Spinal disc space distractor
A distractor for separating adjacent elements, such as vertebrae. The distractor preferably has a scissors-type distracting mechanism, either in a simple scissors or double-acting scissors configuration. A set of blades is provided on each jaw such that an implant may be inserted between the spaced apart blades. The set of blades includes at least two blades.
This application is a continuation of copending U.S. patent application Ser. No. 09/879,911, filed Jun. 14, 2001, which is a continuation of U.S. patent application Ser. No. 09/411,161, filed Oct. 1, 1999, now U.S. Pat. No. 6,261,296, which claims priority to U.S. Provisional Application No. 60/102,669, filed Oct. 2, 1998, which are incorporated by reference herein in their entirety.
FIELD OF THE INVENTIONThe present invention relates to a device and method for spreading apart adjacent vertebrae of a vertebral column so that an implant may be inserted therebetween. More particularly, the present invention relates to a distractor device shaped and configured for minimally invasive insertion and use, such as for distraction of vertebrae using an anterior or anterolateral approach.
BACKGROUND OF THE INVENTIONBack pain can be caused by either one or a combination of the following: a loss of disc height, compression of nerve roots, degenerative disc disease, spondylolisthesis, and other causes. The current standard of treatment for people suffering from severe back pain requiring surgical intervention due to different types of pathology is by intervertebral fusion. Intervertebral fusion is achieved by fusing two adjacent vertebral bodies together by removing the affected disc and inserting a suitably sized implant into the disc space that allows for bone to grow between the two vertebral bodies bridging the gap left by the disc removal.
Known intervertebral fusion procedures typically involve the steps of removing a portion or all of the affected disc material, spreading apart adjacent vertebrae with a distractor, and inserting an implant into the space previously occupied by the removed disc material. This procedure can be done either from the front of the patient (anterior interbody fusion) or from the back (posterior interbody fusion). If done from the front, it is important to reduce the size of the distractor so that the procedure is as minimally invasive as possible and thus minimally interferes with and traumatizes the organs and vasculature between the vertebral region being treated and the insertion point. Posterior fusion can utilize larger implants and tools since the insertion space is more accommodating.
Current implants used for interbody fusion include allograft rings/dowels and cages such as threaded cages. However, the technique for the insertion of these implants generally does not achieve distraction because of their height limitations, thus making it difficult to restore the natural disc height. The force necessary to insert these implants (such as by drilling and tapping) may cause damage to the vertebrae or vertebral endplates at the insertion site. Moreover, allograft products and cages made out of other brittle materials (e.g., carbon fiber and ceramics) may break during insertion, particularly when distraction is not used and external force is necessary to insert the implant. Threaded cages on the other hand do not restore lordosis, and do not allow for atraumatic distraction to restore disc height. Thus, there remains a need for improvements in this area.
SUMMARY OF THE INVENTIONIn accordance with the principles of the present invention, a spinal disc distractor is provided to allow for an implant insertion technique to be performed during distraction of the disc space. The implants are slid into the disc space between the distractor blades, preferably while the blades are in contact with the upper and lower surfaces of the adjacent vertebral bodies. The distractor of the present invention is formed to be as minimally invasive and atraumatic as possible such that it may readily be used in an anterior or anterolaterial approach. Thus, the distractor of the present invention is configured to be used in the confined spaces of the human anatomy through a small surgical incision and permits the use of laparoscopic approaches like Balloon Assisted Endoscopic Retroperitoneal Gasless (“BERG”).
In a preferred embodiment, the distractor of the present invention has a scissor-like configuration with a pair of handles pivotally connected together. A distractor jaw is coupled to a distal end of each handle such that movement of the handles together draws the jaws apart to separate the vertebrae being treated. In an even more preferred embodiment, the jaws and handles are pivotally coupled together in a double-acting scissor-like configuration to further reduce the space required to move the jaws apart and thus further minimize the invasiveness of the device and procedure.
Although the handles, jaws, and distractor mechanism of the present invention may all lie in the same plane, in order to facilitate visualization of the treatment site during distraction and insertion of an implant, at least the handles may be angled away from the plane of the distractor jaws. In a preferred embodiment, the distractor mechanism is angled downwardly with respect to the jaws and the handles are angled downwardly with respect to the distractor mechanism to further enhance visualization and also to permit greater space for the implant holder adjacent the proximal end of the distractor during insertion of the implant.
A locking mechanism preferably is provided adjacent to or in the handle to maintain distraction. The locking mechanism may include a spindle or threaded bolt mounted on a first handle and passing through the second handle. An internally threaded speed nut is rotatably mounted on the threaded bolt such that movement of the speed nut along the bolt selectively inhibits movement of the second handle away from the first handle and thus maintains the vertebrae at the desired distracted position.
The blades of the distractor of the present invention are configured to increase versatility of the distractor. In a first embodiment of the present invention, the blades are removably coupled to the distractor jaws. Thus, the blades may be changed, as necessary or desired, for a given procedure or patient.
In another embodiment, the blades of the distractor are gradually curved to be out of the plane of the distractor mechanism. Because of the gradual curve, the distal end of the jaws may safely be manipulated through the patient's body with as minimal contact as possible with organs and vasculature including major blood vessels such as the vena cava and aorta. Moreover, such curvature permits insertion through a smaller incision because of the increased manipulability of the gradually curved blades through small openings and spaces.
In yet another embodiment, the blades of the distractor are configured to permit insertion of any type of implant. In particular, although certain implants may be provided with slots for engagement with a surface of the distractor blades during insertion, other implants do not have such slots. The blades of the third embodiment of the present invention are configured and sufficiently spaced apart to permit insertion of either type of implant, regardless of whether slots are provided for engaging distractor blades. The spaced apart blades may be fixed with respect to the distractor jaws, or alternatively may be removably coupled to the distractor jaws.
The spinal disc distractor of the present invention is thus designed to distract disc space atraumatically with respect to both the vertebrae and the implant during endplate preparation, implant sizing, and implant insertion. The distractor may be used in a straight anterior, anterolateral, or lateral approach, and may be used in either an open or a laparoscopic procedure. Moreover, the distractor is designed to ensure the selection of an anatomically correct implant size by permitting the annulus to be fully stretched so that the largest possible implant may be inserted and compressed upon release of the vertebrae, thereby enhancing stability and assuring correct placement of the implant. Thus, the present invention permits disc height and lordosis to be restored. The jaws are shaped and configured to preserve the endplate and the vertebral body during distraction, as well as to permit insertion of an implant during distraction. The risk of breakage of allograft implants and other cages made from brittle materials during insertion is thereby reduced.
BRIEF DESCRIPTION OF THE DRAWINGSThe detailed description will be better understood in conjunction with the accompanying drawings, wherein like reference characters represent like elements, as follows:
In accordance with the principles of the present invention, a distractor 10 is provided with a pair of handles 12a, 12b movable with respect to each other to actuate a pair of jaws 14a, 14b coupled thereto, as shown in
In order to be optimally useful for use in an anterior approach, handles 12 and jaws 14 are configured to move jaws 14 apart along distraction axis 16 a sufficient amount to adequately separate adjacent vertebrae to be treated (typically 5 mm-20 mm, most typically 13 mm-15 mm) yet to occupy a minimal amount of space within the insertion region during the procedure. Thus, handles 12 and jaws 14 preferably are pivotally coupled together in a scissors configuration such that movement of handles 12a and 12b together causes jaws 14a and 14b to move apart and effect distraction of vertebrae between which jaws 14 are positioned. Thus, proximal ends 18 of handles 12 are configured to facilitate gripping. In a preferred embodiment, the outer surface of handle proximal ends 18 are contoured to increase user comfort, as shown in
A biasing element 20, such as a pair of leaf springs, maintains handles 12a, 12b in a spaced apart configuration such that jaws 14a, 14b are close together, ready for insertion through a small incision and narrow passage through the patient in the neutral configuration of
A distractor mechanism 30 is provided such that movement of handles 12 to actuate distractor mechanism 30 causes jaws 14 to move apart to effect distraction of adjacent elements such as vertebrae. Distractor mechanism 30 may have a simple scissors configuration (such as in
An additional feature of distractor 10 which facilitates use thereof during distraction is the relative offset positions of jaws 14a, 14b, handles 12a, 12b, and distractor mechanism 30 with respect to one another, as may be appreciated in the side elevational view of
A distractor provided in accordance with the principles of the present invention is configured to distract adjacent vertebrae so that an implant may be inserted therebetween. Preferably, each jaw of a distractor formed in accordance with the principles of the present invention is provided with a blade shaped and configured to contact a vertebral endplate and also to permit insertion of an implant therebetween. Once the implant is properly positioned between the vertebral endplates, the distractor, along with its blades, may be removed from the distraction site in the patient.
In the embodiment of
Blades 44 may converge toward each other in a distal direction before actuation of distractor mechanism 30 as may be appreciated with reference to
Distracting surfaces 52a, 52b of blades 44a, 44b preferably are shaped to securely engage the vertebrae being treated, particularly the endplates thereof. In a preferred embodiment, distracting surfaces 52a, 52b are configured to securely engage the anterior lip of the vertebral endplates being treated, as shown in the isolated view of blade 44 in
In accordance with the principles of the present invention, the distractor blades preferably are configured to increase versatility of use of the distractor of the present invention. It will be appreciated that distractor 10 preferably is formed from a surgical grade sterilizable metal such that the same distractor may be used for different patients. In order to increase the versatility of distractor 10 and its usefulness for different patients and situations, at least one of blades 44a, 44b may be removably coupled to its respective jaw 14a, 14b, as illustrated in
Removable attachment of blades 44 to jaws 14 permits a plurality of differently configured blades to be used with distractor 10 depending on the situation or application. For example, the size of the blade may be selected based on the implant to be inserted, different implants potentially having differently sized slots for receiving a distractor blade. The size of the blade may also be selected depending on the size of the vertebrae being treated or the curvature of the vertebral column. For example, it may be desirable to select blades of different insertion lengths IL1, IL2, as shown in
Although the removability of blades 44 of distractor 10 provides a significant versatility advantage over prior art distractors having blades which are rigidly and fixedly connected to the remaining elements of the distractor, versatility is achievable in accordance with the principles of the present invention in other manners as well. For instance, distal end 102 of distractor 100 of
For instance, in prior art distractors, the insertion hole commonly is sized to accommodate the distance between spaced apart elements of the distractor. However, the gradual and smooth curvature of jaws 114 and blades 144 permits distractor 100 to be manipulated to fit through the insertion hole such as by “snaking” distractor 100 through. Thus, the curvature of jaws 114 of distractor is selected and configured such that the insertion hole may be sized based on the single element of the distractor with the largest cross-section. Additionally, the curvature of jaws 114 and blades 144 is smooth and selected such that upon insertion, no sharp edges are present which may injure vasculature, organs, etc., along the insertion path. The curvature thus is sufficiently gentle and wide such that jaws 114 and blades 144 are readily manipulated through the patient's body without causing internal injuries or damage. Preferably the curvature has an S-shape to permit such manipulation and rounded surfaces.
