Fig. 1

Preoperative planning of cranial closing wedge osteotomy. The tibial plateau angle (TPA) was determined from the tibial plateau line and the perpendicular line of mechanical axis of the tibia. Point A was on the cranial cortex and 10% of the tibial long axial length distally from the insertion of the patellar ligament. After determining point A, the proximal osteotomy line, parallel to the tibial plateau line and passing through A, was established. Point B was defined as the intersection of the proximal osteotomy line and the caudal cortex. A distal osteotomy line passing through B was drawn to make the angle with line AB equal to the TPA. Point C was defined as the intersection of the distal osteotomy line and the cranial cortex