Impact of stance width on ankle and hindfoot alignment in varus knee osteoarthritis: A radiographic analysis

Knee osteoarthritis (KOA) often leads to lower limb malalignment, affecting adjacent joints such as the ankle and hindfoot. Although previous studies have examined ankle and hindfoot alignment measurements for KOA, the impact of stance width on these measurements remains unclear. This study investigated the influence of stance width on ankle and hindfoot alignment and evaluated the consistency of radiographic measurements under different stance conditions. Forty-six patients (92 limbs) undergoing total knee arthroplasty for varus deformity were assessed using full-length standing posteroanterior radiographs in open leg (shoulder width) and closed leg (feet in contact) positions. The intertalar distance (ITD), hip–knee–ankle angle (HKAA), tibial plafond inclination angle (TPIA), talar tilt (TT), hindfoot alignment angle (HAA), and mechanical ankle joint axis point (MAJAP) were measured and compared between the two stance conditions, and the variance in the ITD was analyzed to identify the stance providing more consistent measurements. All parameters significantly differed between the two stance conditions except HKAA. ITD significantly correlated with the TPIA, HAA, and TT but not with MAJAP. The variance in the ITD was significantly lower in the closed leg stance group ( p = 0.0298), suggesting greater measurement consistency. The stance width significantly influences ankle and hindfoot alignment measurements. The closed leg stance was associated with a lower ITD variability, making it preferable for standardized imaging. These findings highlight the importance of standardizing foot positioning during adjacent joint alignment assessment to improve the accuracy and reproducibility of measurements in varus KOA. • Stance width affects ankle and hindfoot alignment in varus knee osteoarthritis. • Closed leg stance shows lower measurement variability. • Standardizing foot positioning improves measurement accuracy.