Mobile spine stabilization device

Abstract

An orthopedic device is described for stabilizing the spinal column between first and second vertebral bodies. The device has first and second screws adapted for fixation to the first and second vertebral bodies, respectively. The device further includes an elongated ligament with a first end connected to the first screw and the second end operatively connected with the second screw. The ligament is made preferably of a nickel titanium alloy selected to have ductile inelastic properties at body temperature and is capable of continuous plastic deformation to allow relative constrained motion between the vertebral bodies. In a preferred embodiment the second pedicle screw includes a bearing for receiving the ligament in a slideably engageable relationship. The device further includes optional first and second dampening members surrounding the ligament for restraining the spinal column during flexion and extension. Other preferred devices and kits containing such devices are also described.

1 . An orthopedic device for stabilizing a first and second bone of the spinal column, the device comprising: 
 an elongated ligament having first and second ends, the ligament selected to exhibit inelastic characteristics at body temperature and further capable of continuous plastic deformation;    a first screw adapted to securely fasten the first end of the ligament to the first bone;    a second screw presenting a bearing for receiving the second end of the ligament and securing it in a mobily constrained fashion to the second bone, wherein    plastic deformation in the ligament allows relative constrained motion between the bones.    
     
     
         2 . The orthopedic device of  claim 1  wherein the implantable ligament is in the form of at least one wire, rod, tube, cable, band or plate.  
     
     
         3 . The orthopedic device of  claim 1  further comprising a dampening member surrounding the ligament and sandwiched between the first and second screw.  
     
     
         4 . The orthopedic device of  claim 1  wherein the second end of the ligament has an abutment.  
     
     
         5 . The orthopedic device of  claim 4  further comprising a dampening member oriented around the ligament and sandwiched between the second screw and the abutment.  
     
     
         6 . The orthopedic device of  claim 1  wherein the bearing further comprises a plastic material selected from polyethylene or polyetheretherketone.  
     
     
         7 . The orthopedic device of claim of  claim 1  wherein the ligament further comprises a nickel titanium alloy.  
     
     
         8 . The orthopedic device of  claim 7  wherein the ligament exhibits shape memory characteristics with a transition temperature above body temperature.  
     
     
         9 . An orthopedic device for stabilizing first and second vertebral bodies of the spinal column, the device comprising: 
 an elongated shape memory nickel titanium ligament having a transformation temperature above body temperature and exhibiting ductile characteristics during use, the ligament formed in the shape of a rod with first and second ends;    a first screw adapted to securely fasten the first end of the rod to the first vertebral body;    a second screw presenting a plastic linear bearing for receiving the second end of the rod and securing it in a slideably constrained fashion to the second vertebral body, wherein    ductile deformation in the ligament allows slideably constrained motion between the vertebral bodies.    
     
     
         10 . The orthopedic device of  claim 9  further comprising a dampening member surrounding the rod and sandwiched between the first and second screw.  
     
     
         11 . The orthopedic device of  claim 9  wherein the second end of the rod has an abutment.  
     
     
         12 . The orthopedic device of  claim 11  further comprising a dampening member oriented around the ligament and sandwiched between the second screw and the abutment.  
     
     
         13 . The orthopedic device of  claim 9  wherein the bearing further comprises a plastic material selected from polyethylene or polyetheretherketone.  
     
     
         14 . An orthopedic device for stabilizing first and second vertebral bodies of the spinal column, the device comprising: 
 an elongated shape memory nickel titanium ligament having a transformation temperature above body temperature and exhibiting ductile characteristics during use, the ligament formed in the shape of a rod with first and second end, the second end including an abutment;    a first screw adapted to securely fasten the first end of the rod to the first vertebral body;    a second screw presenting a plastic linear bearing for receiving the second end of the rod and securing it in a slideably constrained fashion to the second vertebral body,    a first dampening member surrounding the rod and sandwiched between the first screw and the second screw,    a second dampening member surrounding the rod and sandwiched between the second screw and the abutment, wherein    ductile deformation in the ligament allows slideably constrained motion between the vertebral bodies.