The Anatomical Marker For Femoral Neck Osteotomy In Direct Anterior Approach For Total Hip Arthroplasty Based On The Three-dimensional Imaging Analysis

Bcakground:Accurate femoral neck osteotomy that is an important step in direct anterior approach（DAA）for hip arthroplasty: determines the articulation of the acetabulum and determines whether the femoral stem can be inserted in the correct direction.Wrong osteotomy will lead to the wrong direction of femoral prosthesis and lead to femur splitting.Or the wrong size of the femoral stem may cause long-term loosening.Unlike the posterolateral approach,which can expose and reference lesser trochanter,while the DAA approach does not have good bony or soft tissue markers in front of the femoral neck to determine the location of osteotomy.The only reference is usually the intertrochanteric line or the saddle of the upper femoral neck,while the osteotomy site in the saddle area and the location of the intertrochanteric line are not easy to accurately determine during the operation.In a large number of DAA procedures,we find that there is actually a relatively constant anatomic marker in front of the femur: the tubercle of the superior band of the iliofemoral ligament（TSIFL）can be used as a reference marker for the location of osteotomy.Objective:To investigate the incidence,size,and relationship of TSIFL with other important anatomical markers,such as greater trochanter,femoral neck saddle area,femoral head center,and obturator externus muscle attachment.Method:From September 2019 to September 2021,a total of 185 patients（96 males and89 females,mean age: 61.7±11.5 years）underwent preoperative femoral full-length thin layer CT plain scanning before total hip arthroplasty due to femur head necrosis in our department.By Mimics（V.19.0,Materialise,Leuven,Belgium）3D femur reconstructed.2D and 3D methods were used to mark TSIFL,vertex of greater trochanter,saddle area of femoral neck,center of femoral head,and attachment point of obturator externus muscle,etc.Measure the spatial position relationship between TSIFL and these markers.The measurements were analyzed using SPSS（V25.0,Chicago,IL,USA）.Result:The vertical distance between the TSIFL center and the coronal position of the apex of the greater trochanter was significantly different between males and females（23.51±4.50 mm in male;Female 21.90±4.41 mm,P = 0.015）;There was a significant difference in the coronal distance of the TSIFL center from the femoral head in males and females（44.57±3.62 mm in male;Female 37.76±3.43 mm,P <0.001）;The vertical distance from the TSIFL center to the obturator externus insertion coronal perspective was significantly different between males and females（-3.16±6.15 mm in male;Female-0.33±4.25 mm,P < 0.001）;There was no significant difference between males and females in the coronal vertical distance between TSIFL center and femoral neck saddle region,the vertical distance between TSIFL center and femoral head center,the vertical distance between TSIFL center and medial TSIFL edge and the vertical distance between the osteotomy plane and the lesser trochanter.Conclusion:Femoral neck accurate osteotomy is an important step in the DAA for hip replacement,while posterolateral approach can reveal the reference of lesser trochanter for osteotomy.DAA of the femoral neck in front of the no good osseous and soft tissue marks were used to judge the position.In a large number of DAA intraoperative found that front femur actually has a relatively constant TSIFL’s anatomic landmark,which can be used as a reference symbol of osteotomy. The vertical distance between TSIFL center and the insertion of obturator external muscle was significantly different between males and females.It was found in DAA that most DAA femoral neck osteotomy achieved satisfactory results with TSIFL as a reference.Meanwhile,the Angle and plane of femoral neck osteotomy that are influenced by individual differences of patients and surgical experience of operators will be exist a certain differences,and intraoperative osteotomy is performed not only by referring to a single anatomical marker for osteotomy,but also the morphology the proximal femur.This study dedicates to provide a reliable anatomical reference for DAA femoral neck osteotomy.Guidance for DAA intraoperative femoral neck osteotomy’s reference provides a new way of thinking,and improving the accuracy of osteotomy is of great significance.