Percutaneous compression and distraction system

The present invention provides a compression and distraction shaft assembly used to apply compression and distraction to bones including vertebrae. Shaft A assembly and shaft B assembly are attached together via a polyaxial fulcrum. The polyaxial fulcrum allows all rotational degrees of freedom between shaft A assembly and shaft B assembly. Such fulcrum, during compression and distraction, does not impart ancillary stresses or motion to vertebrae. A hour glass shaped bore for engaging pliers is formed in approximately middle of both the shaft A assembly and the shaft B assembly. A distraction pliers having cylindrical tips is used to apply distraction to vertebrae. Once handles are pressed to impart appropriate amount of distraction to the vertebrae they are locked in this position. A compression pliers having cylindrical tips is used to apply compression to vertebrae. Once handles are pressed to impart appropriate amount of compression to the vertebrae they are locked in this position.

BACKGROUND OF THE INVENTION

The present invention relates to a percutaneous compression and distraction system, more particularly to a system for percutaneous compression or distraction of vertebral bodies via pedicle screws.

BRIEF DESCRIPTION OF THE PRIOR ART

Various compression pliers and distraction devices are available to impart compression or distraction forces to bones. However, these devices fail to allow for all rotational degrees of freedom so as to not over constrain the desired compression or distraction motion and therefore fail to function appropriately when the trajectories of the compression and distraction shafts are non-coplanar. Therefore, there is a need for compression distraction system that provides a polyaxial fulcrum point that does not over constrain the motion and at the same time provides high mechanical advantage during compression and distraction of vertebral elements.

SUMMARY OF THE INVENTION

The present invention provides a compression and distraction shaft A assembly and a compression and distraction shaft B assembly. An assembly of the shaft A assembly and shaft B assembly forms a compression and distraction shaft assembly used to apply compression and distraction to bones including vertebrae. Shaft A assembly and shaft B assembly are attached together in use via a polyaxial fulcrum. The polyaxial fulcrum allows all rotational degrees of freedom between shaft A assembly and shaft B assembly. Such fulcrum, during compression and distraction, does not impart ancillary stresses or motion to vertebrae. An hour glass shaped bore for engaging pliers is formed in approximately middle of both the shaft A assembly and the shaft B assembly.

A distraction pliers having cylindrical tips is used to apply distraction to vertebrae. The tips of the distraction pliers are inserted in hour glass shaped bores and handles of the pliers pressed together to move the tips away from each other. This results in distraction of the vertebrae that are connected to the arcuate shaped end of the shaft A assembly and shaft B assembly. Once handles are pressed to impart appropriate amount of distraction to the vertebrae they are locked in this position.

A compression pliers having cylindrical tips is used to apply compression to vertebrae. The tips of the compression pliers are inserted in hour glass shaped bores and handles of the pliers pressed together to move the tips towards each other. This results in compression of the vertebrae that are connected to the arcuate shaped end of the shaft A assembly and shaft B assembly. Once handles are pressed to impart appropriate amount of compression to the vertebrae they are locked in this position.

An object of the preset invention is to provide a bone compression system having a first shaft and a second shaft. The first shaft has a first end and the second shaft has a second end. The first shaft is adapted to engage with an attachment to a first bone and the second shaft adapted to engage with an attachment to a second bone. The system includes compression pliers for compressing together the first shaft and the second shaft. The compression pliers engage the first shaft and the second shaft such that the first shaft and the second shaft can move in all directions independent of each other.

Another object of the invention is to provide a bone distraction system having a first shaft and a second shaft. The first shaft has a first end and the second shaft has a second end. The first end of the first shaft and the second end of the second shaft are adapted to mate with each other to provide a polyaxial fulcrum point about which the first shaft and the second shaft articulate. The system also includes distraction pliers for distracting the first shaft and the second shaft from each other. The distraction pliers engaging the first shaft and the second shaft such that the movement of the polyaxial fulcrum is not restricted by the distraction pliers.

Another object of the invention is to provide a bone compression and distraction system that includes all the components of the bone compression and bone distraction system described above.

