The 'center of rotation of angulation' (CORA) method is used for planning corrective osteotomy. If a corticotomy is performed AT the CORA level for a pure angular deformity, which of the following will result?

• A Correction of angulation without translation — mechanical axis is fully restored ✓
• B Correction of angulation with secondary translational deformity
• C Rotation of the distal segment around a point away from the mechanical axis
• D Creation of a new iatrogenic deformity at the osteotomy site

Explanation

The CORA (center of rotation of angulation) is the geometric intersection of the proximal and distal mechanical axes of the deformed bone. When a corrective osteotomy is performed precisely AT the CORA, pure rotational correction around this point restores both the angular deformity AND the mechanical axis simultaneously, without generating any secondary translational deformity. If the osteotomy is performed at a site REMOTE from the CORA, angular correction will introduce a new translation, requiring an additional translational correction to restore the mechanical axis.

Reference: Maheshwari Essential Orthopaedics, 6th ed.

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Written and medically reviewed by the StethoPrep medical team.