Correlation Between The Difference Of Anterior Femoral Arch Angle And The Choice Of Insertion Point Of Intramedullary Nail For Intertrochanteric Fractures

Objective To determine the optimal insertion point of the intramedullary nail under the condition that the intramedullary nail is completely matched with the femoral bone cavity,and to study the relationship between the difference in the angle of the anterior arch of the femur and the selection of the optimal insertion point for clinical determination an ideal intramedullary nail insertion point,especially when the angle of the anterior arch of the femur is large,provides a good intramedullary nail position to provide theoretical and data support.Methods 200 cases(84 males and 116 females,aged 51-93 years,mean age 80.15 years)of CT scan data were imported into Mimics 19.0 for 3D femoral modeling,and all 3D models of femurs after modeling were collected.Make anterior bow angle measurement and record parameters.Proe5.0 three-dimensional drawing software was used to perform three-dimensional virtual reconstruction of nine types of intramedullary nail data.Proximal Femoral Nail Antirontation(PFNA)was reconstructed.Then,the reconstructed internal fixation model was imported into the 3D femur by simulating the surgical process,and the specific position was adjusted.After the internal fixation was introduced,the proximal head was embedded into the top of the great trochanter.Meet the requirements of surgical guidelines.In the case that the intramedullary nail is completely matched with the femoral bone marrow cavity,the proximal head of the intramedullary nail can be regarded as a standard circle,and the center of the circle is the optimal insertion point E,and the trochanter is defined.For G,observe the position of the optimal needle point E on the top view of the femur,and record the distance EG between the optimal needle point E and the trochanter G.The top view coordinate system of the optimal insertion point is set with the large tuberosity vertex G as the origin,and a scatter plot of all the optimal insertion points E in different front bow angle groups in the top view coordinate system is drawn.Statistical analysis was performed to explore the relative changes in the EG distance in different anterior arch angle groups,and the trend of the distribution of the optimal needle insertion point E in the anterior arch angle group.Results In the retrospective analysis,the distance between the best needle insertion point and the trochanter’s apex was in the anterior arch angle of the femur(7-9)°,(10-12)°,(13-15)°,(16-18)° were(6.73 ± 2.32),(7.91 ± 3.27),(8.46 ± 3.49),and(4.52 ± 1.25)mm,the difference was significant(P<0.05);the patients in the four groups of anterior arch angle group there was a significant difference in age distribution(P<0.05).As the age increased,the anterior arch angle of the femur also increased.Second,the patients in the four groups of anterior arch angle had significant differences in gender distribution(P<0.05),female patients usually have larger anterior arch angles.Conclusion On the premise that the main nail of the intramedullary nail is completely matched with the femoral bone marrow cavity,the greater the angle of the anterior arch,the greater the distance between the intramedullary nail insertion point and the backward movement.For femoral intertrochanteric fractures,the anterior arch angle of the femur is measured before surgery to optimize the choice of PFNA needle insertion point,so that the intramedullary fixation system is closer to the lower limb force line.It has stability for fracture fixation,bone healing and early limb bearing Obvious biomechanical advantages.