膝外翻矫形术中股骨远端不同截骨角的生物力学实验研究OACSTPCD

Objective To explore the biomechanical characteristics of different orthopedic angles at distal femora in genu valgum treated with distal femur osteotomy(DFO).Methods The MRI and CT image data of a typical female volunteer with supracondylar femur deformity and symptomatic genu valgum were collected to construct a three-dimensional bone-joint finite element model of genu valgum,with seven postoperative models at different orthopedic angles.The mechanical lateral distal femoral angle(mLDFA),medial proximal tibial angle(MPTA),mechanical femorotibial angle,and lower limb alignment crossing distance of the genu valgum model were measured.The redistribution of contact force and von Mises stress of knee cartilage and meniscus in the medial and lateral compartments of knee joint in standing extension were observed and analyzed.Results The lower limb alignment crossing distance was obviously affected by the orthopedic angle,which crossed the 50%boundary at the orthopedic angles of 6° to 7°.The mechanical femorotibial angle was affected by the orthopedic angle,which gradually turned negative at the orthopedic angles of 5° to 6°.MPTA was not affected by the orthopedic angles.mLDFA was affected by the orthopedic angle,the mLDFA increased by 1°with every 1° increase in the orthopedic angle.When the orthopedic angle on the coronal plane was 7°,the femoral-tibial mechanical axis crossed through 48.6%of the coronal plane of the knee joint space,the contact force distribution of the medial and lateral compartments of the knee joint was 40%on the lateral compartment,and 60%on the medial compartment,the von Mises stresses distribution of articular cartilages on the medial and lateral compartments were the most uniform,the peak stress on the lateral compartment of the femoral cartilage of the knee joint was 5.2 MPa,with 5.5 MPa on the medial compartment,and the peak stress on the lateral compartment of the tibial side was 6.0 MPa,with 6.2 MPa on the medial compartment.Conclusion The orthopedic angle has a significant effect on the redistribution of medial and lateral compartment contact force and cartilage stress in the treatment of genu valgum with DFO.After orthopedics,the femoral-tibial mechanical axis crosses slightly medial to the midpoint of the tibial plateau,with a slight varus,the stress distribution of articular cartilage is more balanced,and the contact force distribution of the medial and lateral compartments are close to the normal state of the human knee joint.