Comparison of two-dimensional and three-dimensional preoperative planning measurements for high tibial osteotomy

Background Open-wedge high tibial osteotomy (OWHTO) is an effective treatment for knee osteoarthritis(KOA). Notably, two-dimensional (2D) preoperative planning for HTO relies on radiographs, possibly disregarding the individual two-dimensional (3D) anatomical differences, whereas 3D; on the other hand, 3D orthopaedic planning uses individualised 3D models and considers the shape of the bones; however, further research is needed to verify its effectiveness. Nevertheless, HTO remains an effective means for KOA treatment, and 2D and 3D preoperative planning is expected to play an important role in the future. However, research on the accuracy of 2D and 3D preoperative planning for HTO is limited. Consequently, this study aimed to compare the differences in 2D and 3D preoperative planning measurements for HTO. Methods Patients with unicompartmental medial KOA and deviation of the mechanical axis of the lower limbs who underwent OWHTO between January 2021 and August 2022 were retrospectively examined. The 3D and 2D preoperative planning of OWHTO was performed by setting the percentage of the weight-bearing line (%WBL) at 62.5% as an optimal alignment. Differences in the correction angle and distraction distance between the two surgical plans were statistically compared. Results Overall, 102 patients were included in the study. The mean correction angle of 2D planning was significantly higher than that of 3D planning (P < 0.001), and the mean difference between the two was 1.49 ± 1.70°. The difference between the two methods in the medial opening gaps for OWHTO was 2.1 ± 2.06mm. Conclusions In conclusion, 2D preoperative planning of OWHTO needs more angle and a larger medial opening gap than 3D planning when aiming at the same WBL. Therefore, surgeons should carefully consider the differences between 2D and 3D preoperative planning and estimate the possible correction error during surgery when planning an OWHTO.