Anatomic Measurement And Correlation Of Themidpoint Of The Acetabular Notch And Acetabular Center

Objective: Measure the distance between the midpoint of acetabular notch and the center of acetabulum to investigate the correlation between the distance from acetabular notch center to acetabular center and the sum of vertical diameter and horizontal diameter of the acetabular opening plane.In order to find a new method to determine the center of the acetabulum in THA,and to provide anatomical basis for accurate placement of the acetabular prosthesis.Methods: 1.Select 20 normal adult dry pelvic specimens(40 hips),reveal a margin of acetabulum,anterior and posterior notch and Harris fossa.2.Firstly,to find the maximum vertical diameter in the upper and lower direction of the opening plane of the acetabulum,and then determine the horizontal diameter of the acetabular rim respectively,The maximum vertical diameter and the horizontal diameter are respectively two longitudinal bisector and two transverse bisector.The intersection point of longitudinal bisector and transverse bisector on the acetabular surface is the acetabular center O1.Secondly,determine the midpoint of the acetabular notch(A),and then measure the maximum vertical diameter of the acetabular rim,the horizontal diameter of the acetabular rim,the distance between the midpoint of acetabular notch and the center of acetabulum(AO1).Finally use the acetabular center locator(ACL)to measure the distance between the midpoint of line connected with acetabular notehes and the acetabular center MAC.3.Scatter plots of MAC and the sum of vertical diameter and horizontal diameter of the acetabular opening plane and scatter plots of the distance between the midpoint of acetabular notch and the center of acetabulum and the sum of vertical diameter and horizontal diameter of the acetabular opening plane are drawn.The experimental data measured were nanalyzed by using statistical software respectively.the correlation between the midpoint of acetabular notch and the center of acetabulum(AO1),MAC and the sum of vertical diameter and horizontal diameter of the acetabular opening plane.And the correlation coefficient between the two groups were compared.Results: Scatter diagrams are observed between the data change trend.The results indicate that it has a certain positive linear correlation between the sum of vertical diameter and horizontal diameter of the acetabular opening plane and the distance between the midpoint of acetabular notch and the center of acetabulum,MAC.The further use of SPSS software were calculated with the Pearson coefficient R=0.615,0.592.The ratio of the distance between the acetabular center and the midpoint of acetabular notch and the sum of vertical diameter and horizontal diameter of the acetabular opening plane is about 0.27.Conclusion:Pearson linear correlation coefficient showed that between the distance from the midpoint of acetabular notch to the center of acetabulum(AO1)and the sum of vertical diameter and horizontal diameter of the acetabular opening plane have a significant linear positive correlation.So we can obtain the values between the acetabular notch of the point and the center of acetabulum by measuring the sum of vertical diameter and horizontal diameter of the acetabular opening plane which provides a new method to determine quickly and accurately the center of the acetabulum and accurate placement of the acetabular cup.