A patient with a malunited tibial fracture has a 20° anterior angulation deformity at the mid-shaft. Correction osteotomy should be performed at the apex of the deformity. The principle that correction at any level other than the apex creates a secondary translational deformity is described as:
- A Paley's CORA (Centre of Rotation of Angulation) principle ✓
- B Wolff's law
- C Ilizarov tension-stress principle
- D Davis law of soft tissue remodelling
Explanation
The CORA (Centre of Rotation of Angulation) principle, described by Paley, states that when correcting a bony deformity, the axis of correction rotation must pass through the CORA — the intersection point of the proximal and distal bone axis lines. Performing the osteotomy exactly at the CORA and correcting the angulation there eliminates deformity without creating a secondary translational malalignment (shift). If the osteotomy level is proximal or distal to the CORA, correction of angulation is achieved but a residual translation is introduced, requiring either a compensatory cut or acceptance of the shift. This principle is fundamental to all deformity correction planning including Ilizarov frame work.
Reference: Maheshwari Essential Orthopaedics, 6th ed.
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Written and medically reviewed by the StethoPrep medical team.