Opposite cortical fractures in closed-wedge HTO: New classification and treatment algorithm

Area of Science:

• Orthopedic surgery
• Biomechanics
• Radiology

Background:

• Intact opposite cortex (OC) is crucial for high tibial osteotomy (HTO) stability.
• Identifying opposite cortical fracture (OCF) types is vital for predicting mechanical complications.
• This study aims to classify OCFs in CWHTO and develop a treatment algorithm.

Purpose of the Study:

• To establish a classification system for opposite cortical fractures (OCFs) in closed wedge high tibial osteotomy (CWHTO).
• To correlate OCF types with the incidence of mechanical complications.
• To propose a treatment algorithm based on the OCF classification.

Main Methods:

• Retrospective analysis of clinical and radiological results from 187 angle-stable navigated CWHTOs.
• Classification of OCFs into two main types based on fracture line direction.
• Subclassification into three subtypes (A-nondisplaced, B-primarily displaced, C-secondarily displaced).

Main Results:

• Type 1 OCFs were predominantly non-displaced (67.6%), while Type 2 had a higher rate of secondary displacement (36.2%).
• Displaced Type 2 OCFs (2B, 2C) showed a significantly higher rate of tibial pseudoarthrosis (30.8%) compared to non-displaced Type 2A (4.8%).
• OCF types 1B, 2B, and 2C correlated with mechanical complications, with Type 2C fractures showing a markedly higher risk (OR 43.8) for tibial pseudoarthrosis.

Conclusions:

• Type 1 OCFs are stable, whereas Type 2 OCFs are unstable and prone to displacement.
• Intraoperative recognition of Type 2 OCFs was limited (57.4%), highlighting the need for careful postoperative radiographic assessment.
• The proposed OCF classification offers clinically relevant therapeutic guidance for CWHTO procedures.