Static Compression Device

Abstract

A Static Compression Device (SC device) for active, measurable compression of a spinal fusion graft is disclosed. The SC device attaches to adjacent vertebral bodies or other pieces of bone and works with a compression tool to apply compressive force to adjacent vertebral bodies or pieces of bone to assist fusion. Once compressed, the SC device locks to maintain the compression applied at surgery, while preventing further compression after surgery. In one embodiment, the compression device applies a desired amount of force to allow the surgeon more control over the force applied to a cervical, thoracic or lumbar implant than previously available. The SC device may compresses multiple adjacent vertebrae across adjacent bone graft(s) to facilitate fusion of these vertebrae to treat pain from damaged disks between vertebrae that may on the spinal cord and nerve roots. SC device may also apply compression across fractures to facilitate union.

We claim: 
     
         1 . A device for compressing two or more adjacent bones or bone fragments, comprising:
 a male plate having at least a first protrusion extending away from the male plate along a longitudinal axis in a first direction, the male plate having holes adaptable for insertion of screws to attach the plate to a first one of the two or more adjacent bones;   a first female plate having a cavity substantially parallel to the longitudinal axis, the cavity being adapted to receive the first protrusion when the male plate is aligned with the first female plate, and the first female plate has holes for attachment to a second one of the two or more adjacent bones; and   a first locking mechanism comprising a plurality of shapes selected from the group consisting of ridges and valleys formed on the protrusion of the male plate, and a mating plurality of shapes selected from the group consisting of ridges and valleys formed on a surface of the cavity of the first female plate, and a screw adapted to engage threads of the protrusion of the male plate and hold the surface of the cavity of the first female plate to the protrusion of the male plate thereby engaging a plurality of the ridges and valleys;   wherein at least two plates of the device have a feature for coupling a compressing tool to the plate.   
     
     
         2 . A device of  claim 1  wherein the male plate is engaged with the first female plate, where the screw is adapted to slide in a slot of the female plate, and wherein at least one pin of the protrusion of the male plate extends into a slot of the female plate and adapted to retain the protrusion of the male plate in engagement with the cavity of the female plate. 
     
     
         3 . A device of  claim 1  wherein the male plate is a double-male plate having a second protrusion extending away from the male plate in a second direction along the longitudinal axis, and further comprising:
 a second female plate having a cavity substantially parallel to the longitudinal axis, the cavity being adapted to receive the at least one protrusion when the male plate is aligned with the female plate, and the second female plate has holes for attachment to a third one of the two or more adjacent bones; and 
 a second locking mechanism comprising a plurality of shapes selected from the group consisting of ridges and valleys formed on the protrusion of the male plate, and a mating plurality of shapes selected from the group consisting of ridges and valleys formed on a surface of the cavity of the second female plate, and a second screw adapted to engage threads of the protrusion of the male plate and hold the surface of the cavity of the second female plate to the protrusion of the male plate thereby engaging a plurality of the ridges and valleys. 
 
     
     
         4 . A device of  claim 1  wherein the male plate is engaged with the first and second female plates, where the first screw is adapted to slide in a slot of the first female plate, and the second screw is adapted to slide in a slot of the second female plate, wherein at least one pin of the first protrusion of the male plate extends into a slot of the first female plate and is adapted to retain the protrusion of the male plate in engagement with the cavity of the first female plate, and wherein at least one pin of each of the second protrusion of the male plate extends into a slot of the second female plate and is adapted to retain the second 
     
     
         5 . A device of  claim 4  wherein the second female plate is a daisy-chain plate having a protrusion aligned with the longitudinal axis and configured to engage within a cavity of a third female plate; the device further comprising:
 a third locking mechanism comprising a plurality of shapes selected from the group consisting of ridges and valleys formed on the protrusion of the second female plate, and a mating plurality of shapes selected from the group consisting of ridges and valleys formed on a surface of the cavity of the third female plate, and a screw adapted to engage threads of the protrusion of the male plate and hold the surface of the cavity of the first female plate to the protrusion of the male plate thereby engaging a plurality of the ridges and valleys. 
 
     
     
         6 . A device of  claim 1  wherein the male plate is a daisy-chain plate having a second cavity extending away from the male plate in a second direction along the longitudinal axis, and further comprising:
 a second male plate having a protrusion substantially parallel to the longitudinal axis, the second cavity being adapted to receive the protrusion of the second male plate when the daisy-chain plate is aligned with the second male plate, and the second male plate has holes for attachment to a third one of the two or more adjacent bones; and 
 a second locking mechanism comprising a plurality of shapes selected from the group consisting of ridges and valleys formed on the protrusion of the second male plate, and a mating plurality of shapes selected from the group consisting of ridges and valleys formed on a surface of the cavity of the daisy-chain plate, and a second screw adapted to engage threads of the protrusion of the daisy-chain plate and hold the surface of the cavity of the daisy-chain plate to the protrusion of the second male plate thereby engaging a plurality of the ridges and valleys. 
 
     
     
         7 . A device of  claim 6  wherein the male plate is engaged with the first female plate, where the screw is adapted to slide in a slot of the female plate, and wherein at least one pin of the protrusion of the male plate extends into a slot of the female plate and adapted to retain the protrusion of the male plate in engagement with the cavity of the female plate. 
     
     
         8 . A device of  claim 6  wherein the first male plate and first female plate have features permitting attachment of a compression device configured to apply compressive force sliding the protrusion of the first male plate into the cavity of the first female plate. 
     
     
         9 . A method of fusing bones comprising:
 Providing a fixation device further comprising:
 a male plate having at least a first protrusion extending away from the male plate along a longitudinal axis in a first direction, the male plate having holes adaptable for insertion of screws to attach the plate to a first bone portion; 
 a first female plate having a cavity substantially parallel to the longitudinal axis, the cavity being adapted to receive the first protrusion when the male plate is aligned with the first female plate, and the first female plate has holes for attachment to a second one of the two or more adjacent bones; and 
 a first locking mechanism comprising a plurality of shapes selected from the group consisting of ridges and valleys formed on the protrusion of the male plate, and a mating plurality of shapes selected from the group consisting of ridges and valleys formed on a surface of the cavity of the first female plate, and a screw adapted to engage threads of the protrusion of the male plate and hold the surface of the cavity of the first female plate to the protrusion of the male plate thereby engaging a plurality of the ridges and valleys; 
 wherein at least two plates selected from male and female plates of the device have a feature adapted for attachment of a compressing tool; 
 attaching each plate of the device to bone; 
 attaching a compressing tool to the device; 
 applying force to the device with a compressing tool, the force acting to slide the protrusion of the male plate into a compressed position in the cavity of the female plate and apply compressive force to bone; and 
 tightening the screw of the first locking mechanism to retain the male and female plate in compressed position.