PURPOSE: This study aimed to evaluate the effect of lateral closing-wedge high tibial osteotomy (LCW-HTO) and medial closing-wedge distal femoral osteotomy (MCW-DFO) on tibio-talar inclination (TTI) and Mikulicz lateral distal tibial angle (M-LDTA). We hypothesized that knee osteotomies significantly alter ankle coronal alignment by modifying TTI and distal tibial alignment in relation to the mechanical axis. METHODS: A retrospective radiographic analysis was conducted on 60 knees from 52 patients (37 LCW-HTO and 23 MCW-DFO) treated between 2006 and 2020. Inclusion criteria included full-length weight-bearing radiographs pre- and post-operatively, no prior ipsilateral lower limb surgery, absence of shaft deformities or advanced ankle osteoarthritis (Takakura grade >
1), and age ≥16 years with ≥2 years of follow-up. Radiographic parameters measured included LDTA, hip-knee-ankle angle, M-LDTA and TTI, with ankle realignment quantified through differences between LDTA and M-LDTA and between pre- and post-operative TTI. RESULTS: In the MCW-DFO group, the difference between LDTA and M-LDTA decreased from 3.5 ± 2.3° to 1.3 ± 1.1° ( CONCLUSION: Knee osteotomies significantly influence ankle coronal alignment, particularly modifying TTI and M-LDTA. Higher-level osteotomies (MCW-DFO) exert a greater effect on ankle alignment than LCW-HTO. Preoperative valgus or varus knee deformities must be carefully evaluated to anticipate post-operative ankle imbalance. Surgeons should assess full-length radiographs to prevent unintended malalignment. LEVEL OF EVIDENCE: Level III.