Fig. 1

Evaluation method of pre- and postoperative Hounsfield unit (HU) values and cement penetration in computed tomography (CT) images. A Preoperative CT coronal section. (a) Sclerotic side and (b) nonsclerotic side. B Preoperative CT coronal section. Vertical and horizontal lines represent the tibial axis and the osteotomy line in operation, respectively. The shaded area is the estimated area of bone penetration by cement and was defined as the length of the base plate multiplied by 5 mm (the average HU values in the area are calculated by the imaging software). C Postoperative CT sagittal section. (1) Anterior edge of the keel, (2) center of the keel, and (3) extension of the posterior cortex. D Postoperative CT coronal section. The solid arrowhead indicates the cement penetration area of the sclerotic side (mm²), The open arrowhead indicates the cement penetration area of the nonsclerotic side (mm²). The single asterisk indicates the base of the sclerotic side (mm). The double asterisk indicates the base of the nonsclerotic side (mm). The single dagger presents the maximum penetration in the sclerotic side (mm). The double dagger refers to the maximum penetration in the nonsclerotic side (mm). Mean penetration: area/base (mm)