Application Of Digital Technology In Precise Placement Of Femoral Intramedullary Rod In Total Knee Arthroplasty For Chinese

Purpose:Establish a three-dimensional(3D)model of femur by digital technology,and to find out the best entry point,insertion direction and depth of femoral intramedullary rod in total knee arthroplasty(TKA)for Chinese.Methods:Eighty-five Chinese adult patients with knee osteoarthritis(OA)were collected continuously,including 39 male patients and 46 female patients.3D reconstruction of the femur by CT,establishment of standard 3D coordinate system,3D reconstruction of the femoral condyle cartilage by MRI and bone cartilage fitting of the femoral condyle were carried out by digital technology.Finally,the 3D digital image of the whole femur with the best fitting of the femoral condyle cartilage was obtained.Objective to find the best entry point of femoral intramedullary rod in TKA for Chinese patients with knee OA by reverse engineering technology,and simulate the insertion of femoral intramedullary rod to obtain the best insertion direction and depth of femoral intramedullary rod.Results:1.In this study,we measured the vertical distances from the optimal entry point(E point)of femoral intramedullary rod obtained by reverse engineering to the apex of the intercondylar notch(AIN),Whiteside’s line(WL)and surgical transepicondylar axis(sTEA)in male and female patients with knee OA,respectively.In male patients with knee OA,the vertical distance from E point to AIN,WL and sTEA was 13.52±4.34mm,4.72±2.51mm and 21.00±3.03mm respectively;in female patients with knee OA,the vertical distance from E point to AIN,WLand sTEA was 15.86±2.25mm,-0.33±4.10mm and 21.71 124.47mm respectively.In the comparison of the above three parameters,the vertical distance from E point to WL in male patients with knee OA was significantly greater than that in female patients with knee OA(t=2.744,p=0.023),but there was no statistical significance between the vertical distance from E point to AIN and sTEA(t=-1.646,p=0.134;t=-0.756,p=0.469).2.In this study,we measured the angle between the simulated intramedullary rod and the femoral mechanical axis in male and female patients with knee OA.In male patients with knee OA,the comparison between each group was statistically significant.In TC200,the intersection angle in the range of 0°-5° and 0°-3° is as high as 90%and 97%respectively.In female patients with knee OA,TA200 accounts for 91%and 96%in the range of 0-3° and 0-5° respectively.Conclusion:1.The application of digital technology to obtain 3D images of the whole femur covering the cartilage surface of the femoral condyle can intuitively and accurately locate the bone landmarks of the femoral condyle,and measure the relevant parameters.This paper provides an accurate description of the position and a reliable measurement method for the application of accurate femoral intramedullary positioning in TKA for Chinese adult patients with knee OA.2.Through the 3D model covering the femoral condylar cartilage,the best entry point of femoral intramedullary rod in TKA of Chinese patients with knee OA was found,which provided a reliable methodological basis for the accuracy and personalization of distal femoral osteotomy,and proposed a more reliable,accurate,practical and repeatable entry point for Chinese patients.3.We describe a fast and simple method to determine the insertion angle and depth of femoral intramedullary rod in the sagittal plane during TKA,it can optimize the alignment of femoral prosthesis in the sagittal plane during TKA,and propose a more reliable,accurate and repeatable insertion angle and depth of femoral intramedullary rod for Chinese.