Gear mechanisms for fixation frame struts

Abstract

An adjustable length strut includes two joints, a threaded rod extending between the joints, and a tube adapted to receive the threaded rod. An actuation mechanism with gear teeth extending radially outward of the strut axis is rotatably fixed to the threaded rod. A protrusion may be coupled to an end of the threaded rod by a rotatable collar, with the protrusion extending through a slot in the tube to mark the length of the strut. A modular attachment member may be adapted to be couple to the first joint and include a worm gear adapted to engage gear teeth of the actuation mechanism. The modular attachment member may include a radiofrequency identity tag mechanism adapted to be read by a tag reader of a tool, the tool adapted to couple to the attachment member to rotate the worm gear to increase or decrease the effective length of the strut.

1 . An external fixation frame system, comprising:
 a first support ring extending along a first ring plane and having a plurality of first apertures extending through the first support ring in a direction orthogonal to the first ring plane;   a second support ring extending along a second ring plane and having a plurality of second apertures extending through the second support ring in a direction orthogonal to the second ring plane;   a plurality of telescopic struts each having a first joint proximate a first end of the strut and a second joint proximate a second end of the strut, wherein the plurality of struts can be lengthened to change a distance between the first joint and the second joint; and   a first offset plate having a first end adapted to couple to one of the first apertures of the first support ring, and a second end adapted to receive the first end of one of the telescopic struts, the second end of the first offset plate being positioned radially outward of the first support ring when the first end of the first offset plate is coupled to the first support ring,   wherein the first ends of the telescopic struts are adapted to couple to either (i) the first support ring via one of the first apertures directly, or (ii) the second end of the first offset plate when the first end of the first offset plate is coupled to the first support ring.   
     
     
         2 . The system of  claim 1 , further comprising a second offset plate having a first end adapted to couple to one of the second apertures of the second support ring, and a second end adapted to receive the second end of one of the telescopic struts, the second end of the second offset plate being positioned radially outward of the second support ring when the first end of the second offset plate is coupled to the second support ring. 
     
     
         3 . The system of  claim 1 , wherein the first offset plate and the second offset plate are substantially identical to one another. 
     
     
         4 . The system of  claim 1 , wherein the first end of the first offset plate includes a first extension sized and shaped to be received within one of the first apertures of the first support ring. 
     
     
         5 . The system of  claim 4 , wherein the first extension includes a first borehole extending therethrough for receiving a fastener therein. 
     
     
         6 . The system of  claim 1 , wherein the first end of the first offset plate includes a first aperture, and when the first aperture of the first offset plate is positioned coaxially with one of the first apertures of the first support ring, a fastener may pass through both the first aperture of the first offset plate and the one of the first apertures of the first support ring to secure the first offset plate to the first support ring. 
     
     
         7 . The system of  claim 6 , wherein the first end of the first offset plate includes a first extension sized and shaped to be received within one of the first apertures of the first support ring, the first extension being positioned adjacent to the first aperture of the first offset plate. 
     
     
         8 . The system of  claim 1 , wherein the second end of the first offset plate includes a receiving portion including a recess at least partially defined by a circumferential rim, the receiving portion sized and shaped to receive the first end of the strut. 
     
     
         9 . The system of  claim 8 , wherein the circumferential rim is substantially continuous so that the circumferential rim fully circumscribes the recess. 
     
     
         10 . The system of  claim 8 , wherein the circumferential rim is discontinuous so that the circumferential rim defines an opening, the circumferential rim less than fully circumscribing the recess. 
     
     
         11 . The system of  claim 10 , wherein when the first end of the strut is received within the recess of the second end of the first offset plate, a first aperture in the first end of the strut is aligned with the opening of the circumferential rim so that the first aperture in the first end of the strut is accessible while the first end of the strut is received within the recess. 
     
     
         12 . An offset plate for use in an external fixation system, the offset plate comprising:
 a first end adapted to couple to a support ring of the external fixation system, the first end having a cylindrical extension adapted to be received within an aperture of the support ring; and   a second end spaced from the first end, the second end including a circumferential rim defining a recess adapted to receive an end of a strut of the external fixation system therein, the recess being in communication with a borehole in the second end, the borehole in the second end adapted to align with a corresponding aperture of the strut when the strut is received within the recess.   
     
     
         13 . The offset plate of  claim 12 , wherein the cylindrical extensions includes a borehole extending therethrough for receiving a fastener therein. 
     
     
         14 . The offset plate of  claim 12 , wherein the first end of the offset plate includes a first aperture therein, and when the first aperture of the first offset plate is positioned coaxially with a corresponding aperture of the support ring, a fastener may pass through both the first aperture of the first end of the offset plate and the corresponding aperture of the support ring to secure the offset plate to the support ring. 
     
     
         15 . The offset plate of  claim 12 , wherein the circumferential rim is substantially continuous so that the circumferential rim fully circumscribes the recess. 
     
     
         16 . The system of  claim 12 , wherein the circumferential rim is discontinuous so that the circumferential rim defines an opening, the circumferential rim less than fully circumscribing the recess. 
     
     
         17 . A method of constructing an external fixation frame, the method comprising:
 coupling a first support ring to a second support ring, the first support ring extending along a first ring plane and having a plurality of first apertures extending through the first support ring in a direction orthogonal to the first ring plane, the second support ring extending along a second ring plane and having a plurality of second apertures extending through the second support ring in a direction orthogonal to the second ring plane, wherein coupling the first support ring the second support ring includes coupling a first end of a first telescopic strut to the first support ring via one of the first apertures in the first support ring, and coupling a second end of the first telescopic strut to the second support ring via one of the second apertures in the second support ring;   coupling a first end of a first offset plate to the first support ring via one of the first apertures of the first support ring;   coupling a first end of a second telescopic strut to a second end of the first offset plate so that the first end of the second telescopic strut is positioned radially outward of the first support ring; and   coupling a second end of the second telescopic strut to the second support ring.   
     
     
         18 . The method of  claim 17 , wherein coupling the second end of the second telescopic strut to the second support ring comprises directly coupling the second end of the second telescopic strut to the second support ring via one of the second apertures in the second support ring. 
     
     
         19 . The method of  claim 17 , further comprising coupling a first end of a second offset plate to the second support ring via one of the second apertures of the second support ring. 
     
     
         20 . The method of  claim 19 , wherein coupling the second end of the second telescopic strut to the second support ring comprises coupling the second end of the second telescopic strut to a second end of the second offset plate so that the second end of the second telescopic strut is positioned radially outward of the second support ring.