Paley and Tetsworth describe a stepwise radiographic planning method for correcting uniapical angular deformities of the tibia or femur that cause lower-limb mechanical axis deviation. The paper defines the Malalignment Test and establishes rules for determining whether osteotomy at or away from the deformity apex requires pure angulation versus combined angulation and translation.
When planning a corrective osteotomy for varus or valgus malalignment, first localize the apex using the Malalignment Test — if your osteotomy level will not be at the apex (e.g., metaphyseal cut for a juxtaarticular deformity), you must add a translational component or you will trade one deformity for another.
The magnitude of required translation scales directly with how far your osteotomy is from the true apex.
Paley and Tetsworth describe a stepwise radiographic planning method for correcting uniapical angular deformities of the tibia or femur that cause lower-limb mechanical axis deviation. The paper defines the Malalignment Test and establishes rules for determining whether osteotomy at or away from the deformity apex requires pure angulation versus combined angulation and translation.
When planning a corrective osteotomy for varus or valgus malalignment, first localize the apex using the Malalignment Test — if your osteotomy level will not be at the apex (e.g., metaphyseal cut for a juxtaarticular deformity), you must add a translational component or you will trade one deformity for another.
The magnitude of required translation scales directly with how far your osteotomy is from the true apex.