Structural and pathological adaptations in the foot and ankle of patients with bilateral knee osteoarthritis: association with foot posture and magnetic resonance imaging findings

INTRODUCTION: The biomechanical relationship between the foot and knee affects joint stress, and foot posture has been associated with the presence and progression of knee osteoarthritis (KOA). Few studies have examined foot posture and tendon morphology together in patients with KOA. PURPOSE: This study aimed to investigate foot posture, pathologies of the foot-ankle complex, and the cross-sectional area (CSA) of tendons in patients with KOA. We also evaluated whether these findings varied by KOA severity and foot posture. METHODS: This cross-sectional observational study included 84 patients with bilateral KOA (62 female, 22 male; 168 knees), diagnosed by physical examination and radiography. KOA severity was classified using the Kellgren - Lawrence (KL) system (KL1: 40, KL2: 83, KL3: 41, KL4: 4). Patients were grouped as mild KOA (KL1-2) or severe KOA (KL3-4). Magnetic resonance imaging was used to detect foot and ankle abnormalities and to evaluate the tendon cross-sectional areas. Data were analyzed based on foot posture, and KOA severity. CONCLUSION: The high incidence of multiple pathologies in the foot-ankle complex, even in patients with neutral foot position, highlights significant connection with KOA. Our findings regarding specific correlations and tendon CSA differences suggest that the foot-ankle complex should be key consideration in the treatment planning for patients with KOA.