Biomechanical Study On Diferent Fixation Of Acetabular Fractures In Quadrilateral Surface

Objectives To compare the biomechanical difference of 4 kinds of internal fixations for acetabular fracture in quadrilateral area.Methods The quadrilateral area fracture models were created by 16 adult males hemipelves specimens, and were randomly divided into 4 groups according to different internal fixation methods(n=4), infrapectineal buttress reconstruction plate(group A), infrapectineal buttress locking reconstruction plate(group B), reconstruction plate combined with trans-plate quadrilateral screws(group C), and anterior reconstruction plate-lag screw(group D). Then the willow leaf films were stuck on the femoral head and vertical compressing loading was continued via the fracture models, followed by measurement of physiological weight 600 N intact acetabulum in group I(No fracture line was made) and internal fixation of acetabular dome contact characteristics and horizontal and vertical displacements in A, B, C and D groups.Results Under physiological weight 600 N, acetabular dome contact characteristics in four groups failed to return to normal, there was a significant difference on the loading area, the mean pressure, the peak pressure among groups(P<0.05). Under the same loading, the horizontal and longitudinal displacements of groups A, B, C, and D were decreased gradually; when the loading reached 1800 N, the longitudinal displacement of group A was more than 3.00 mm, indicating the failure criterion, while the axial stiffness increased gradually. Under 200 N loading, there was no significant difference(P>0.05) in horizontal displacement, longitudinal displacement, and axial stiffness among 4 groups. When the loading reached 600~1800 N, significant difference was found in horizontal displacement, longitudinal displacement, and axial stiffness(P<0.05) except the horizontal displacement between groups C and D(P>0.05).Conclusions For the acetabular quadrilateral area fracture, anterior reconstruction platelag screw for internal fixation has highest stability and the acetabular dome contact characteristics is the best, followed by reconstruction plate combined with trans-plate quadrilateral screws, and they are better than infrapectineal buttress reconstruction plate and infrapectineal buttress locking compression plate.