Leaving Mild Varus Leads To Better Clinical Outcome After Total Knee Arthroplasty In Patients With Lateral Femoral Bowing

Objective:Some studies documented that residual varus alignment leads to better patient function and higher satisfaction score for patients with constitutional varus after total knee arthroplasty(TKA).It is uncertain,however,whether undercorrection of lateral femoral bowing will result in better outcome for patients with this specific constitutional varus.Methods:A retrospective review of a prospectively maintained database were performed.71 knees of 59 patients with a femoral bowing angle(FBA)>3°operated on by same surgeon between January and December 2015 were included in the study.A total of 64 patients with 78 knees were screened out,among which 3 were lost to follow-up and 2 died.A total of 59 patients with 71 knees were obtained.Patients were divided into two groups according to the postoperative HKA angle from weight-bearing full-leg radiographs: varus malalignment group(37 cases HKA <177°);neutral alignment group(34 knee HKA was180 ° ± 3 °).The Knee Society Score(KSS)and the Western Ontario and Mc Master Universities Arthritis Index(WOMAC)were compared between preoperative and minimum49.3-month postoperative time-point between groups.Results:The mean follow-up time was 49.3 months.No revisions occurred in any of the groups at midterm follow-up.There were no statistical differences in demographic data such as age,sex,weight,height,and BMI between the two groups,no statistical difference in preoperative scores.All patients improved between preoperative and post-operative timepoints(p<0.05).Patients with varus malalignment and neutral alignment were comparable on KSS score and KSS functional score.However,the varus malalignment group demonstrated significant lower WOMAC total score and part C score than the neutral alignment group(5.57±6.230 Vs 9.27±8.864,4.95±5.869 Vs 8.24±7.683,respectively.P<0.05).Conclusions:For patients with lateral femoral bowing,residual varus alignment leads to better clinical outcomes after TKA than neutral alignment at a mean follow-up of 49.3 months.However,The effect of residual varus alignment on the survivalship of the prosthesis andthe long-term outcome needs to be further evaluated.