The effect of total knee arthroplasty on hindfoot alignment in patients with severe genu varum and genu valgum

Introduction: The maintenance of deformity in the ankle and hindfoot after correction of knee deformity following knee arthroplasty may cause abnormal tension in the knee and patient dissatisfaction Materials and methods: A total of 84 patients with primary osteoarthritis, were enrolled in the study. The knee deformity was measured using a long leg film before surgery. The long axial radiographic view of hindfoot was taken in the standing position for all patients, before and six months 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, mean preoperative hindfoot angle was + 5.32 ± 6.12 ° (valgus) and was changed to - 0.25 ± 4.91 ° (varus) in the postoperative phase. In the knee valgus group, 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 ± 3.30 and + 5.28 ± 6.86 °, respectively. These angles were changed to + 0.21± 5.17 and -1.60 ± 3.89° six months after surgery, respectively. The mean preoperative hindfoot angle in severe and very severe valgus knee deformity groups were - 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 deformity in terms of pre and post-operative hindfoot angle. Conclusion: The hindfoot alignment is significantly corrected after knee arthroplasty. The severity of knee deformity does not correlate with the severity of the hindfoot deformity before and after surgery. Level of evidence: I