Supramalleolar osteotomy (SMO) aims to correct extra-articular deformities of the distal lower leg. There are several indications, the most common being varus osteoarthritis of the ankle. The rationale in this indication is to modify talocrural stress and pressure distribution by reorienting the limb axis. Preoperative planning is essential to optimize functional outcome, limiting the risk of under- or over-correction. Several SMO procedures have been described, and are preferably performed at the deformity site or center of rotation and angulation (CORA). They aim to restore talocrural joint-line anatomy and correct talar tilt while conserving physiological hindfoot valgus. Techniques use K-wires as cut guides. 3D imaging and patient-specific instrumentation now play key roles in this surgery, which is difficult both to plan and to execute. The present study addresses the following questions: What are the indications and contraindications? What are the technical principles? What preoperative work-up is required for planning and execution? What are the technical particularities? And what contribution can new technologies make?

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