Changes in Joint Line Position after Total Knee Arthroplasty and Their Impact on Kinematic Parameters

LI Haibing; LIU Jinhui; LI Hui; YANG Liwen; LIU Xinzhe; WANG Libo

doi:10.3639/j.issn.2095-3097.2025.04.022

Abstract：Objective To investigate the changes in joint line position after total knee arthroplasty(TKA)and their impact on kinematic parameters.Methods A total of 156 patients who underwent TKA in Xingtai Central Hospital from Sep-tember 2022 to September 2023 were selected.Postoperative changes in joint line position were observed.The Visual Analog Scale(VAS)scores for pain,range of motion(ROM),patellar Feller scores,American Knee Society(AKS)scores,and kine-matic parameters of patients with different joint lines positions were compared.The correlation between postoperative joint line changes and kinematic parameters was analyzed.Results Postoperative joint line measurements showed 22 patients with no changes(Group A),49 with changes ≤4 mm(Group B),and 85 with changes＞4 mm(Group C).At 3 and 12 months after sur-gery,VAS scores in group B were lower than those in group A and C,ROM was higher than that in group A and C,and Feller and AKS scores were higher than those in group A and C(P＜0.05).During knee flexion,the tibia internally rotated relative to the femur.Significant differences in anterior-posterior displacement of medial and lateral femoral condyles were observed among the three groups(P＜0.05).Spearman correlation analysis revealed that joint line were negatively correlated with anterior-posterior movement distances of the medial condyle(60°,90°,max angles)and lateral condyle(60°,90°,max angles)(P＜0.05),but not at 30°(P＞0.05).Conclusion Joint line position may change after TKA and is negatively correlated with kinematic parameters.Knee recovery varies among patients with different joint line positions.Long-term monitoring of joint line changes can aid in evaluating and predicting functional recovery.