BI-DIRECTIONAL FIXATING TRANSVERTEBRAL BODY SCREWS, ZERO-PROFILE HORIZONTAL INTERVERTEBRAL MINIPLATES, TOTAL INTERVERTEBRAL BODY FUSION DEVICES, AND POSTERIOR MOTION-CALIBRATING INTERARTICULATING JOINT STAPLING DEVICE FOR SPINAL FUSION

Abstract

An apparatus and method for joining members together using a self-drilling screw apparatus or stapling apparatus are disclosed. The screw apparatus includes a worm drive screw, a spur gear and superior and inferior screws which turn simultaneously in a bi-directional manner. A rotating mechanism drives the first and second screw members in opposite directions and causes the screw members to embed themselves in the members to be joined. The screw apparatus can be used to join members such as bones, portions of the spinal column, vertebral bodies, wood, building materials, metals, masonry, or plastics. A device employing two screws (two-in-one) can be combined with a capping horizontal mini-plate. A device employing three screws can be combined in enclosures (three-in-one). The stapling apparatus includes grip handles, transmission linkages, a drive rod a fulcrum and a cylinder. The staple has superior and inferior segments with serrated interfaces, a teethed unidirectional locking mechanism and four facet piercing elements. The staples can be also be used to join members such as bones, portions of the spinal column, or vertebral bodies.

Claims

1. A self-drilling screw apparatus, which comprises: a gear box; a first screw member having a tapered end and a threaded body disposed within the gear box; a second screw member having a tapered end and a threaded body disposed within the gear box, the second screw member being axially offset from the first screw member; and a drive mechanism, including a gear disposed between the first and second screw members, for driving the first and second screw members from the gear box.

2. An apparatus according to claim 1 wherein the gear box includes an aperture which provides access to a wormed drive screw.

3. An apparatus according to claim 1 wherein the drive mechanism wherein the gear is a spur gear which is driven by a wormed drive screw and which rotates the first and second screw members.

4. An apparatus according to claim 3 wherein the wormed drive screw includes an accessible head that is rotated in order to drive the first and second screw members from the gear box.

5. An apparatus according to claim 3 wherein the first and second screw members include internal threading and spindles.

6. An apparatus according to claim 3 wherein the wormed drive screw includes a spindle.

7. An apparatus according to claim 4 wherein the accessible head is rotated by a screw driver

8. An apparatus according to claim 1 further including: at least a second gear box; a third screw member having a tapered end and a threaded body disposed within the second gear box; a fourth screw member having a tapered end and a threaded body disposed within the second gear box, the fourth screw member being axially offset from the third screw member; and a second drive mechanism, including a gear disposed between the third and fourth screw members, for driving the third and fourth screw members from the second gear box.

9. An apparatus according to claim 8 which further includes a plate for joining the first and second gear boxes together.

10. An apparatus according to claim 9 wherein the plate includes screw caps.

11. An apparatus according to claim 8 further including: at least a third gear box; a fifth screw member having a tapered end and a threaded body disposed within the third gear box; a sixth screw member having a tapered end and a threaded body disposed within the third gear box, the sixth screw member being axially offset from the fifth screw member; and a third drive mechanism, including a gear disposed between the fifth and sixth screw members for driving the fifth and sixth screw members from the third gear box.

12. An apparatus according to claim 11 wherein the gear boxes are aligned in a predetermined pattern and a first enclosure is disposed above the gear boxes and a second enclosure is disposed below the gear boxes.

13. An apparatus according to claim 12 wherein the gear boxes are aligned in a triangular pattern.

14. An apparatus according to claim 13 wherein the first and second enclosures include slots for bone fusion material.

15. A staple for joining facets, comprising: a first rotatable segment having a plurality of bone piercing elements, disposed on serrated surfaces; a second rotatable segment having a plurality of bone piercing elements, disposed on serrated surfaces; and a unidirectional locking mechanism coupled to the first and second rotatable segment, that permits the first and second rotatable segments to rotate about a pivot point, said unidirectional locking mechanism including a plurality of teeth.

16. A staple according to claim 15 wherein the unidirectional locking mechanism includes a lock washer and the teeth include right angled surfaces.

17. A staple according to claim 16 wherein the bone piercing elements have include a pointed end and a base which is disposed on the serrated surfaces.

18. A stapling apparatus for a staple having rotatable segments, which comprises: a cylinder; a drive rod disposed within the cylinder, said drive rod having first and second ends; a pair of grip handles disposed at a first end of the cylinder; a linkage coupling the grip handles to the first end of the drive rod; and a coupling mechanism disposed at the second end of the drive rod; wherein when the grip handles are forced together, the linkage imparts motion to the drive rod and the coupling mechanism.

