荷重時背底X線像における母趾基節骨回内評価法の考案

Abstract

The purpose of this study was to establish a new method for quantifying the amount of hallucal rotation on weight-bearing dorsoplantar radiographs and to explore the relationships between hallucal rotation and hallux valgus deformity. Methods: Anatomical features that enable assessment of the first proximal phalanx rotation were identified at the medial tubercle of its proximal articular surface. A Rotation Index (A/B x 100% : RI) was defined as the distance between the tip of the medial tubercle and the long axis (A), and the distance between the most medial and lateral edges of the proximal articular surface (B). The data were analyzed using a single regression analysis to investigate the relation between the value of the RI and the first proximal phalanx rotation (PRA). Using this single regression equation, the value of PRA was calculated from the RI on each dorsoplantar radiograph. Measurements were made of 78 feet of 48 female patients with symptomatic hallux valgus. As a control, 58 normal feet of 46 female subjects were also examined. A Pearson correlation coefficient was used to evaluate the relationship between the PRA and the hallux valgus angle (HVA). Results: A trend of decreasing RI with increasing pronation was observed, and the relationship was approximately linear. At a pronation of 10 degrees, an average change in the magnitude of the RI of 6.06% was observed. The mean value of the first proximal phalanx rotation angle was 8.5°in the control group and 27.7°in the hallux valgus group. We found that there was a high correlation between the amount of the first proximal phalanx rotation angle and the hallux valgus angle. The regression coefficient was 0.68. Conclusions: We conclude that the RI is reliable and usefu1 for accurately assessing the hallucal rotation under the weightbearing condition