GROWTH AND MOTION SPARING TETHERS AND BONE ANCHOR IMPLANTS FOR THE TREATMENT AND CORRECTION OF SPINE DEFORMITIES

Abstract

Tethers, devices and bone anchor implants are provided for the correction and treatment of spine deformities including scoliosis.

Claims

1. A system for correction of spinal deformities comprising: (a) two or more bone anchor implants each having at least two tines, each tine having barbs on at least one surface thereof to engage the bone of a vertebral body; each implant having at least two recesses adapted to accept screws for securing the implant to a vertebral body; each bone anchor implant further having a groove or channel adapted to allow unrestricted blood flow through the vertebral vessels; each implant further having a groove for accepting a tether, the groove having a locking device for securing the tether to bone anchor implant; and (b) a tether for connecting the bone anchor implants one to another.

2. The system of claim 1 wherein the bone anchor implant has two tines opposed to each other, having barbs on the opposed surfaces thereof.

3. The system of claim 1 wherein the bone anchor implant has four tines, arranged in two opposed pairs, each opposed pair having barbs on the opposed surfaces thereof, wherein the bone anchor implant has one recess adapted to accept a screw positioned between each pair of adjacent tines.

4. The system of claim 1 wherein the bone anchor implant has two tines, offset from each other, each having barbs of the surface thereof to engage the bone of a vertebral body, wherein the bone anchor implant has a recess adapted to accept a screw positioned opposite each tine.

5. The system of claim 1 wherein the locking device is a set screw.

6. The system of claim 1 further comprising at least two screws for each bone anchor implant, for securing the implant to a vertebral body.

7. The system of claim 6 wherein the screws are bicortical screws.

8. The system of claim 1 wherein the tether is rigid.

9. The system of claim 1 wherein the tether is flexible.

10. The system of claim 1 wherein some portions of the tether are rigid, and other portions are flexible.

11. The system of claim 1 wherein the tether is bioabsorbable.

12. A tool for the emplacement of a bone anchor implant having tines, comprising a cannula adapted to enclose the tines of the implant, and enclosing a grasper/inserter that engages the implant, which further encloses a screw guide for guiding the insertion, removal, and adjustment of one or more screws that secure the implant to a vertebral body, and one or more screws that secure a tether to the implant.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIG. 1 depicts an exploded perspective view of a first embodiment of the present invention, showing an anchor having four tines for engaging the vertebral body. as well as a locking collar and set-screw for securing a tether or cable to the anchor.

[0024] FIG. 2 depicts an assembled perspective view of the first embodiment of the present invention.

[0025] FIG. 3 depicts section perspective view of the first embodiment of the present invention.

[0026] FIG. 4 depicts a perspective view of the human spinal column, showing three anchors according to the first embodiment of the present invention in place on three vertebral bodies, and interconnected by a tether or cable.

[0027] FIG. 5 depicts a perspective view of a second embodiment of the present invention, showing an anchor having four tines for engaging the vertebral body. as well as a set-screw for securing a tether or cable to the anchor.

[0028] FIG. 6 depicts a perspective view of a third embodiment of the present invention, showing an anchor having two tines for engaging the vertebral body.

[0029] FIG. 7 depicts an exploded plan view of a fourth embodiment of the present invention, showing a screw having a cam.

[0030] FIG. 8 depicts a perspective view of a fifth embodiment of the present invention.

[0031] FIG. 9 depicts another perspective view of the fifth embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0032] In a preferred embodiment, as shown in perspective view in FIG. 4, the bone anchor implant 10 of the present invention is implanted and anchors to the lateral aspect of the bone of the vertebral body while minimizing dissection of the overlying tissue and preserving the segmental blood supply of the spine. The several anchors 10 are joined together by tether 20, which is locked in place by locking caps 30.

[0033] As depicted in FIG. 1, the bone anchor implant assembly 2 is comprised on anchor 10 that has four tines 12 shaped to allow them to span the segmental blood vessels and therefore on insertion, do not need these vessels and the overlying tissue such as the pleura to be dissected and coagulated. In addition, anchor 10 is adapted to receive locking cap 30, and it, in turn, receives set screw 40. Together locking cap 30 and set screw 40 retain tether in 20 in locked relation to anchor 10.

[0034] FIG. 2 further depicts implant assembly 2 with tether 20 locked in place by set screw 40.

[0035] FIG. 3 further depicts implant assembly 2 in cross section, showing barbs 14, and groove 16 on the underside of the anchor 10 between the tines 12 that accommodates the segmental blood vessels.

[0036] FIG. 5 depicts an alternative embodiment in which tether 20 may optionally have a semicircular cross-section. Set screw 40 is directly inserted into the body of the implant assembly which is threaded to accept it.

[0037] FIG. 6 depicts another alternative embodiment of the present invention. Tines 12 having barbs 14 engage the vertebral body. Outer channel 50 accommodates blood vessels routed around the anchor 10. Inner channel 60 is adapted to receive a screw, particularly the screw shown in FIG. 7.

