Determinants of Achilles tendon thickness and their influence on knee function and foot alignment in knee osteoarthritis

Abstract Knee osteoarthritis (OA) significantly impacts the quality of life of individuals globally. However, the interconnections between Achilles tendon thickness, knee symptoms/functions, and foot alignment remain understudied in knee OA patients. This study determines the relationships between Achilles tendon thickness (ATT), knee symptoms/functions, and foot alignment in knee OA patients, considering their interconnected biomechanical nature. In a cross-sectional analysis involving 122 knee OA patients, Knee injury and Osteoarthritis Outcome Score (KOOS) assessed knee function and symptoms. Forefoot, midfoot, and rearfoot alignment were measured using hallux valgus angle, navicular/foot ratio, and rearfoot angle. The navicular/foot ratio represented the ratio of navicular height to total foot length. ATT was measured using a digital calliper. Pearson correlations and stepwise multiple linear regression models were employed to explore relationships and determinants. Out of 122 participants, 88 (72.1%) were females. ATT correlated significantly with ankle range of motion, forefoot alignment, and midfoot alignment. In stepwise multivariable regression, ankle range of motion, navicular/foot ratio, and age were significantly associated with ATT (adjusted R 2 = 0.44). Similarly, KOOS-Symptoms scores were linked to the OA severity, navicular/foot ratio, ankle range of motion, gastrocnemius strength, and age (adjusted R 2 = 0.22). KOOS-Function scores were significantly associated with knee OA severity, gastrocnemius strength, ankle range of motion, and age (adjusted R 2 = 0.19). Midfoot alignment was significantly associated with ATT and knee symptoms in patients with Knee OA. This suggests potential benefits of interventions targeting both Achilles tendon properties and foot alignment for improved knee OA outcomes.