The Effect of Total Knee Arthroplasty on Hindfoot Alignment in Patients with Severe Genu Varum and Genu Valgum

Background: The maintenance of deformity in the ankle and hindfoot after correction of knee deformity following kneearthroplasty may cause abnormal tension in the knee and patient dissatisfaction. The aim of this study was to determinethe effect of knee arthroplasty on the hindfoot alignment in patients with severe genu varum and valgum.Methods: A total of 84 patients with primary osteoarthritis, were enrolled in the study. The knee deformity was measuredusing a long leg film before surgery. The long axial radiographic view of hindfoot was taken in the standing position forall patients, before and six months after surgery. Comparisons were made on changes in the hindfoot angles measuredbefore and after surgery.Results: A total of 84 patients with mean age of 62.28 ± 7.77 years, 77 (92%) and seven patients (eight percent)had knee varus and valgus deformity, respectively. In the knee varus group, the mean preoperative hindfoot anglewas + 5.32 ± 6.12 ° (valgus) which was changed to - 0.25 ± 4.91 ° (varus) in the postoperative phase. In the kneevalgus group, the mean pre and postoperative hindfoot angles were - 7.71 ± 7.06° (varus) and - 2.14 ± 5.92 ° (varus),respectively. The mean preoperative hindfoot angle in severe and very severe varus knee groups were + 5.45 ± 3.30and + 5.28 ± 6.86 °, respectively. These angles were changed to + 0.21± 5.17 and -1.60 ± 3.89° six months aftersurgery, respectively. The mean preoperative hindfoot angle in severe and very severe valgus knee deformity groupswere - 7.00 ± 4.69 and -8.66 ± 10.69 °, respectively. These angles were changed to - 2.00 ± 5.71 and - 2.33 ± 7.50°after surgery, respectively. There was no significant difference between patients with severe and very severe deformityin terms of pre and post-operative hindfoot angle.Conclusion: The hindfoot alignment is significantly corrected after knee arthroplasty. The severity of knee deformitydoes not correlate with the severity of the hindfoot deformity before and after surgery.Level of evidence: I