A Comparative Study Of Lower Limb Force Line Measurement Using Two-Dimensional And Three-Dimensional Methods For The Same Body

Objective: This study aims to simultaneously use the two_dimensional(2D)method of measuring lower extremity lines,ie,full_leg standing radiographs(FLR)and three_dimensional(3D)new technique measures the lower limb line,specifically including CT DICOM_computer_aided navigation surgery(CT_CAS);low_dose radiation dual_plane X_ray(low_dose radiation dual_plane X_ray,EOS imaging system)and the use of the Patient Specific Instrument MRI(PSI_MRI)for the mechanical leg axis angle of the lower limb of the same individual one week before and two months after surgery,MLA)to measure,analyze whether the measurement results are different,and thus better guide clinical diagnosis,surgical planning and postoperative follow_up work.Methods: From June 2016 to April 2018,in the Department of Sports Medicine,Zhongshan Hospital,Dalian University,the primary single_chamber knee osteoarthrit is(Osteoarthritis,OA)was caused by poor lower limb line,and the medial open w edge_shaped humerus was accepted.Patients with the medial open wedge high tibia l osteotomy(MOW_HTO)or the distal femoral osteotomy(DFO)were retrospective ly analyzed for their imaging data.A total of 30 cases(30 knees: 10 males and 20 females)were measured by 3 observers(master knowledge of lower limb line me asurement,two chief physicians,one attending physician)for one week before surge ry and 6 months after surgery.The angle MLA between the mechanical axes of th e lower limbs of the patient(ie hip_knee_ankle angle HKA),the clinical standard l ower limb line measurement method FLR as the gold standard for this test,CT_C AS,The EOS imaging system and PSI_MRI measure the lower limb force line of the same individual,respectively,and use the linear regression to perform statistical processing with its difference with respect to the gold standard,that is,the absolut e difference as a reference index.Results: MLA comparisons measured one week before surgery: differences between FLR and CT_CAS(Mean 2.3°,SD 6.4°);differences in FLR and EOS(Mean 1.9°,SD 5.3°);differences between FLR and PSI_MRI(Mean2.5°,SD 6.9°).MLA comparisons were measured half a year after surgery: there was a difference between FLR and CT_CAS(Mean 1.7°,SD 4.4°),and there was a difference between FLR and EOS(Mean 1.4 °,SD 2.8°).Linear regression showed that for the same individual,the MLA was measured by two_dimensional and multiple three_dimensional methods,and the measurement results were different.The postoperative difference was smaller,and the difference between FLR and EOS was the smallest,and between FLR and MRI.Conclusion: For the same individual,the angle between the mechanical axis of the femur and the mechanical axis of the tibia obtained by measuring the lower limb line by two_dimensional and three_dimensional methods is different.The preoperative difference is greater than the postoperative difference.Although PSI_MRI reduces the risk of radiation,the difference between FLR and PSI_MRI is the biggest.It is not recommended to use PSI_MRI instead of FLR to measure the lower limb line.The difference between FLR and EOS is the smallest,and it can be obtained.Knee flexion,recurve angle and angle of patella and femur rotation can better guide knee osteotomy,so it is recommended to use EOS to measure the lower limb line.