Angulation osteotomy. A trigonometric analysis.

An analysis of an angular deformity of a long bone and a corrective osteotomy is presented to demonstrate that the effective length of a long bone is significantly shortened by an angular deformity, and that this amount of shortening can be easily calculated. A comparison of proximal versus distal sites for corrective osteotomy is made to demonstrate that a proximal site is generally advantageous. A method of precisely calculating the length of the base of the appropriate corrective wedge is defined. It is shown that a closing wedge osteotomy can result in a significant increase in the effective length of an angulated bone.