19. A stapling apparatus according to claim 18 which further includes a fulcrum that is disposed at the first end of the cylinder and coupled to the linkage.

20. A stapling apparatus according to claim 19 wherein the cylinder further includes a second end having a chamfered slot through which the coupling mechanism of the drive rod moves with respect to the cylinder.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] FIG. 1A illustrates an isometric view of the universal bidirectional screw (UBS) alternatively referred to as the bi-directional fixating transvertebral screw (BDFT).

[0018] FIG. 1B illustrates the lateral view of the UBS (BDFT) with rostral and caudal screws partially extended.

[0019] FIG. 1C illustrates the lateral view of the UBS (BDFT) with the screws withdrawn.

[0020] FIG. 2 illustrates a front view of the UBS (BDFT) without the gear box and cover.

[0021] FIGS. 3A and 3B illustrate perspective, and exploded perspective views, respectively, of the UBS (BDFT) without gear box and cover, with the screws fully extended.

[0022] FIG. 4 illustrates a perspective view of the UBS (BDFT) without the gear box and cover, with screws partially extended.

[0023] FIG. 5A illustrates a perspective view of a single insertion screw of the BDFT.

[0024] FIG. 5B illustrates a perspective cross-sectional view of a BDFT insertion screw.

[0025] FIG. 5C illustrates a perspective view of the spindle.

[0026] FIG. 6A illustrates an exploded view of the two-in-one design consisting of two BDFT screws and a horizontal mini-plate.

[0027] FIG. 6B illustrates the two-in-one design with the horizontal mini-plate secured and the screws extended.

[0028] FIG. 6C illustrates the two-in-one design, and its position with respect to the vertebral body.

[0029] FIG. 7A illustrates an exploded view of the three-in-one system (IBFD) which consists of three BDFT screws in an enclosure system.

[0030] FIG. 7B illustrates the three-in-one system (IBFD) with screws extended.

[0031] FIG. 7C illustrates the IBFD with an accompanying screw driver.

[0032] FIGS. 8A and 8B illustrate perspective, and cross-sectional views of the interarticular joint stapling device with staple, respectively.

[0033] FIGS. 9A and 9B illustrate perspective and exploded views of the staple, respectively.

[0034] FIG. 10 illustrates a perspective view of the staple gun engaging the facet joint.

[0035] FIG. 11 illustrates the remote action mechanism of the staple gun.

[0036] FIGS. 12A-E illustrate the different components of the staple gun. FIG. 12A illustrates the drive rod. FIG. 12B illustrates the fulcrum cylinder connector.

[0037] FIG. 12C illustrates the grip handle. FIG. 12D illustrates the cylinder. FIG. 12E illustrates the cylinder with the drive rod.

[0038] FIG. 13 illustrates the drive and insertion mechanism of the staple.

DETAILED DESCRIPTION OF THE INVENTION

1. The Medical Device

[0039] Referring to FIGS. 1A-5C the above described problem can be solved in the cervical, thoracic and lumbar spine by insertion into the denuded intervertebral disc space a bi-directional fixating transvertebral (BDFT) screw or (UBS) screws 100.

[0040] FIGS. 1A through 1C illustrate three-dimensional views of the UBS/BDFT screw 100. All its inner components are in the gear box casing 101. The internal mechanisms are illustrated in FIGS. 2-5C. FIG. 1A illustrates the isometric view of the UBS 100 showing the outer gear box 101 containing the external mechanism, with superior screw 102 and inferior screw 103 extended. There are serrations 104 on the superior and inferior surfaces of the box 101 intended to integrate with the surface of the superior and inferior vertebral body surfaces. The gear box 101 which is made either of PEEK (polyethylene-ketol) or titanium acts as a column preventing subsidence of the disc space. Also seen are the surface of the worm drive screw 105, and the horizontal mini-plate screw insert 106 for capping the horizontal mini-plate to the gear box's 101 surface (FIGS. 1A-C and 6A-C).

[0041] FIGS. 1-4 illustrate the inner components of the BDFT/UBS 100 without the enclosing gear box 101. The inner components include a single wormed drive screw 105, a drive spindle 201, a spur gear 202, superior screw 102 and inferior screw 103 with superior and inferior screw spindles 205, 206 (FIGS. 1-4). The mechanism of operation is thus: The wormed drive screw 105 is rotated clockwise. This rotation in turn rotates the spur gear 202. The spur gear 202 interdigitates with the superior screw 102 on one side and the inferior screw 103 on the other side. Rotation of the spur gear 202 leads to simultaneous rotation of the superior and inferior screws 102, 103 in equal and opposite directions. The spindles in the wormed drive screw 105 and the superior and inferior screws 102, 103 maintain the axis of screw orientation. The screws 102, 103 are self drilling and hence there is no need for bony preparation.