[0038] FIG. 7 depicts a bicortical screw 100 having tether-receiving groove 118 in its head. Located within groove 118 is a pair of opposing eccentric cams 120, retained in place by cam screws 122. The head of screw 100 is adapted to receive locking cap 30 and set screw 40. In use, a tether 20 is placed between cams 120 and tensioned. Cams 120 allow one-way motion and grip tether 20. Once proper tension is achieved, set screw 40 is tightened to lock tether 20 in place.

[0039] FIGS. 8 and 9 depict another embodiment of screw 100, in which a set of ridges 130 grip tether 20 (not shown). Locking cap 30 and set screw 40 then serve to retain and lock tether 20 in place. Central passage 140 allows the passage of a guide wire or similar instrument through the axis of the screw.

[0040] In every embodiment, the anchors 10 and the inserted screws 100 are placed to avoid the blood vessels as well as to avoid injury to the endplates and discs of the vertebral bodies that the bone anchor implant are being placed.

[0041] The tether 20 is made of bio-compatible cable that may be metallic or non-metallic. The material of the tether for example may be nonabsorbable or bioabsorbable. Portions of the tether 20 for example, may be rigid while some portions may be flexible or the tether or tethers 20 may be entirely flexible. The tether-receiving groove 18 (or 118) in each bone anchor implant is aligned with the similar tether-receiving groove 18 (or 118) in the adjacent bone anchor implant above and below, and thus the tether is attached to multiple bone anchor implants. As depicted, the groove has threads above the space for the tether to receive a set screw 40.

[0042] An inserting device (not shown) has a sleeve of metal or plastic that slides over the barbed tines allowing safe passage into the chest cavity through a valved endoscopic trocar, thus allowing easy passage through the valves, as well as protecting the lung and blood vessels from sharp edges as the bone anchor implant enters the hemithorax under thoracoscopic control and visualization. The inserting device also may be provided with two or more grooves or channels that allow the screws and screw driver to be inserted after the bone anchor implant has been placed into the vertebral body.

[0043] The bone anchor implants of the present invention are placed sequentially into the lateral aspect of the vertebral body through valved endoscopic trocars that are placed in the intercostal space under thoracoscopic visualization. Using the present invention the bone anchor implants can be placed safely without sacrificing soft tissue and blood vessels. Additionally, biplanar fluoroscopy can be utilized to ensure correct placement in each vertebral body. After insertion of all the bone anchor implants into the vertebral bodies spanning the deformity and confirming accurate placement utilizing thoracoscopy and fluoroscopy the tether is inserted into the chest cavity through the previously placed valved trocars again under thoracoscopic visualization. The tether is sequentially placed into the receiving groove or recess in this embodiment in each bone anchor implant. In one embodiment after the tether is placed in all the bone anchor implants the tether is locked or tightened into place, using, for example, a set screw or locking screw, in the most cephalad bone anchor implant. Having locked or fastened the tether to the most cephalad bone anchor implant, the tether is tightened and all the slack is removed and the next set screw or locking screw is placed thus sequentially fastening the tether. In another embodiment the tether may first be fastened in the middle bone anchor implant, which in this example may be at the apex of the deformity of the spine, and subsequently the tether is tightened and locked or screwed into place above and below this. After all the bone anchor implants have received the tether and the tether or tethers have been tightened sequentially under thoracoscopic and or fluoroscopic visualization the excess tether above and below the most cephalad and most caudad bone anchor implant is cut and the procedure is complete.

[0044] The present invention allows for conservation and preservation of the segmental blood supply of the spine and spinal cord as well as avoiding damage to the intervertebral disc, thus mitigating any damaging effects of the treatment to the spine and spinal cord as well as to the growth and motion of the spine. All other prior art devices such as screws for anterior vertebral body tethering require coagulation and interruption of the segmental blood supply of the spine and spinal cord, thus potentially risking injury from ischemia to the spine, discs and spinal cord. The present invention does not require the coagulation, interruption, mobilization or damage to this segmental blood supply, thus additionally making the minimally invasive method less complex, safer and with less risk of bleeding. It is less complex because there is no need to interfere with the segmental blood vessels that are branches from the aorta and can rapidly bleed if damaged without prior control.

[0045] Since the device of the present invention does not have to be inserted through the entire vertebral body and does not require multiple steps for insertion (e.g, does not require placement of a staple followed by a tap under fluoroscopy, as needed by a bicortical screw, as needed by the current methods it makes the operative procedure much simpler, quicker and safer.

[0046] In addition, since the device is uniquely designed to be inserted through currently available valved endoscopic ports the procedure can be performed thoracoscopically without any large thoracic or lumbar incision for implanting in the thoracic and lumbar spine.

[0047] While the present invention has been described in its preferred embodiments, it is to be understood that the words which have been used are words of description rather than of limitation and that changes may be made within the purview of the appended claims without departing from the true scope and spirit of the invention in its broader aspects. Rather, various modifications may he made in the details within the scope and range of equivalents of the claims and without departing from the spirit of the invention. The inventor further requires that the scope accorded their claims be in accordance with the broadest possible construction available under the law as it exists on the date of filing hereof (and of the application from which this application obtains priority, if any) and that no narrowing of the scope of the appended claims be allowed due to subsequent changes in the law, as such a narrowing would constitute an ex post facto adjudication, and a taking without due process or just compensation.