A computer-implemented method comprising: displaying first and second images of first and second anatomical structure segments with a fixation device attached thereto, the fixation device for correction of a deformity of the first and the second anatomical structure segments , the first and the second images captured from different positions and orientations with respect to one another and having an angle between their image planes, the fixation device comprising rings , struts and a plurality of hinges ; receiving indications of first image hinge locations associated with the plurality of hinges in the first image ; determining, based at least in part on the indications of the first image hinge locations and the angle between the image planes of the first and second images , projected second image hinge locations associated with the plurality of hinges in the second image ; detecting hinge candidates (2111-2114) in the second image having shapes associated with the plurality of hinges ; identifying candidate second image hinge locations of the hinge candidates (2111-2114) in the second image ; calculating, based at least in part on the projected second image hinge locations and the candidate second image hinge locations, adjusted second image hinge locations associated with the plurality of hinges in the second image ; using the adjusted second image hinge locations to determine physical locations of the fixation device and the first and the second anatomical structure segments in three-dimensional space; and using the physical locations of the fixation device and the first and the second anatomical structure segments to determine manipulations to the fixation device for the correction of the deformity. displaying first and second images of first and second anatomical structure segments with a fixation device attached thereto, the fixation device for correction of a deformity of the first and the second anatomical structure segments , the first and the second images captured from different positions and orientations with respect to one another and having an angle between their image planes, the fixation device comprising rings , struts and a plurality of hinges ; receiving indications of first image hinge locations associated with the plurality of hinges in the first image ; determining, based at least in part on the indications of the first image hinge locations and the angle between the image planes of the first and second images , projected second image hinge locations associated with the plurality of hinges in the second image ; detecting hinge candidates (2111-2114) in the second image having shapes associated with the plurality of hinges ; identifying candidate second image hinge locations of the hinge candidates (2111-2114) in the second image ; calculating, based at least in part on the projected second image hinge locations and the candidate second image hinge locations, adjusted second image hinge locations associated with the plurality of hinges in the second image ; using the adjusted second image hinge locations to determine physical locations of the fixation device and the first and the second anatomical structure segments in three-dimensional space; and using the physical locations of the fixation device and the first and the second anatomical structure segments to determine manipulations to the fixation device for the correction of the deformity. <EOS>