Ankle Malunion: A Systematic Case-Based Approach to Treatment and a Modified Classification

Ankle malunion remains a common issue despite advances in imaging and management protocols; it is a challenging problem that occurs after neglect or inadequate treatment. The consequences are pain, difficult gait, and eventual arthritis of the ankle joint, and demands aggressive management. The existing classification systems for ankle malunion are often too basic, and do not provide enough detail to guide specific treatment plans; our understanding of the complex anatomical issues and how they affect ankle mechanics has greatly improved with advanced imaging like CT and weight-bearing CT, and there is a need for a more comprehensive classification.

This paper reviews how our understanding of ankle malunion has evolved over time, looking at biomechanics, imaging techniques, and current classifications. A new comprehensive classification system called the Patel-Dhillon Classification was developed, and was used on individual cases to show how this system works in practice, detailing specific anatomical problems, surgical treatments, and outcomes. A step-by-step plan for managing ankle malunion has been suggested.

The proposed Patel-Dhillon classification divides malunions into three main types: Type I (Extra-articular), Type II (Intra-articular Malleolar/Plafond), and Type III (Complex with Articular Impaction/Deficiency). To provide a complete picture, we added four modifiers: Arthritis (Ar), Previous Surgery (PS), Soft Tissue Status (ST), and Syndesmotic Status (Sy). A systematic treatment algorithm, based on this classification is also presented, and its usefulness is demonstrated through six illustrative clinical cases.

A detailed, patho-anatomy driven classification system, like the one we propose, is essential for accurate diagnosis, planning personalized surgeries, predicting outcomes, and standardizing research in this complex area; this is because every ankle malunion has unique anatomical challenges.

The online version contains supplementary material available at 10.1007/s43465-025-01582-4.