Spinous process fixation devices and methods of use

Abstract

Orthopedic implant and methods of implantation for fixing adjacent bones. In one embodiment, the implant includes a locking mechanism that is adapted to be advanced by a locking instrument, wherein advancement of the locking mechanism in a first direction produces rotation of a first rigid abutment surface of the implant from a first orientation to a second orientation, and continued advancement of the locking mechanism produces advancement of the first rigid abutment surface towards a second rigid abutment surface of the implant. The continued advancement may also place a compressive load onto the implant sufficient to immobilize the implant relative to a first bony surface and a second bony surface.

What is claimed is: 
     
         1 . An orthopedic implant, comprising:
 an elongated body configured to extend along a longitudinal axis from a first proximal segment to a second distal segment, the elongated body comprising an internal bore configured to:
 accept a bone forming material therein; 
 occupy at least a portion of an internal volume of the elongated body; and 
 comprise at least one aperture configured to open onto an outer surface of the elongated body; 
   at least one rotational bone abutment member configured to attach to the second distal segment of the elongated body and configured to rotate from a first orientation to a second orientation relative to the elongated body;   at least one second bone abutment member configured to attach to the first proximal segment of the elongated body; and   a locking mechanism positioned at the first proximal segment of the elongated body, the locking mechanism configured to be advanced in a first direction to produce movement of the at least one second bone abutment member towards the at least one rotational bone abutment member;   wherein advancement of the locking mechanism in a second direction permits movement of the at least one second bone abutment member away from the at least one rotational bone abutment member.   
     
     
         2 . The orthopedic implant of  claim 1 , wherein the at least one rotational bone abutment member comprises at least one protrusion configured anchor onto bone. 
     
     
         3 . The orthopedic implant of  claim 2 , wherein the advancement of the locking mechanism in the first direction produces forceful advancement of the at least one protrusion onto a bony segment positioned between the at least one rotational bone abutment member and the second bone abutment member. 
     
     
         4 . The orthopedic implant of  claim 1 , wherein the at least one second bone abutment member comprises at least one protrusion configured to anchor onto bone. 
     
     
         5 . The orthopedic implant of  claim 4 , wherein the advancement of the locking mechanism in the first direction produces forceful advancement of the at least one protrusion onto a bony segment positioned between the at least one rotational bone abutment member and the second bone abutment member. 
     
     
         6 . The orthopedic implant of  claim 1 , further comprising a placement instrument configured to produce rotation of the rotational bone abutment member as the locking mechanism is advanced in the first direction. 
     
     
         7 . A method for the percutaneous decompression of a spinal canal, comprising:
 identifying on an imaging technique a spinal level to be implanted;   making an incision lateral to a vertebral midline;   advancing an orthopedic implant into an interspinous space of the spinal level to be decompressed, the orthopedic implant comprising an elongated body having an internal bore configured to accept a bone forming material therein, the internal bore occupying at least a portion of an internal volume of the elongated body and having an aperture opening onto an outer surface of the elongated body;   attaching at least one rotational bone abutment member to a distal segment of the elongated body of the orthopedic implant, the at least one rotational bone abutment member configured to rotate from a first orientation to a second orientation relative to the elongated body;   attaching at least one second bone abutment member to a proximal segment of the elongated member;   positioning a locking mechanism at the proximal segment of the elongated body; and   advancing the locking mechanism along a first direction to produce movement of the at least one second bone abutment member towards the at least one rotational bone abutment member and capturing a spinous process of each vertebral bone abutting the implanted inter-spinous space between the at least one rotational bone abutment member and the at least one second bone abutment member;   wherein advancement of the locking mechanism in a second direction opposing the first direction permits movement of the at least one second bone abutment member away from the at least one rotational bone abutment member.   
     
     
         8 . A method for treatment of a spinal segment, the spinal segment comprising first and second adjacent spinous processes, the method comprising:
 positioning a bone forming material within an internal bore of an orthopedic implant, the internal bore comprising at least 20% of an internal volume of the orthopedic implant and the bone forming material being configured to fuse with at least one of the first and second spinous processes;   advancing a first segment of the orthopedic implant from a first ipsliateral side to a second contralateral side of an interspinous ligament that interconnects the first and second spinous processes, the first segment comprising a segment of an elongated body and at least a first bone abutment member coupled to the elongated body;   rotating the first bone abutment member relative to the elongated body, the rotated first bone abutment member being at least partially positioned within the second contralateral side of the interspinous ligament;   causing a surface of a second bone abutment member to abut a side surface of at least one of the first and second spinous processes, the second bone abutment member being at least partially positioned within the first ipsilateral side of the interspinous ligament;   translating the second bone abutment surface towards the first bone abutment surface by advancement of a locking mechanism of the orthopedic implant; and   causing a forceful immobilization of at least one of the first and second spinous processes between the first and the second one abutment members.   
     
     
         9 . The method of  claim 8 , wherein the forceful immobilization of at least one the first and second spinous processes causes at least one protrusion of one of the first and second abutment surfaces to anchor onto bone. 
     
     
         10 . A kit for positioning an orthopedic implant within a subject, the kit comprising:
 an orthopedic implant comprising an elongated body extending along a longitudinal axis from a first proximal segment to a second distal segment, the elongated body comprising an external surface and an internal bore configured to occupy at least twenty percent of an internal volume of the elongated body, the internal bore further comprising an aperture configured to open onto the external surface;   at least one rotatable bone abutment member attached to the second distal segment of the elongated member and configured to rotate from a first orientation to a second orientation relative to the elongated body, the at least one rotatable bone abutment member comprising an external surface positioned along the external surface of the orthopedic implant; and   at least one elongated implant placement device configured to reversibly couple to the first proximal segment of the orthopedic implant, the at least one elongated implant placement device further configured to forcibly rotate the at least one rotatable bone abutment member from the first to the second orientation relative to the elongated body through an application of a force transmitted directly from the at least one elongated implant placement device to the external surface of the at least one rotatable bone abutment member.