Another object of the invention is to provide a method of compressing or distracting vertebral bodies. The method includes providing a first pedicle screw, a second pedicle screw, a compression and a distraction device. The compression and the distraction device each have a first shaft having a first end and a second end and a second shaft having a third end and a fourth end. The first end of the first shaft and the third end of the second shaft are mated with each other to provide a polyaxial fulcrum point about which the first shaft and the second shaft articulate. The second end of the first shaft and the fourth end of the second shaft are engaged with the first pedicle screw and the second pedicle screw respectively. Compression pliers or distraction pliers is engaged with the first shaft and the second shaft, and the vertebrae are compressed or distracted by operating the pliers.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1,1A and1B show a compression and distraction shaft A assembly20.FIGS. 3,3A and3B show a compression and distraction shaft B assembly22. A further assembly of the shaft A assembly20and shaft B assembly22forms a compression and distraction shaft assembly24seen inFIGS. 5,5A,6and6A.

Assembly20includes a shaft26.FIG. 2shows the details of construction of shaft26. Shaft26has two long plates28attached to it in diametrically opposed location. One end of each of the plates28overhangs from the first end30of shaft26. The overhanging portions are located opposite each other and have an arcuate shape at the very tip. The arcuate shape allows shaft26to lay over a rod that may be implanted on the vertebrae.

A tab32is attached in approximately middle of shaft26. Tab32has a bore34. Bore34has an hourglass shape along its central axis. A second end36of shaft26is on the opposing side from end30. A fulcrum38is attached at second end36. The means for attaching fulcrum38may be a bore40formed in shaft26and bore42formed in fulcrum38with a pin driven through bores40and42to connect fulcrum38to shaft26.

Assembly22includes a shaft44.FIGS. 4,4A and4B show the details of construction of shaft44. Shaft44has a first end46and a second end48. First end46is similar in construction to first end30of shaft26. Shaft44has two long plates50attached to it in diametrically opposed location. One end of each of the plates50overhangs from the first end46of shaft44. The overhanging portions are located opposite each other and have an arcuate shape at the very tip. The arcuate shape allows shaft44to lay over a rod that may be implanted on a vertebrae.

A tab52is attached in approximately middle of shaft44. Tab52has a bore54. Bore54has an hourglass shape along its central axis. A ball56is formed at second end48. Ball56mates with fulcrum38to form a polyaxial fulcrum point. When shaft26and shaft44are assembled by inserting ball56in fulcrum38a poly axial fulcrum that allows all rotational degrees of freedom is formed. Such fulcrum, during compression and distraction, does not impart ancillary stresses or motion to vertebrae.

FIGS. 7 and 7Ashow distraction pliers60. Distraction pliers60have a first handle62and a second handle64. First handle62has a tip end66and a ratchet end68. First handle62has an elongate shape with a cylindrical tip70formed at tip end66. At a distance below tip end66two tabs72and74extend from the body of first handle62. Tabs72and74are parallel to each other and have a bore75formed through them. The handle end opposing tip end66also has two tabs76and78extend from the body of first handle62. A bore80is formed through tabs76and78. A screw hole82is formed at a distance from the ratchet end and above tabs76and78. A leaf spring84is attached to first handle62by inserting a screw86in a hole in leaf spring84and threading screw86in screw hole82. Leaf spring82has a far end that projects away from first handle62. The far end has a notch88formed at its tip. A ratchet89is attached to ratchet end68of the first handle62. The ratchet89has a bore91that aligns with bore80in tabs76and78. A pin93is driven through bores80and91to attach ratchet89to first handle62. Ratchet89has triangular projections formed on its surface.

Second handle64has a tip end92and a ratchet end94. Second handle64has an elongate shape with a cylindrical tip90formed at tip end92. At a distance below tip end92a tab96extends from the body of second handle64. Tab96has a bore98formed through it. A leaf spring100is attached to second handle64. Second handle64has two screw holes (not shown) formed above the ratchet end94. Leaf spring100is attached to second handle64by threading two screws102and104via two holes in leaf spring100and into the screw holes in second handle64. Leaf spring100has a far end that projects away from first handle64. Leaf spring100has notch108formed at its tip. Notch108engages notch88thereby engaging leaf springs84and100. When engaged, leaf springs84and100keep the distraction pliers biased in a closed position. A tooth106is formed at the tip of ratchet end94. First handle62and second handle64are rotatably joined together by aligning bores75and80and inserting a screw108through them.

