| OBJECTIVE: To explore the biomechanical difference between cortical allograft struts fixed by different methods and the influent strength by the screw-holes. METHOD:48cortical allograft struts(50×10×3mm) were divided into three groups: group A, group B and group C. In group A ,two 3.5mm diameter holes with were drilled through the struts while in group C only one and, in group B, none hole drilled in the struts. Biomechanical tests were performed. Parameters studied included maximum strength of bending, compression, extraction and torque. 27 cadaveric femurs were taken from fourteen specimens of children and made into a fracture model by sawing them in the mid-shaft with a angle of 45-degree to the long axis of the bone. These models were assigned randomly to three groups: group D, group E, group F. Fourty-five cortical freeze-dried allografts (110×10×3mm) were harvest. In group D, the fractures were fixed with two cortical onlay struts(take from 45 struts randomly) on the lateral and medial sides, and tightened by PDS suturs. In group E, fractures were fixed with bone screws and two struts on the lateral and medial sides. In group F, the fracture was fixed only one strut and bone screws, biomechanical test of three bending test on 50N,100N, 150N load, torque on 5°, 10°, 15° and compression on 100N,200N and 300Nwere performed, and then test maximum strength.RESULT: In group A, the maximum bending, maximum torque, maximum compression and extraction was an average of 57.63±8.14Mpa,1.68±0.19N.m, 115.25±31.99MPa and 72.00±22MPa; In group B,98.25±28MPa, 2.90±0.45N.m,172.01±22.39MPa and 117.50±25.00 MPa, respectively. In group C, 134. 67±28. 35 MPa, 84. 00 ± 20. 31 MPa, 61. 64± 10.44 MPa, 1. 91 ± 0. 23N. m Struts in group A and C were weaker than those in group B(P<0.05). More changed on the maximum torque than other parameters.At every classified load on the three bending tests,displacement of group D was...
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