Percutaneous compression and distraction system

[0001] The present application claims priority from Provisional Application No. 60/847,174, filed Sep. 25, 2006, the disclosure of which is hereby incorporated herein by reference.

[0002] 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.

[0003] 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.

[0004] 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.

[0005] 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.

[0006] 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.

[0007] 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.

[0008] 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.

[0009] 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.

[0010] 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.

[0029] FIGS. 1, 1A and 1B show a compression and distraction shaft A assembly 20. FIGS. 3, 3A and 3B show a compression and distraction shaft B assembly 22. A further assembly of the shaft A assembly 20 and shaft B assembly 22 forms a compression and distraction shaft assembly 24 seen in FIGS. 5, 5A, 6 and 6A.

[0030] Assembly 20 includes a shaft 26. FIG. 2 shows the details of construction of shaft 26. Shaft 26 has two long plates 28 attached to it in diametrically opposed location. One end of each of the plates 28 overhangs from the first end 30 of shaft 26. The overhanging portions are located opposite each other and have an arcuate shape at the very tip. The arcuate shape allows shaft 26 to lay over a rod that may be implanted on the vertebrae.

[0031] A tab 32 is attached in approximately middle of shaft 26. Tab 32 has a bore 34. Bore 34 has an hourglass shape along its central axis. A second end 36 of shaft 26 is on the opposing side from end 30. A fulcrum 38 is attached at second end 36. The means for attaching fulcrum 38 may be a bore 40 formed in shaft 26 and bore 42 formed in fulcrum 38 with a pin driven through bores 40 and 42 to connect fulcrum 38 to shaft 26.

[0032] Assembly 22 includes a shaft 44. FIGS. 4, 4A and 4B show the details of construction of shaft 44. Shaft 44 has a first end 46 and a second end 48. First end 46 is similar in construction to first end 30 of shaft 26. Shaft 44 has two long plates 50 attached to it in diametrically opposed location. One end of each of the plates 50 overhangs from the first end 46 of shaft 44. The overhanging portions are located opposite each other and have an arcuate shape at the very tip. The arcuate shape allows shaft 44 to lay over a rod that may be implanted on a vertebrae.

[0033] A tab 52 is attached in approximately middle of shaft 44. Tab 52 has a bore 54. Bore 54 has an hourglass shape along its central axis. A ball 56 is formed at second end 48. Ball 56 mates with fulcrum 38 to form a polyaxial fulcrum point. When shaft 26 and shaft 44 are assembled by inserting ball 56 in fulcrum 38 a 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.

[0034] FIGS. 7 and 7A show distraction pliers 60. Distraction pliers 60 have a first handle 62 and a second handle 64. First handle 62 has a tip end 66 and a ratchet end 68. First handle 62 has an elongate shape with a cylindrical tip 70 formed at tip end 66. At a distance below tip end 66 two tabs 72 and 74 extend from the body of first handle 62. Tabs 72 and 74 are parallel to each other and have a bore 75 formed through them. The handle end opposing tip end 66 also has two tabs 76 and 78 extend from the body of first handle 62. A bore 80 is formed through tabs 76 and 78. A screw hole 82 is formed at a distance from the ratchet end and above tabs 76 and 78. A leaf spring 84 is attached to first handle 62 by inserting a screw 86 in a hole in leaf spring 84 and threading screw 86 in screw hole 82. Leaf spring 82 has a far end that projects away from first handle 62. The far end has a notch 88 formed at its tip. A ratchet 89 is attached to ratchet end 68 of the first handle 62. The ratchet 89 has a bore 91 that aligns with bore 80 in tabs 76 and 78. A pin 93 is driven through bores 80 and 91 to attach ratchet 89 to first handle 62. Ratchet 89 has triangular projections formed on its surface.

[0035] Second handle 64 has a tip end 92 and a ratchet end 94. Second handle 64 has an elongate shape with a cylindrical tip 90 formed at tip end 92. At a distance below tip end 92 a tab 96 extends from the body of second handle 64. Tab 96 has a bore 98 formed through it. A leaf spring 100 is attached to second handle 64. Second handle 64 has two screw holes (not shown) formed above the ratchet end 94. Leaf spring 100 is attached to second handle 64 by threading two screws 102 and 104 via two holes in leaf spring 100 and into the screw holes in second handle 64. Leaf spring 100 has a far end that projects away from first handle 64. Leaf spring 100 has notch 108 formed at its tip. Notch 108 engages notch 88 thereby engaging leaf springs 84 and 100. When engaged, leaf springs 84 and 100 keep the distraction pliers biased in a closed position. A tooth 106 is formed at the tip of ratchet end 94. First handle 62 and second handle 64 are rotatably joined together by aligning bores 75 and 80 and inserting a screw 108 through them.

