Study On Biomechanical Stability Of Different Internal Fixation Methods For Acetabular Anterior Wall Fracture

Objectives To compare the biomechanical stability of four different internal fixation methods for acetabular anterior wall fracture,explore the ideal method of internal fixation for the fracture of anterior acetabular wall,and provide biomechanical basis for the clinical treatment of acetabular anterior wall fracture.Methods A total of 20 preserved adult semipelvic specimens were selected to establish the acetabular anterior wall fracture model.The fracture models were randomly divided into group A,group B,group C and group D,with five fracture models in each group.After full anatomical reduction of the fracture with a femoral head as template under direct vision,the group A was fixed with a reconstruction plate along the upper margin of the pelvis,the group B was fixed with a reconstruction plate along the inner margin of the pelvis,the group C was fixed with an antegrade lag screw,and the group D was fixed with a retrograde lag screw.Axial loading compression test was carried out for each group on the inverted single foot standing position.Before the experiment,three times loading with 150 N were preloaded to eliminate the creep of the specimens.Then the load was stressed continuously with the load increasing continuously,and the loading speed was 10N/s.The horizontal displacement of the acetabular anterior wall fracture was measured at 400 N,800N,1200 N,1600N and 2000 N load,and the shear rigidity was calculated.The biomechanical stability of the four groups were compared.Results Under the same load,the horizontal displacement of the fracture end: group A >group B >group C>group D,the shear rigidity of internal fixation: group D >group C >group B>group A.There was no significant difference between the 4 groups in the horizontal displacement and the shear rigidity of internal fixation when the load was 400N(P>0.05).When the load was 800 N to 2000 N,there was no significant difference between group C and group D in the horizontal displacement and the shear rigidity of internal fixation(P>0.05),but there was significant difference between the other groups(P<0.05).Conclusions In the four different internal fixation methods for the fracture of anterior acetabular wall,the stability of lag screw fixation was higher than that of reconstruction plate fixation,and the stability of antegrade lag screw fixation was similar to that of retrograde lag screw fixation.