Ankle Malunion: A Systematic Case-Based Approach to Treatment and a Modified Classification
Abstract
A comprehensive review proposing the Patel-Dhillon Classification for ankle malunions. The system moves beyond simple fracture patterns to integrate Arthritis (Ar), Soft Tissue (ST), and Syndesmosis (Sy) status as critical prognostic modifiers.
The Patel-Dhillon Malunion Classification
Key Finding
"The proposed classification introduces four critical modifiers—Arthritis (Ar0-3), Previous Surgery (PS0-2), Soft Tissue (ST0-2), and Syndesmosis (Sy0-3)—to dictate the choice between reconstruction and salvage fusion."
Background: Traditional fracture classifications (Weber, Lauge-Hansen) fail to capture the complexity of chronic malunions, such as cartilage wear or syndesmotic widening. Surgeons lacked a unified language to describe the healed deformity, leading to inconsistent treatment planning and unpredictable outcomes.
Methods: The authors reviewed literature and institutional cases to develop a 3-Type system: Type I (Extra-articular), Type II (Intra-articular), and Type III (Complex/Pilon). They validated this via 6 illustrative cases, demonstrating a specific algorithm for osteotomy vs. fusion. A closed ring concept was applied to ensure multi-planar correction.
Results: The review establishes that if one malleolus is malreduced, the entire ring is compromised. For Type IIB (Bimalleolar) malunions, the authors describe a Technical Trick: performing posterior malleolus osteotomies anterior-to-posterior via the syndesmosis to ensure articular accuracy. Cases classified with high Ar or ST scores were diverted to arthrodesis rather than futile reconstruction.
Conclusion: All ankle malunions are different. Successful management requires a patho-anatomy driven approach. The Patel-Dhillon system forces the surgeon to evaluate the soft tissue envelope and joint status before cutting bone, preventing reconstruction failures in arthritic ankles.