[0036] In use cylindrical tips 70 and 90 are inserted in hour glass shaped bores 34 and 54 and first handle 62 and second handle 64 pressed together. When the first handle 62 and the second handle 64 are pressed together, the cylindrical tip 70 and 90 are moved away from each other. This results in distraction of the vertebrae that are connected to the arcuate shaped end of the shaft A assembly 20 and shaft B assembly 22. The connection between the arcuate end of the shaft assemblies 20 and 22 and the vertebrae may be made in any known manner. For example, each of the shaft assemblies 20 and 22 may be connected to a cup of a pedicle screw mounted on the vertebra via a latch or a threaded connection. Once first handle 62 and second handle 64 are pressed to impart appropriate amount of distraction to the vertebrae they are locked in this position. Tooth 106 engages ratchet 89 to lock first handle 62 and second handle 64 in their pressed position, thereby holding the vertebrae in distracted position while the surgeon fixes a rod in the pedicle screws.

[0037] FIGS. 8 and 8A show compression pliers 110. Compression pliers 110 have a third handle 112 and a fourth handle 114. Third handle 112 has a tip end 116 and a ratchet end 118. A cylindrical tip 120 is formed at tip end 116. A hole 122 is formed in the body of third handle 112 below tip end 116. The end of third handle 112 opposing tip end 116 has two tabs 124 and 126. A bore 128 is formed through tabs 124 and 126. A screw hole 130 is formed in body of third handle 112 above tabs 124 and 126. A leaf spring 132 is attached to third handle 112 by inserting a screw 134 in a hole 136 formed in leaf spring 132 and threading the screw in the hole 130. Leaf spring 132 has a far end that projects away from third handle 112. The far end has a notch 138 formed at its tip. A ratchet 140 is attached to ratchet end 118 of the third handle 112. The ratchet 140 has a bore 142 that aligns with bore 128 in tabs 124 and 126. A pin 144 is driven through bores 128 and 142 to attach ratchet 140 to third handle 112. Ratchet 140 has triangular projections formed on its surface.

[0038] Fourth handle 114 has a tip end 146 and a ratchet end 148. Fourth handle 114 has a cylindrical tip 150 formed at tip end 146. At a distance below tip end 146 a bore 152 is formed in the body of third handle 114. A leaf spring 154 is attached to fourth handle 114. Fourth handle 114 has two screw holes (not shown) formed above the ratchet end 148. Leaf spring 154 is attached to fourth handle 114 by threading two screws 156 and 158 via two holes in leaf spring 154 and into the screw holes in fourth handle 114. Leaf spring 154 has a far end that projects away from fourth handle 114. Leaf spring 154 has notch 160 formed at its tip. Notch 160 engages notch 138 thereby engaging leaf springs 154 and 132. When engaged, leaf springs 132 and 154 keep the compression pliers biased in an open position. A tooth 162 is formed at the tip of ratchet end 148. Third handle 112 and fourth handle 114 are rotatably joined together by aligning bores 122 and 152 and inserting a screw 164 through them.

[0039] In use cylindrical tips 120 and 150 are inserted in hour glass shaped bores 34 and 54 and third handle 112 and fourth handle 114 pressed together. When the third handle 112 and fourth handle 114 are pressed together, cylindrical tips 120 and 150 are moved towards each other. This results in compression of the vertebrae that are connected to the arcuate shaped end of the shaft assembly 20 and shaft assembly 22. The connection between the arcuate end of the shaft assemblies 20 and 22 and the vertebrae may be made in any known manner. For example, each of the shaft assemblies 20 and 22 may be connected to a cup of a pedicle screw mounted on the vertebrae via a latch or a threaded connection. Once third handle 112 and fourth handle 114 are pressed to impart appropriate amount of compression to the vertebrae they are locked in this position. Tooth 162 engages ratchet 140 to lock third handle 112 and fourth handle 114 in their pressed position, thereby holding the vertebrae in compressed position while the surgeon fixes a rod in the pedicle screws.

[0040] 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.

[0041] Although the invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims.