Park JY, et al. - Researchers ascertained the impacts of various preoperative anatomical alignment parameters to the postoperative knee joint line orientation (KJLO). Based on this analysis, they create an equation that anticipates the value of postoperative KJLO. In total, 14 radiographic parameters were measured in preoperative and postoperative full-limb standing anteroposterior radiographs on 50 patients who had open-wedge high tibial osteotomy (HTO). Using multivariable linear regression, the parameters were analysed to predict KJLO after HTO. The equation was externally validated with 20 patients who had HTO at another institution. Investigators found that KJLO increased from − 0.8° to 2.9° after HTO. An equation has been derived that can estimate postoperative G-KJLO after HTO based on the multiple linear regression analysis by stepwise elimination of parameters influencing postoperative G-KJLO. Data reported that the adjusted coefficients of determination value for this equation was 0.721. It is anticipated that this equation will help select optimal patients and HTO operative plan.