足と足首の臨床研究

抽象的な

Change of the X-ray Beam Angle may Influence Ankle Image of Weight-bearing Anteroposterior View: Trial to Evaluate Ankle Joint on Standing Whole-leg Radiograph

Ryuhei Katsui, Tadashi Fujii, Katsuya Ito, Akira Taniguchi and Yasuhito Tanaka

Upon evaluating the ankle joint structures by using standing whole-leg anteroposterior (AP) radiographs, the angle at which the X-ray beam is projected to the ankle joint, may distort the image. The accuracy and validity of the measurement of the ankle joint structure was investigated using weight-bearing AP radiographs obtained at several angles of X-ray beam projection for the clinical availability.

Three weight-bearing AP view radiographs of each limb were acquired upon projecting the X-ray beam cranially, and at 0°, 5°, and 10° to the ankle joint. The tibial anterior surface angle (TAS angle), tibial medial malleolus angle (TMM angle), and tibial bimalleolus angle (TBM angle) were measured on each weight-bearing AP view of the ankle joint. The measurements of the TAS, TMM, and TBM angles were then statistically compared.

The TAS angle did not change as the projected angle increased. No significant differences were observed between the groups. The TMM angle decreased gradually as the projected angle increased. A significant difference was observed between 0° and 10°. The TBM angle increased gradually as the projected angle increased. A significant difference was observed in the TBM angle between 0° and 5° as well as between 0° and 10°.

The TAS angle, which indicates varus/valgus deformity of the ankle joint, can assessed with the projected angle of 10°.