A biomechanical test study of screw fixation for scaphoid fractures
GUO Yang
TIAN Guang-lei
TIAN Wen
JIANG Bao-guo
HAN Na
Abstract：Objective To evaluate the effects of the middle and vertical positions of the screw on the ifxation stability in the treatment of oblique scaphoid fractures using biomechanical testing. Methods Oblique osteotomies for 32 sawbone scaphoids that were identical in the shape and texture were designed, and each specimen was ifxed with a screw. According to the positions of the screw and the fracture plane, sawbone scaphoids were divided into 4 groups. In group A, the screw was perpendicular to the fracture plane and was central in the scaphoid. In group B, the screw was not perpendicular to the fracture plane and was central in the scaphoid. In group C, the screw was perpendicular to the fracture plane and was eccentric in the scaphoid. In group D, the screw was neither perpendicular to the fracture plane nor central in the scaphoid. There were 8 cases in each group. The Computed Tomography ( CT ) scan was performed on 1 specimen, and the positions of the osteotomy plane and the screw guide pin were designed in biomechanical testing using the preoperative planning and the surgery simulation software. The specimen was placed under the increasing load of a pneumatically driven plunger to measure and compare the maximum load and displacement at fixation failure among the study groups. Results The average maximum load and displacement were ( 398.5 N, 2.8 mm ) in group A, ( 393.1 N, 2.9 mm ) in group B, ( 348.25 N, 3.6 mm ) in group C and ( 342.50 N, 3.8 mm ) in group D, and the differences both between group A and Group B, group C and group D were not statistically different ( P>0.5 ). It was illustrated that whether the screw was perpendicular to the fracture plane or not was irrelevant to the stability of the screw ifxation. The maximum load in group A and group B was greater than that in group C and group D, and the differences between them was statistically different ( P<0.001 ). The maximum displacement in group A and group B was smaller than that in group C and group D, and the differences between them was statistically different ( P<0.001 ). Conclusions In this biomechanical test study of unstable oblique scaphoid fractures, it is shown that higher stability of ifxation can be achieved with the screw placed centrally in the scaphoid, and the stability has nothing to do with whether the screw is perpendicular to the fracture plane or not.
Keywords：BiomechanicsInternal ifxationScaphoid fractureWrist
Publication Date：2014-01-01
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：5( 301-305 )