A Study On The Changes In The Force Line Of The Contralateral Knee Joint After Unilateral Knee Arthroplasty In Patients With Bilateral Knee Osteoarthritis

Objective:To study the radiographic changes of limb alignment in contralateral knee after unilateral knee arthroplasty due to knee osteoarthritis and analyze the effect of K-L grade(Kellgren-Lawrence grade)on the radiographic changes of limb alignment in contralateral knee after unilateral knee arthroplasty.Methods:A retrospective review of patients with bilateral knee osteoarthritis treated with unilateral TKA was performed.Patients were subcategorized into group A(K-L grade≤2)and group B(K-L grade>2).Postoperative changes and the differences of limb alignment in contralateral knee between two groups were analyzed and compared.The relation between postoperative radiographic changes of limb alignment in operative knee and contralateral knee were analyzed.Postoperative radiographic changes of limb alignment in contralateral knee was compared between patients under total knee arthroplasty and patients under unicompartmental knee arthroplasty.Results: A total of 157 patients were included in this study.There was no significant difference in basic information between the two groups.Postoperative change of contralateral knee hip-knee-ankle angle improved 0.9±1.2°on average,0.6±1.0° in group A and 1.0±1.3° in group B,and there was significant difference between the two groups(P<0.05).Postoperative change of contralateral knee mechanical axis deviation improved 5.7±12.4mm on average,2.3±7.6mm in group A and 8.0±14.3mm in group B,and there was significant difference between the two groups(P<0.05).The relation between postoperative change of mechanical axis deviation and hip-knee-ankle angle in operative knee and postoperative change of HKA in contralateral knee were in positive correlation respectively(P<0.05).There was no significant difference between postoperative changes of limb alignment in patient under total knee arthroplasty and patients under unicompartmental knee arthroplasty(P>0.05).Conclusion: In patients with bilateral knee osteoarthritis who undergo knee arthroplasty,limb alignment in contralateral knee improved.More change in patients whose K-L grade >2 than patients whose K-L grade ≤2 can be measured.The operative method had no effect on the contralateral limb alignment.Further research is necessary to determine whether this improvement may delay the progression of contralateral knee osteoarthritis.