High tibial osteotomy (HTO) remains a key joint-preserving option for treating medial knee osteoarthritis with varus deformity, with both closing-wedge (CW-HTO) and opening-wedge techniques delivering long-term, comparable results. While complications are uncommon, hinge fractures—well documented in OW-HTO—remain understudied in CW-HTO despite their potential to compromise correction, healing, and overall outcome.

This study aims to fill that gap by analyzing the incidence and morphological patterns of medial hinge fractures in CW-HTO, proposing a dedicated classification system. Moreover, it investigates whether specific radiological features of the osteotomy line predispose patients to these fractures, offering new insights to refine surgical planning, optimize technique, and reduce complications.