[0042] FIGS. 5A and 5B illustrate in perspective and cross-sectional views the detailed elements of the superior and inferior screws 102, 103. These figures illustrate the external threading 501, the internal threading 502, the spindle socket and the spur gear teeth 503 which interdigitate with the spur gear 202. The screws 102, 103 are self drilling as noted.

[0043] FIG. 5C illustrates the details of the spindle including its base 505, its rod 506 and its threaded segment 507.

[0044] FIGS. 6A-6C illustrate the two-in-one design concept. This design concept includes two UBS/BDFT screws 100a, 100b which are placed in the left and right portions of the intervertebral disc space, which are then capped by a horizontal mini-plate 600. Note how the mini-plate has four perforations. There are two perforations 601, 602, one on each side to allow entry of the wormed screw drive into the gear box. There are an additional two perforations 603, 604, one on each side, to secure the plate to the two UBS boxes 100a, 100b with plate screw caps 605, 606. FIG. 6C demonstrates the position of the two-in-one system with respect to the vertebral body 610. In between the two BDFT/UBS screws 100a, 100b, bone fusion material is inserted. The horizontal mini-plate 600 prevents the bone from growing into the nerves above it. With this system it is also possible to place a third screw inferior and in the middle of the two other UBS screws 100a, 100b thereby providing additional screw intervertebaral fixation.

[0045] FIGS. 7A through 7C illustrate the three-in-one design otherwise known as the IBFD. This device consists of five components. Three UBS/BDFT screws 100a, 100b, 100c, a superior and an inferior enclosure 701, 702. The enclosures 701, 702 are attached to the UBS/BDFT screws 100a, 100b, 100c. A screw driver 705 is used to actuate the screws 100a, 100b, 100c. There are also slots 703, 704 for bone fusion material. This device is only for anterior insertion into the spine, and it covers the entire cross-sectional area of the interspace, and is thus a total IBFD. The enclosures can be made out of PEEK, titanium, cobalt chromium or any other similar substance. The structure of the device provides significant three column stability and prevents subsidence of the construct.

[0046] FIGS. 8A and 8B illustrate the individual components of the facet joint staple gun 800. It consists of a remote action mechanism which includes grip handles 801, transmission linkages 802, a drive rod 803, a cylinder 804. The drive rod 803 has a force end 805 and an action end 806.

[0047] FIGS. 9A and 9B illustrate the details of the facet joint stapler. The staple 900 has superior and inferior staple segments 901, 902. These segments 901, 902 are joined by a teethed unidirectional locking mechanism 903 having right triangular teeth 910, and a spring washer 904. The inferior surfaces 905, 906 of each staple segment 901, 902 are serrated to facilitate bony integration, and each segment has two bone piercing elements 907 with a base 908. FIG. 10 illustrates the staple 900 in the staple gun 800, in the opened position engaging the facet joints, prior to penetration and stapling.

[0048] FIGS. 11-13 illustrate the different components of the staple gun 800 and staple 900 in a detailed manner. The mechanism of action of the staple gun 800 includes engaging the staple 900 in the action end 806 of the drive rod 803 and resting in the staple guide chamfers 1201 (FIGS. 12A-13). When the staple 900 is thus engaged in the staple gun 800, the grip handles 801 are squeezed together, bringing the linkages 802 together (FIGS. 11-12C). This action is transmitted to the force end 805 of the driving rod 803 which moves upwards. This leads to upward movement of the action end 806 of the drive rod 803 in which the staple 900 is nestled, leading to the opposition of the superior and inferior segments 901, 902 of the staple, 900 and the penetration of the pins 907 into the bone. The distance of bone penetration is modulated by the pressure put on the hand grips 801. Hence graded facet joint opposition leading to different degrees of opposition and hence rigidity can be accomplished. The greater the force the greater the opposition. Thus this is a modulated not a static stapling mechanism.

2. The Surgical Method

[0049] The surgical steps necessary to practice the present invention will now be described.

[0050] The posterior lumbar spine implantation of the BDFT (UBS) screws 100, horizontal mini-plate 600 and IBFD 100a, 100b, 100c can be implanted via previously described posterior lumbar interbody fusion (PLIF) or posterior transforaminal lumbar interbody fusion (TLIF) procedures. The procedure can be performed open, microscopic, closed, tubular or endoscopic. Fluoroscopic guidance can be used with any of these procedures.

[0051] After the adequate induction of anesthesia, the patient is placed in the prone position.

