Abstract:Objective To simulate the intramedullary localization process of Oxford unicompartment knee arthroplasty (OUKA) by digital technology,and to analyze the error of intramedullary guide of the rodwith different length by finite element analysis.Methods The patients underwent OUKA from January 2019 to October 2019 in our department were selected prospectively.The three-dimensional model of femur was established by using the software of mimics and 3-matics,and thepositioning process in OUKA was simulated.Two kinds of intramedullary rods with different lengths (30 cm and 20 cm) were inserted respectively.The finite element analysis was carried out by using the software of Ansys.The swinging of the intramedullary rod in the intramedullary cavity was simulated,and the distance of the rod end moving was obtained.The maximum distance and the maximum displacement of the rod end in the sagittal and coronal plane of the intramedullary cavity were calculated.The data were analyzed statistically.Results The maximum swing range of 30 cm rod was (1.10±0.72)degrees in sagittal plane of the femoral medullary and (0.85±0.55)degrees in coronal plane,while (4.36±0.95)degrees in the sagittal and (3.77±1.00)degrees in the coronal of 20 cm rod.The maximum swing range of the same rod in sagittal plane was larger than that in coronal plane,and the difference was significant (P<0.05).On the sagittal and coronal plane,the maximum swing range of 30 cm rod was significantly smaller than that of 20 cm rod (P<0.05).There was a significant correlation between the swing range of 30 cm and 20 cm rods.Conclusion In this study,a finite element model of the movement of the rod in the marrow cavity is established.It is proved that the error of the 30 cm rod is significantly less than that of the 20 cm rod,and its positioning is more accurate.However,for patients in small size,it is possible that the intramedullary rod cannot be completely inserted or deformed after insertion.For these patients,we recommend 20 cm rod.
[1]Ollivier M,Jacque C,Lucet A,et al.Long-term results of medial unicompartmental knee arthroplasty for knee avascular necrosis [J].J Arthroplasty,2019,34(3):465-468.
[2]Kim KT,Lee S,Lee JI,et al.Analysis and treatment of complications after unicompartmental knee arthroplasty[J].Knee Surg Relat Res,2016,28(1):46-54.
[3]Kim JG,Kasat NS,Bae JH,et al.The radiological parameters correlated with the alignment of the femoral component after Oxford phase 3 unicompartmental knee replacement [J].J Bone Joint Surg (Br),2012,94(11):1499-1505.
[4]Tu Y,Xue H,Ma T,et al.Superior femoral component alignment can be achieved with Oxford microplasty instrumentation after minimally invasive unicompartmental knee arthroplasty[J].Knee Surg Sports Traumatol Arthrosc,2017,25(3):729-735.
[5]Gulati A,Weston-Simons S,Evans D,et al.Radiographic evaluation of factors affecting bearing dislocation in the domed lateral Oxford unicompartmental knee replacement[J].Knee,2014,21(6):1254-1257.
[6]Liu SL,Liu LB,Zuo JL,et al.Three dimensional reconstruction and measurement of the proximal femur in adult developmental dysplasia of the hip[J].Zhonghua Wai Ke Za Zhi,2016,54(4):264-269.
[7]Tawada K,Iguchi H,Tanaka N,et al.Is the canal flare index a reliable means of estimation of canal shape Measurement of proximal femoral geometry by use of 3D models of the femur [J].J Orthop Sci,2015,20(3):498-506.
[8]Kang KT,Son J,Baek C,et al.Femoral component alignment in unicompartmental knee arthroplasty leads to biomechanical change in contact stress and collateral ligament force in knee joint [J].Archives Orthop Trauma Surg,2018,138(4):563-572.
[9]蔡俊丰,马敏,罗树林,等.数字化技术在控制膝关节单髁置换股骨假体力线精确性中的应用 [J].同济大学学报(医学版),2017,38(6):81-86.
[10]Su XY,Zhao Z,Zhao JX,et al.Three-dimensional analysis of the curvature of the femoral canal in 426 chinese femurs [J].Biomed Res Int,2015(2015):318391.
[11]Yang T,Tu Y,Xue H,et al.Imaging study on effect of femoral intramedullary guide on the alignment of femoral prosthesis in unicompartmental knee arthroplasty[J].Zhongguo Xiu Fu Chong Jian Wai Ke Za Zhi,2019,33(1):8-12.
[12]蔡俊丰,马敏,罗树林,等.单髁关节置换中股骨髓内定位杆插入点的解剖学研究[J].中华关节外科杂志(电子版),2017,11(5):511-515.