Abstract
The purpose of this study was to evaluate the inter- and intra-observer reliability of mechanical alignment of the lower extremity with digital computed radiographs of frontal view of the whole leg using a new computer-assisted method. Three examiners measured the alignment of the whole leg in 105 legs of 73 subjects who had osteoarthritis of the knee with a Kellgren-Lawrence grade of >1. A line of mechanical axis from the center of the femoral head to the center of the ankle was drawn, and the alignment of the leg was assessed by the measurement of the perpendicular distance from the middle of the proximal tibial condyles to the mechanical axis (Fuji film OP-A), then calculated as a percentage of its ratio.
The inter-observer mean difference was 2.9% (SD; 2.7), the intra-observer mean difference was 2.1% (SD; 2.2). The inter-observer mean intraclass correlation coefficient (ICC) was 0.96, the intra-observer mean ICC was 0.99. Our computer-assisted method was simple, easy, rapid, and should be considered as an alternate method for the measurement of the alignment in whole leg.
