Modification of the coronal plane alignment of the knee classification considering the joint line convergence angle in high tibial osteotomy: a geometric approach

Abstract Background Excessive joint line obliquity (JLO) is associated with poor outcomes in open wedge high tibial osteotomy (OWHTO). The Coronal Plane Alignment of the Knee (CPAK) classification categorizes knee phenotypes by alignment and JLO but overlooks the joint line convergence angle (JLCA), which impacts JLO pre- and postoperatively in OWHTO. This study aims to modify JLO calculation by incorporating JLCA through a geometric approach, with the goal of better reflecting the knee joint or