In knee osteoarthritis, what is the knee deformity threshold after which the ankle realigns beyond the neutral zone?

Figure 2 Scatter plots illustrating the relationship between the hip to knee to ankle angle and the tibiotalar angle with shaded neutral zones (hip to knee to ankle angle: 178-182°, tibiotalar angle: 85. 9-91.9°). A: All the patients; B: Varus knees; C: Valgus knees; D: Stratified based on patients’ sex; E: Stratified based on the knee osteoarthritis Kellgren-Lawrence grades. The solid curve represents locally weighted scatterplot smoothing, used to explore non-linear trends without assuming a predefined functional form. A steeper and more consistent trend is observed in varus knees, whereas greater dispersion is seen in valgus knees. HKAA: Hip to knee to ankle angle; TTA: Tibiotalar angle; KL: Kellgren-Lawrence; LOWESS: Locally weighted scatterplot smoothing.