Patent ID: 6567681
Filing Date: 2003-05-20
Classification: A61B

Abstract:
A method for determining, in three dimensions, where to position a fixating device in a hip fracture structure by pre-surgery analysis of at least one anteroposterior and one lateral digitized radiograph of said fracture, said method comprising:determining a construed femoral shaft axis out of said graphs from at least two midpoints on said shaft axis and drawing a line through said midpoints; determining a construed femoral neck axis from at least two midpoints on said neck axis and drawing a line through said midpoints; determining femoral neck angles (&agr;, &bgr;); determining a femoral head diameter out of said graphs by placing a circle over the perimeter of the femoral head; scaling and rotating said radiographs to a predefined size and position, using an angle between the femoral shaft and a Y-axis in said digitized radiographs, and said diameter of the femoral head; determining a femoral neck diameter out of said radiographs by drawing a line, perpendicular to the femoral neck axis, at the intersection of the femoral head sphere and the central femoral neck axis; determining the distance from said neck axis and the center of said femoral head perpendicular to the femoral neck axis, representing a remaining displacement of the hip fracture which is implicitly known from said head diameter; measuring the height of the medial cortex out of the anteroposterior graph; displaying said femoral neck angles (&agr;, &bgr;); displaying cross-sections of the femoral head and femoral neck with a predetermined degree of accuracy; rotating said cross-sections of the femoral head and femoral neck in order to determine a degree of derotation of the hip, imposed by the fracture; displaying the degree of hip rotation in said anteroposterior and lateral radiographs; and using said steps in order to determine a position, in three dimensions, for attachment of said fixating device.