Association between knee osteoarthritis and foot deformities: epidemiological analysis of hallux valgus and flatfoot

Objective: To investigate the association between knee osteoarthritis (KOA) and the presence of hallux valgus and flat feet. Method: This retrospective study analyzed KOA patients from January 2022 to March 2024, investigating the correlation between KOA and hallux valgus and flatfoot. The diagnosis of KOA and assessment of its symptoms were conducted using the diagnostic criteria and grading system established by the American College of Rheumatology, specifically the Kellgren-Lawrence (K-L) grading system and measurement of the femorotibial angle (FTA). Physical examination, weight-bearing X-ray examination and MRI evaluation of the knee were performed. Foot examination included weight-bearing and lateral X-ray imaging to determine the presence of hallux valgus and flat feet. Results: A total of 168 patients met KOA criteria: 162 with genu varum, 6 with genu valgum and 39 with pes anserine tendinitis. Among those with genu varum, 145 had hallux valgus, 136 had flatfoot and 39 had pes anserine tendinitis. Gender distribution: 37 male (22.02%) and 131 female (77.98%). The mean age was 73.84 +/- 4.96 years. Spearman correlation analysis showed significant associations between the severity of KOA (K-L grade) and hallux valgus (r = 0.681, p < 0.05) and flatfoot (r = 0.689, p < 0.05). Conclusion: There was a significant correlation between KOA, hallux valgus and flatfoot. However, due to the study's cross-sectional design, causality cannot be established. There was also a significant link between knee varus and pes anserine bursitis.