Collet Fixation System

Abstract

A bone fixation assembly which may include a bone fixation element, a collet and a flexible line. The bone fixation element may comprise a first and second passageway and at least the first passageway is configured to receive the collet. The flexible line passes through both passageways and is secured through the second passageway. The collet may be advanced into the first passageway causing the collet to circumferentially engage the flexible line fixing it in place. Instrumentation for securing the collet includes a collet driver, a counter torque instrument and a tensioner.

1 . A system comprising:
 a bone fixation element comprising a first end, a second end opposite the first end, and a first passageway extending between the first and second ends;   a first collet comprising a first portion, a second portion, and a central bore extending longitudinally between the first and second portions, wherein the first collet is movable along the first passageway between a first engaged position and a second position; and   a line comprising a first working portion and a second working portion connected to the first working portion, wherein the first working portion passes through the central bore of the first collet, wherein the second working portion is secured to the bone fixation element;   wherein, in the first engaged position, the first working portion of the line is held in a fixed position relative to the bone fixation element by the first collet, and the first collet is a first distance from the second end of the bone fixation element;   wherein, in the second position, the line slidably passes through the first collet, and the first collet is a second distance from the second end of the bone fixation element, wherein the second distance is greater than the first distance.   
     
     
         2 . The system of  claim 1 , wherein the first passageway comprises first threads and the first portion comprises second threads which are complementary to the first threads, wherein the first collet is secured within the first passageway by the complementary first and second threads. 
     
     
         3 . The system of  claim 1 , wherein the bone fixation element comprises a first snap interface and the first portion comprises a second snap interface which is complementary to the first snap interface, wherein the first collet is secured within the first passageway by the complementary first and second snap interfaces. 
     
     
         4 . The system of  claim 3 , wherein the bone fixation element comprises a plurality of successive snap interfaces, wherein the second snap interface engages each successive snap interface of the bone fixation element as the first collet slides farther within the first passageway. 
     
     
         5 . The system of  claim 1 , wherein the first portion comprises a first collet driver interface for attachment to a collet driver instrument. 
     
     
         6 . The system of  claim 1 , wherein the first end comprises a first counter torque interface for complementary fit with a second counter torque interface of a counter torque instrument. 
     
     
         7 . The system of  claim 1 , wherein the second portion comprises a plurality of protrusions within the central bore. 
     
     
         8 . The system of  claim 1 , wherein the line passes through the first passageway, wherein the first working portion, the first collet, and the first passageway are coaxial. 
     
     
         9 . The system of  claim 1 , wherein, in the first engaged position, the first collet is completely within the bone fixation element. 
     
     
         10 . The system of  claim 1 , wherein, in the first engaged position, the first collet circumferentially compresses around the first working portion with minimal deformation to the line, so as to hold the first working portion in a fixed position relative to the bone fixation element. 
     
     
         11 . The system of  claim 1 , wherein the bone fixation element comprises a second passageway extending between the first and second ends, wherein the second working portion is secured to the bone fixation element within the second passageway. 
     
     
         12 . The system of  claim 11 , comprising:
 a second collet like the first collet, wherein the second collet is movable along the second passageway between a third engaged position and a fourth position;   wherein, in the third engaged position, the second working portion of the line is held in a fixed position relative to the bone fixation element by the second collet, and the second collet is a third distance from the first end of the bone fixation element;   
       wherein, in the fourth position, the line slidably passes through the second collet, and the second collet is a fourth distance from the first end of the bone fixation element, wherein the fourth distance is greater than the third distance. 
     
     
         13 . A system comprising:
 a bone fixation element comprising a first end, a second end opposite the first end, and first and second passageways extending between the first and second ends;   a first collet comprising a first longitudinal central bore, wherein the first collet is movable along the first passageway between a first engaged position and a second position;   a second collet comprising a second longitudinal central bore, wherein the second collet is movable along the second passageway between a third engaged position and a fourth position; and   a line comprising a first working portion and a second working portion connected to the first working portion, wherein the first working portion passes through the first longitudinal central bore, wherein the second working portion passes through the second longitudinal central bore;   wherein, in the first engaged position, the first collet circumferentially engages the first working portion to fix the first working portion to the bone fixation element;   wherein, in the third engaged position, the second collet circumferentially engages the second working portion to fix the second working portion to the bone fixation element.   
     
     
         14 . The system of  claim 13 , wherein the first collet is secured within the first passageway by threads. 
     
     
         15 . The system of  claim 13 , wherein the first collet is secured within the first passageway by snap interfaces. 
     
     
         16 . The system of  claim 13 , wherein the first collet comprises a protrusion in the first longitudinal central bore. 
     
     
         17 . The system of  claim 13 , wherein the first and second collets each comprise a first collet driver interface for attachment to a collet driver instrument. 
     
     
         18 . The system of  claim 13 , wherein the bone fixation element comprises a first counter torque interface around a first opening for the first passageway, and a second counter torque interface around a second opening for the second passageway, wherein the first and second counter torque interfaces are for complementary fit with a third counter torque interface of a counter torque instrument. 
     
     
         19 . The system of  claim 13 , wherein, in the first engaged position, the first collet circumferentially compresses around the first working portion with minimal deformation to the line. 
     
     
         20 . A system comprising:
 a bone fixation element assembly comprising:
 a bone fixation element comprising a passageway, and a counter torque interface; and 
 a collet comprising a longitudinal central bore, and a collet driver interface, wherein the collet is movable along the passageway between a first engaged position and a second position; and 
   an instrument assembly comprising:
 a collet driver comprising a collet driver handle, a collet engagement interface in complementary engagement with the collet driver interface, and a collet driver shaft extending between the collet driver handle and the collet engagement interface, wherein rotation of the collet driver moves the collet along the passageway; and 
 a counter torque instrument comprising a counter torque handle comprising a notch, a key in complementary engagement with the counter torque interface, a counter torque shaft, and a counter torque bore extending longitudinally through the counter torque instrument, wherein the counter torque bore receives the collet driver shaft with clearance and the notch receives the collet driver handle with clearance; 
 wherein the counter torque instrument provides counter torque when the collet is moved along the passageway by the collet driver tool. 
   
     
     
         21 . The system of  claim 20 , wherein the counter torque interface comprises a plurality of circular slots equally spaced around an opening for the passageway. 
     
     
         22 . The system of  claim 21 , wherein the key comprises a plurality of prongs slidably engaged with the plurality of circular slots. 
     
     
         23 . The system of  claim 20 , wherein the collet driver interface comprises a shape selected from the group consisting of hexagon, square, and triangle. 
     
     
         24 . The system of  claim 20 , comprising:
 a line comprising a first working portion and a second working portion connected to the first working portion, wherein the first working portion passes through the longitudinal central bore, wherein the second working portion is secured to the bone fixation element.   
     
     
         25 . The system of  claim 24 , wherein, in the first engaged position, the first collet circumferentially compresses around the first working portion with minimal deformation to the line to fix the first working portion to the bone fixation element. 
     
     
         26 . The system of  claim 24 , wherein the collet driver comprises a collet driver bore, wherein the collet driver bore slidably receives the line.