In use cylindrical tips70and90are inserted in hour glass shaped bores34and54and first handle62and second handle64pressed together. When the first handle62and the second handle64are pressed together, the cylindrical tip70and90are moved away from each other. This results in distraction of the vertebrae that are connected to the arcuate shaped end of the shaft A assembly20and shaft B assembly22. The connection between the arcuate end of the shaft assemblies20and22and the vertebrae may be made in any known manner. For example, each of the shaft assemblies20and22may be connected to a cup of a pedicle screw mounted on the vertebra via a latch or a threaded connection. Once first handle62and second handle64are pressed to impart appropriate amount of distraction to the vertebrae they are locked in this position. Tooth106engages ratchet89to lock first handle62and second handle64in their pressed position, thereby holding the vertebrae in distracted position while the surgeon fixes a rod in the pedicle screws.

FIGS. 8 and 8Ashow compression pliers110. Compression pliers110have a third handle112and a fourth handle114. Third handle112has a tip end116and a ratchet end118. A cylindrical tip120is formed at tip end116. A hole122is formed in the body of third handle112below tip end116. The end of third handle112opposing tip end116has two tabs124and126. A bore128is formed through tabs124and126. A screw hole130is formed in body of third handle112above tabs124and126. A leaf spring132is attached to third handle112by inserting a screw134in a hole136formed in leaf spring132and threading the screw in the hole130. Leaf spring132has a far end that projects away from third handle112. The far end has a notch138formed at its tip. A ratchet140is attached to ratchet end118of the third handle112. The ratchet140has a bore142that aligns with bore128in tabs124and126. A pin144is driven through bores128and142to attach ratchet140to third handle112. Ratchet140has triangular projections formed on its surface.

Fourth handle114has a tip end146and a ratchet end148. Fourth handle114has a cylindrical tip150formed at tip end146. At a distance below tip end146a bore152is formed in the body of third handle114. A leaf spring154is attached to fourth handle114. Fourth handle114has two screw holes (not shown) formed above the ratchet end148. Leaf spring154is attached to fourth handle114by threading two screws156and158via two holes in leaf spring154and into the screw holes in fourth handle114. Leaf spring154has a far end that projects away from fourth handle114. Leaf spring154has notch160formed at its tip. Notch160engages notch138thereby engaging leaf springs154and132. When engaged, leaf springs132and154keep the compression pliers biased in an open position. A tooth162is formed at the tip of ratchet end148. Third handle112and fourth handle114are rotatably joined together by aligning bores122and152and inserting a screw164through them.

In use cylindrical tips120and150are inserted in hour glass shaped bores34and54and third handle112and fourth handle114pressed together. When the third handle112and fourth handle114are pressed together, cylindrical tips120and150are moved towards each other. This results in compression of the vertebrae that are connected to the arcuate shaped end of the shaft assembly20and shaft assembly22. The connection between the arcuate end of the shaft assemblies20and22and the vertebrae may be made in any known manner. For example, each of the shaft assemblies20and22may be connected to a cup of a pedicle screw mounted on the vertebrae via a latch or a threaded connection. Once third handle112and fourth handle114are pressed to impart appropriate amount of compression to the vertebrae they are locked in this position. Tooth162engages ratchet140to lock third handle112and fourth handle114in their pressed position, thereby holding the vertebrae in compressed position while the surgeon fixes a rod in the pedicle screws.

The compression distraction pliers may also be used with compression distraction shafts that are not attached to each other. These shafts can be attached rigidly to the tips of the compression or distraction pliers and impart compression or distraction to the bones. The compression distraction system may also be used with minimally invasive surgery as described, for example, in commonly assigned patent application filed on even date and entitled “ROD CONTOURING APPARATUS AND METHOD FOR PERCUTANEOUS PEDICLE SCREW EXTENSION.” This patent application entitled “Rod Contouring Apparatus And Method For Percutaneous Pedicle Screw Extension,” application Ser. No. 11/526,785, is incorporated herein by reference in its entirety.