Effects of high tibial osteotomy on the coronal, sagittal, and axial alignments of the ankle joint.

Background: No comprehensive study has been conducted on the effects of high tibial osteotomy (HTO) on the coronal, sagittal, and axial alignments of the ankle joint. Therefore, this study aimed to investigate the multiplane changes in the ankle joint following HTO using the EOS biplanar X-ray imaging system.

Methods: The medical records of 43 patients who underwent HTO for the treatment of medial knee osteoarthritis were retrospectively reviewed. Preoperative and postoperative EOS images and lower-extremity scanograms were evaluated; the correlations between the outcomes were evaluated.

Results: After HTO, the ankle joint axis point on the weight-bearing line showed significant lateralization (p < .001). The knee lateral ankle surface angle increased significantly in the sagittal alignment (p < .001). The distal tibia showed a significant internal rotation in the axial plane (p = .022). Tibial rotation showed no significant relationship with the other parameters.

Conclusions: HTO induced lateralization of the ankle joint axis (coronal), increased the posterior tibial slope (sagittal), and caused the internal rotation of the distal tibia (axial). Axial changes in the distal tibia showed no significant relationship with other coronal and sagittal parameters of the ankle joint. We suggest that surgeons should consider, during HTO, that the ankle joint axis shifts laterally and distal tibia has tendency to rotate internally after HTO.