Knee osteotomies significantly influence coronal ankle alignment: A radiographic analysis

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° (p < 0.0001), indicating improved alignment. The LCW-HTO group showed a smaller but significant reduction from 4.5 ± 1.8° to 2.2 ± 1.7° (p < 0.0001). TTI improved significantly in both groups, with a greater adjustment in MCW-DFO (ΔTTI = 7.0 ± 4.3°, p < 0.01) compared to LCW-HTO (ΔTTI = 4.2 ± 2.7°, p < 0.01). The difference between LDTA and TTI decreased in both groups, reflecting post-operative convergence of the mechanical and anatomical axes. 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.