Intramedullary fixation assembly and devices and methods for installing the same

Abstract

An intramedullary fixation assembly usable with different long bone types and a guide assembly for guiding deployment of the intramedullary fixation assembly. The intramedullary fixation assembly includes a fixation member that has ends and a curved body extending between the ends. The curved body of the fixation member has a radius of curvature configured to extend through the medullary canal regardless of the long bone anatomy. Fasteners fix the fixation member to the bone fragments and are guided by a guide assembly. The guide assembly includes a guide body defining openings configured to guide the fasteners through openings defined in the fixation member and into the bone fragments. A fixation end of the guide body includes a pair of opposing, converging surfaces that are configured to engage in a positive fit with an exposed end of the fixation member accessible through the side aperture in the first fragment.

1 . An intramedullary fixation assembly for repairing any of a plurality of human long bone types, each of the long bones defining a medullary canal fractured into at least a first and second adjacent bone fragments, the first bone fragment having a free end with an articular surface thereon and defining a side aperture, said side aperture positioned subjacent the articular surface and extending into the medullary canal, said intramedullary fixation assembly comprising: 
 at least a first and second fasteners, each of said fasteners having an elongate body with a head end and an opposite, bone-securing end; and    a fixation member having a first end, a second end and a body extending between the first and second ends,    said body defining a first fastener opening positioned proximate the first end and configured to allow passage of the first fastener therethrough and into the first bone fragment,    said body defining a second fastener opening positioned proximate the second end and configured to allow passage of the second fastener therethrough and into the second bone fragment, and    said body having a radius of curvature at least near the first end within a range of 1.5 to 5 inches to allow passage of the fixation member through the side aperture of the first bone fragment and into the medullary canal until the first end of the fixation member is positioned adjacent the side aperture and within a portion of the medullary canal defined within the first bone fragment, and the second end of the fixation member is positioned within a portion of the medullary canal defined within the second bone fragment, wherein the bone fragments are from any of the plurality of human long bone types.    
   
   
       2 . An intramedullary fixation assembly of  claim 1 , wherein the body continuously curves from its first end to its second end.  
   
   
       3 . An intramedullary fixation assembly of  claim 1 , wherein the radius of curvature is defined by a centerline extending from the first end to the second end.  
   
   
       4 . An intramedullary fixation assembly of  claim 3 , wherein the body includes a smoothly curving concave and convex sides configured to facilitate passage of the fixation member through the side aperture and into the medullary canal.  
   
   
       5 . An intramedullary fixation assembly of  claim 4 , wherein at least one of the first and second ends is tapered.  
   
   
       6 . An intramedullary fixation assembly of  claim 2 , wherein the radius of curvature is with a range of about 2.6 to 3.4 inches.  
   
   
       7 . An intramedullary fixation assembly of  claim 1 , wherein the fixation member includes a tilt.  
   
   
       8 . An intramedullary fixation assembly of  claim 1 , wherein at least one of the fasteners is a bi-cortical fastener having a threaded shaft with a wider diameter than the bone-securing end and separated from the bone-securing end by a non-threaded shaft portion.  
   
   
       9 . An intramedullary fixation assembly of  claim 1 , wherein the second end includes a tail portion having a relatively smaller diameter than the body.  
   
   
       10 . An intramedullary fixation assembly of  claim 9 , wherein the tail portion includes a pair of spaced arms defining a split configured to receive a fastener, and wherein insertion of the fastener forces the spaced arms apart.  
   
   
       11 . An intramedullary fixation assembly of  claim 1 , wherein at least one of the first and second ends has a taper and wherein the body has a continuous curvature extending between the ends.  
   
   
       12 . An intramedullary fixation assembly of  claim 1 , wherein the first end of the body includes additional fastener openings extending at divergent angles with respect to the first fastener openings.  
   
   
       13 . An intramedullary fixation assembly of  claim 12 , wherein the fastener openings at the first end of the body extend at an inclination angle matched to the articular surface.  
   
   
       14 . An intramedullary fixation assembly of  claim 13 , wherein the first end of the fixation member defines a surface configured to extend under and support the articular cartilage.  
   
   
       15 . An intramedullary fixation assembly of  claim 14 , wherein the body defines an exposed end surface accessible through the side aperture and having the first fastener opening extending therethrough.  
   
   
       16 . An intramedullary fixation assembly of  claim 15 , wherein the surface extending under the articular cartilage is at about a right angle to the exposed end surface.  
   
   
       17 . An intramedullary fixation assembly of  claim 16 , wherein the fixation member is configured to extend from a metaphysis of the long bone to the diaphysis of the longbone without extending into the epiphysis of the longbone, thereby avoiding damage to the articular cartilage.  
   
   
       18 . A bi-cortical bone fastener for use with a fixation member defining a fixation member opening having a diameter, said bone fastener comprising: 
 a first bone-securing shaft portion having threads configured for fixation into a first layer of bone, said first bone-securing shaft portion having a maximum diameter smaller than the fixation member opening diameter;    a mid-shaft portion adjacent the bone-securing shaft portion and configured to extend into the fixation member opening, said mid-shaft portion having a maximum diameter greater than the maximum diameter of the bone-securing shaft portion; and    a second bone-securing shaft portion adjacent the mid-shaft portion and opposite the first bone-securing shaft portion, said second bone-securing shaft portion having threads configured for fixation into a second layer of bone, said second bone-securing shaft portion having a maximum diameter greater than the diameter of the mid-shaft portion.