Anatomical And Imaging Study Of Safe Screw Placement Method In Posterior And Upper Internal Fixation Of Femoral Neck Fracture

Objective:Through the study of anatomical morphology and imaging of a large number of adult complete dry femur specimens,the safe screw placement method to avoid posterior and upper screw penetration in the hollow screw internal fixation of femoral neck fracture was discussed,providing theoretical basis and methodological guidance for the safe and accurate placement of posterior and upper screw in the clinical hollow screw internal fixation of femoral neck fracture.Methods:1.Forty complete dry femur specimens from adults were selected to observe the anatomical and imaging features of the piriform fossa and its lower margin at the base of the upper posterior femoral neck.2.According to the traditional inverted triangle standard screw placement method,lines were drawn on the femur specimen to determine the entry point of the hollow screw guide needle in the lateral wall of the proximal femur,and the guide needles were placed in each femur specimen to observe whether the guide needles penetrated the femoral neck and the imaging performance.3.The safe entry point and the method of needle placement were determined by drawing lines and measuring on the femur specimen to prevent the posterior and upper guide needle from penetrating the femoral neck.4.According to the safe placement method proposed in this study to prevent the posterior and upper guide needle from penetrating the femoral neck,the guide needles were placed in each femoral specimen to observe whether the guide needles penetrated the femoral neck and the imaging performance.5.The various data measured in this study were statistically analyzed with SPSS 26.0 statistical software.Results:1.Anatomical and morphological characteristics of the posterior and upper base of the femoral neck: due to the existence of the pyriform fossa,the bone of the posterior and upper base of the femoral neck has a localized depression,which makes the overall thickness of the femoral neck in the anteroposterior direction here thinner,and its thickness is smaller than the overall thickness of the femoral neck in the anteroposterior direction of other parts of the femoral neck.The high-density shadow formed by the boundary of the pyriform fossa on the anteroposterior X-ray shows a special imaging sign,which is similar to the sign of "big comma".The lower edge of the pyriform fossa shows the sign of "big comma tip".2.The guide needles are inserted according to the traditional inverted triangle standard method.The posterior and upper guide needle is easy to penetrate from the piriform fossa at the posterior and upper base of the femoral neck.The penetration rate of the guide needle is 80%(32/40).The three guide needles on the X line of the anteroposterior position show that the two guide needles at the upper anterior and the upper posterior are parallel and overlapped,and are attached to the upper cortex of the femoral neck,and the lower guide needle is parallel to the upper guide needles,and is attached to the lower cortex of the femoral neck.The punctured upper and posterior guide needle was located in the femoral neck without puncturing the bone of the femoral neck on the anteroposterior and lateral X-ray.3.The safe insertion method to prevent the upper posterior guide needle from penetrating the femoral neck: the insertion point of the upper posterior screw guide needle moved parallel to the level of 5mm below the lower edge of the pyriform fossa compared with the traditional method.The measured safe insertion point was(8.00 ± 0.53)mm from the posterior edge of the lateral wall of the proximal femur,and(12.53 ± 0.62)mm from the top of the slope.The guide needle is placed along the long axis of the femoral neck and the direction parallel to the anterior cortex of the femoral neck from the safe insertion point,that is,the anteversion direction,to prevent the guide needle from penetrating the posterior and upper cortex of the femoral neck,so as to achieve the goal of safe insertion.4.According to the safe needle placement method in this study,the puncture rate of the upper posterior guide needle is 5%(2/40).On the anteroposterior X-ray,it was shown that the upper posterior guide needle and the upper anterior guide needle no longer overlapped the upper cortex of the femoral neck,but moved down parallel to the level slightly below the lower edge of the pyriform fossa.On the lateral image,it was close to the posterior cortex of the femoral neck in the bone.5.Statistical results: The measured data are consistent with normal distribution(P>0.05).The distance between the anterior and posterior edges of the proximal lateral wall of the femur was(21.97 ± 1.70)mm;The distance from the safe insertion point to the posterior edge of the proximal lateral wall of the femur is(8.00 ± 0.53)mm;The distance from the safe insertion point to the top of the slope is(12.53 ± 0.62)mm,and the narrowest diameter of the femoral neck is(24.42 ± 1.69)mm;The widest diameter of the femoral neck is(31.94 ± 1.97)mm.There is a linear correlation between the distance from the safe insertion point to the posterior edge of the proximal lateral wall of the femur and the distance between the anterior and posterior edges of the proximal lateral wall of the femur.The linear regression equation is: y=2.22+0.26 x,and the determination coefficient(R~2)is 0.698,the fitting effect is good.There is a linear correlation between the distance from the safe insertion point to the top of the slope and the distance between the anterior and posterior edges of the proximal lateral wall of the femur.The linear regression equation is:y=7.28+0.24 x,and the determination coefficient(R~2)is 0.423,and the fitting effect is good.The measured data have positive correlation,and the correlation coefficient is between 0.554 and 0.867,which is statistically significant(P<0.05).The correlation coefficient thermodynamic diagram shows strong correlation.Conclusions:1.According to the traditional inverted triangle standard screw placement method,the incidence of "in-out-in" phenomenon is high when the upper posterior screw penetrates the upper posterior cortex of the femoral neck,while the penetrated screw forms a false image in the femoral neck on the X ray of the anteroposterior and lateral positions.2.The safe placement method proposed in this study to prevent the upper posterior screw from penetrating the femoral neck is to move the insertion point of the upper posterior screw guide needle parallel to the level of 5mm below the lower edge of the pyriform fossa compared with the traditional method.The safe insertion point is(8.00 ± 0.53)mm from the posterior edge of the lateral wall of the proximal femur,and(12.53 ± 0.62)mm from the top of the slope.When the upper posterior screw guide needle is placed in the actual operation,in order to prevent the guide needle from penetrating,it should be ensured that the guide needle is located slightly below the mark point of the lower edge of the pyriform fossa on the X-ray image of the anteroposterior position,and close to the posterior cortex of the femoral neck on the lateral image.3.The screw placement method proposed in this study can effectively prevent the upper posterior screw from penetrating the femoral neck and make the screw achieve the effect of edge-fitting fixation.It is a practical,simple,safe and effective method.