The Study Of Tibial Rotation In Patients With OA And Healthy Subjects In South Of China

BackgroundWith the aging of the population,knee osteoarthritis(OA)had become a common disease in the elderly.Due to the structural changes of the knee joint caused by various factors,drug treatment can only partially relieve the pain caused by knee arthritis and can not improve the function of the knee.Total knee arthroplasty(TKA)has been widely used in the treatment of end-stage OA.In total knee arthroplasty,the rotation alignment of the tibia is particularly important.Poor rotation of tibia will lead to postoperative complications,such as pain,joint stiffness and poor patellar trajectory,which greatly reduces the life span of the prosthesis and increases the burden of patients.Most of the previous research objects are European or American people,lack of research on Chinese objects,and previous studies are mostly based on normal people,lack of research on OA.In this study,patients with OA were compared with healthy volunteers based on the population in South China.In addition,most of the previous studies are based on CT measurements,which are easily affected by the thickness of CT,and some anatomical markers are not easy to identify.This study was based on a three-dimensional model,and the accuracy is higher than that of traditional measurements.ObjectiveBased on our clinical experience,a new reference axis of tibial rotation is proposed,and the reliability of the new reference axis is verified by comparing the new axis with the widely used axis.MethodFrom January 2018 to June 2020,a total of 160 patients and normal subjects who were hospitalized in General Hospital of Southern Theatre Command for knee OA and planned to undergo TKA were collected.The full-length CT images of their lower limbs were collected,and the three-dimensional model of tibia was reconstructed from three-dimensional CT data to simulate the operation of TKA,the hyperplastic osteophytes around tibial plateau was removed.The coordinate system was established according to the mechanical axis of the tibia,and base on this coordinate system,the angles between Akagi line,1/3 line,lateral-eminence line(LE line),medial lateral-eminence line(Mle line)and Z axis of the coordinate system were measured.The posterior inclination angle of the tibial plateau was measured,and under the coronal view,the internal inclination angle of the tibial plateau was measured.T-test was used to compare the differences of the above measurement parameters between normal subjects and knee OA patients and between different genders.Pearson correlation coefficient was used to analyze the relationship between tibial rotation reference axis and tibial internal inclination angle.When P<0.05,it was considered that there was statistical difference.ResultThe mean angle between Akagi’s line and Z-axis in healthy group and OA group was 87.57°±3.48°and 87.61°±3.47°,respectively.The mean angle between lateral-eminence line and Z-axis in healthy group and OA group was 87.15°±4.13°and 86.78°±3.95°,respectively.There was no significant difference between Akagi’s line and lateral-eminence line in healthy group and OA group(P<0.05).A weak correlation was found between the intersection angle and the mean angle between Akagi’s line,1/3 line and Z-axis.A moderate correlation was found between the intersection angle and the mean angle between lateral-eminence line and Z-axis.ConclusionThe lateral-eminence line that were studied showed excellent intra/inter-observer reliability and reproducibility.The novel and easily drawn lateral-eminence line showed strong correlation with the Akagi’s line and could be used for tibial component rotational alignment in TKA.