Fig. 2

Measurements of HKA angle, FFC, FTC and TCS. HKA: hip-knee-ankle; FFC: frontal femoral component angle; FTC: frontal tibial component angle; TCS: tibial component slope angle; A Preoperative HKA angle: the acute angle formed between the femoral mechanical axis (line a) and the tibial mechanical axis (line b). B Line c: postoperative femoral mechanical axis; line d: the line across the bottom of the femoral condyles; line e: the line across the bottom of the tibial plateau on the anteroposterior radiograph; line f: the postoperative tibial mechanical axis; FFC: the lateral angle between line c and line d; FTC: the medial angle between line e and line f; postoperative HKA angle: the acute angle between line c and line f. C Line g: the line across the bottom of the tibial plateau on the lateral radiograph; line h: the line connecting the center points of the tibial shaft 5 cm and 15 cm below the joint line; line i is perpendicular to line h; TCS: the acute angle between line i and line g