Road, Baiyun District, Guangzhou, PR China.
Peidong
P
Sun
The People's Hospital of Jianhu County, Jiangsu, PR China.
Daqiang
D
Xu
Guangdong Provincial Key Laboratory of Medical Biomechanics, Department of Anatomy, Southern Medical University, #1023 Shatai Road, Baiyun District, Guangzhou, PR China.
Weidong
W
Zhao
Guangdong Provincial Key Laboratory of Medical Biomechanics, Department of Anatomy, Southern Medical University, #1023 Shatai Road, Baiyun District, Guangzhou, PR China.
Peifeng
P
Jiao
Guangdong Provincial Key Laboratory of Medical Biomechanics, Department of Anatomy, Southern Medical University, #1023 Shatai Road, Baiyun District, Guangzhou, PR China.
Zeyu
Z
Li
Guangdong Provincial Key Laboratory of Medical Biomechanics, Department of Anatomy, Southern Medical University, #1023 Shatai Road, Baiyun District, Guangzhou, PR China.
Chang
C
Liu
Guangdong Provincial Key Laboratory of Medical Biomechanics, Department of Anatomy, Southern Medical University, #1023 Shatai Road, Baiyun District, Guangzhou, PR China. Electronic address: jouyang@126.com.
Jun
J
Ouyang
D001863:Bone Screws; D000071556:Cancellous Bone; D019245:Compressive Strength; D004867:Equipment Design; D008422:Materials Testing / Q000295:instrumentation*
AO cancellous lag screw; Interfragmentary compressive force; Pull-out strength; Synthetic cancellous bone; Tightening procedure