[0052] A midline incision is made for a PLIF, and one or two parallel paramedian incisions or a midline incision is made for a TLIF. For the PLIF a unilateral or bilateral facet sparing hem i-laminotomy is created to introduce the BDFT (UBS) screws 100, into the disc space after it is adequately prepared. For the TLIF procedure, after a unilateral dissection and drilling of the inferior articulating surface and the medial superior articulating facet, the far lateral disc space is entered and a circumferential discectomy is performed. The disc space is prepared and the endplates exposed.

[0053] There are then multiple embodiments to choose from for an intervertebral body fusion. With the first and simplest choice, under direct or endoscopic guidance one. Two or three BDFT screws 100 can be placed. If two screws 100 are placed. One is placed on the right, and one on the left. If three are placed, the additional one can be placed more anterior and midline, such that the three screws 100a, 100b, 100c form a triangulation encompassing the anterior and middle columns of the vertebral bodies. (FIGS. 6B and 6C). Once the screws 100 are placed into the desirable intervertebral body positions, the worm drive screws 105 are turned clockwise which leads to the penetration and engagement of the superior and inferior bi-directional screws 102, 103 into the vertebral bodies above and below. BDFT screws can also be placed in angled positions if desirable (not illustrated). Bone material or alternative intervertebral fusion material can then be packed into the disc space around the BDFTs 100. The casing gear box 101 of the screws prevents subsidence of the vertebral bodies (FIGS. 1A-C). An additional option in the posterior lumbar spine is to place a horizontal mini-plate 600 underneath the thecal sac to prevent bone migration into the nerves. This plate 600 (FIGS. 6A-C) can be slid underneath the thecal sac, and secured to the right and left BDFT (UBS) screws 100. Once set, the plate 600 can be locked down with plate screw caps 606 thereby preventing movement (FIGS. 6A-C).

[0054] If further posterior column stability or rigidity is required, unilateral or bilateral, single level or multiple level facet screw stapling 900 can be performed under open, microscopic flouroscopic or endoscopic vision. Radiographic confirmation of staple position is obtained. Calibrated stapling leads to opposition of the facet joints 1000 with incremental degrees of joint opposition. This can lead to variable degrees of posterior column rigidity and/or flexibility (FIGS. 8-13).

[0055] The anterior cervical, thoracic and lumbar spine implantation of one, two or three UBS (BDFT) screws 100 can be performed in a similar manner to posterior application. Likewise a horizontal mini-plate 600 can be used to cap two BDFT screws 100. Anterior placement of the three-in-one device (IBFD) 100a, 100b, 100c into the L4/5 and L5/S1 interspaces can be performed on the supine anesthetized patient via previously described open micropscopic or endoscopic techniques. Once the disc space is exposed and discectomy and space preparation is performed, placement of one, two or three BDFT screws 100 with or without a mini-plate 600, or placement of the IBFD 100a, 100b, 100c is identical to that performed for the posterior approach.

[0056] The posterior placement of the BDFT screws 100 alone or combined with horizontal mini-plates (two-in-one) 600 or with IBFD 100a, 100b, 100c into the thoracic spine can be performed via previously described transpedicular approaches; open or endoscopic. The anterior placement of the IBFD (three-in-one) into the thoracic spine can be accomplished via a trans-thoracic approach. Once disc space exposure is obtained via either approach, all of the above mentioned embodiments can be inserted. Engagement of the devices is identical to what was mentioned above.

[0057] For anterior placement of the cervical embodiments of the BDFT screw(s) 100 with or without the horizontal cervical mini-plate 600, and the IBFD 100a, 100b, 100c embodiment, the anterior spine is exposed in the anesthetized patient as previously described for anterior cervical discectomies. Once the disc space is identified, discectomy is performed and the disc space prepared. Implantation and engagement of all devices is identical to that described for the anterior lumbar and thoracic spines.

[0058] The present invention may provide an effective and safe technique that overcomes the problems associated with current transpedicular-based thoracic and lumbar fusion technology, and with current vertical cervical plating technology, and for many degenerative stable and unstable spine diseases, and could replace many pedicle screw-based and anterior vertical-plate based instrumentation in many but not all degenerative spinal conditions. Calibrated facet joint screw staples 900 can facilitate flexible fusions and could replace current static trans-facet screws.

[0059] To our knowledge there has not been any other previously described bi-directional screw 100 for use in the spine, other joints, or for any commercial or carpentry application. The bi-directional screw 100 described herein may indeed have applications in general commercial, industrial and carpentry industries. To our knowledge the description of zero to subzero profile anterior or posterior horizontal spinal plates which traverse the diameter of the disc space has not been previously described. To our knowledge an intervertebral three-in-one construct 100a, 100b, 100c has not been previously reported. To our knowledge calibrated facet joint staples 900 have not been previously described.