Patent ID: 7282052

Claim:
A unilateral fixator comprising: a strut assembly having a proximate end and a distal end; a first compound movable joint attached to the proximate end of the strut assembly having a first revolute joint with a first axis and a second revolute joint with a second axis; a second compound movable joint attached to the distal end of the strut assembly having a third revolute joint with a third axis and a fourth revolute joint with a fourth axis; and a bone fragment attachment apparatus attached to each of the first and second compound movable joints, wherein each of the revolute joints comprises a gear reduction mechanism, the gear reduction mechanism comprising: a left-hand helical spline; a right-hand helical spline; a thrust washer positioned between the right-hand helical spline and the left-hand helical spline; a helical spool, wherein the helical spool slides within the right-hand helical spline and the left hand helical spline and is rotationally engaged to the right-hand helical spline and the left hand helical spline; and a cap screw axially clamping together the left-hand helical spline, the right-hand helical spline, and the thrust washer and allowing for a fine adjustment of the reduction mechanism while the bone fragment attachment apparatus is engaged with a bone fragment.