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

Table 6 Knee deformity thresholds for ankle malalignment probability (°)

Direction	Outcome	50% probability if HKAA	70% probability if HKAA	80% probability if HKAA
Varus knee leading to varus ankle alignment	TTA < 85.9	≤ 175.7	≤ 170.8	≤ 167.6
Valgus knee leading to valgus ankle alignment	TTA > 91.9	≥ 189.2	≥ 192.5	≥ 194.6

Knee deformity thresholds were derived from direction-specific logistic regression models. Varus knees were modeled for varus ankle malalignment [tibiotalar angle (TTA) < 85.9°], and valgus knees were modeled for valgus ankle malalignment (TTA > 91.9°). Thresholds correspond to hip to knee to ankle angle values associated with 50%, 70%, and 80% predicted probabilities of ankle malalignment. HKAA: Hip to knee to ankle angle; TTA: Tibiotalar angle.