In order to provide the above-described curvature in the distal end of distractor 100, a smooth (e.g., radiused without sharp edges) curve 140 which gradually results in distal jaw ends 138 being at an obtuse angle with respect to proximal jaw ends 136 may be provided in jaws 114. Additionally, a similarly smooth and gradual curve 141 preferably is provided between distal jaw ends 138 and blades 144 to result in at least a proximal portion of distractor 100 being in a different plane from that of blades 144 for enhanced visualization as described with respect to bend 40 of distractor 10. Preferably, curve 141 results in an angle A between blades 144 and proximal jaw ends 136 of between 0°-30° and most preferably 10°. A bend 142 may also be provided in handles 112 such that proximal handle ends 118a, 118b are not in the same plane as distal jaw ends 138a, 138b and the distraction site to further enhance visualization, as described above with respect to bend 42 of distractor 10. Bend 142 may be between 0°-30° and most preferably 15°.
It will be appreciated that distractor mechanism 130 is similar to distractor mechanism 30 and the description of distractor mechanism 30 thus is applicable to distractor mechanism 130 and is not repeated herein. Preferably, if distractor mechanism 130 is similar to distractor mechanism 30, then blades 144a, 144b converge towards each other in a distal direction, as may be appreciated with reference to
Like blades 44 of distractor 10, blades 144a, 144b preferably are closer together than distal jaw ends 138a, 138b, as may be appreciated with reference to
The dimensions of blades 44a, 44b of distractor 10 and blades 144a, 144b of distractor 100 are preferably similar. The thickness T (
Versatility of a distractor formed in accordance with the principles of the present invention may alternatively be achieved by the provision of a distractor 200 as shown in
As may be appreciated upon comparison of
Vertebral engagers 254a, 254b and transverse engagement walls 256a, 256b, similar to above-described vertebral engagers 54a, 54b and transverse engagement walls 56a, 56b, may be provided to enhance engagement of blades 244a, 244b with the endplates at the treatment site as described above in connection with distractor 10. Blades 244 of distractor 200 preferably are fixedly secured to jaws 214, such as by formation of blades 244 and jaws 214 as a unitary piece. Thus, distractor 200 may readily be used in severely calcified areas requiring significant strength and durability of the distractor blades. Alternatively, blades 244 may be configured similarly to blades 440 so as to be removably coupled with jaws 214.
It will be appreciated that distractor mechanism 130 is similar to distractor mechanism 30 and the description of distractor mechanism 30 thus is applicable to distractor mechanism 130 and is not repeated herein.
It will also be appreciated that distractor mechanism 230 of distractor 200 may be a simple scissors configuration with handles 212 and jaws 214 formed along the same lever element, as may be appreciated with reference to
While the foregoing description and drawings represent the preferred embodiments of the present invention, it will be understood that various additions and/or substitutions may be made therein without departing from the spirit and scope of the present invention as defined in the accompanying claims. One skilled in the art will appreciate that the invention may be used with many modifications of structure, forms, arrangement, proportions, materials, and components and otherwise, used in the practice of the invention and which are particularly adapted to specific environments and operative requirements, without departing from the principles of the present invention. The presently disclosed embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims, and not limited to the foregoing description.
Claims
1. A distractor comprising:
- first and second handles;
- first and second jaws respectively associated with said first and second handles;
- a first set of blades extending from said first jaw; said first set of blades comprising at least a first blade and a second blade, said first and second blades being separated by a dimension sufficient to permit the complete insertion of an entire bone fusion implant therebetween;
- a second set of blades extending from said second jaw; said second set of blades comprising at least a first blade and a second blade, said first and second blades being separated by a dimension sufficient to permit the complete insertion of the implant therebetween; and
- a distractor mechanism coupled between said handles and said jaws such that movement of said handles actuates said distractor mechanism to move said jaws apart,
- wherein said first and second sets of blades are configured and adapted to contact anatomical elements to be distracted and permit the complete insertion of the entire bone fusion implant between said anatomical elements.
2. The distractor of claim 1, wherein the distractor mechanism includes an open position in which said first set of blades is spaced relative to said second set of blades, and a closed position in which at least a portion of said first set of blades contacts at least a portion of said second set of blades; and
- the first set of blades includes at least a portion that is spaced from at least a portion of the second set of blades when the distractor is in the closed position to permit placement of an implant therebetween for insertion between said anatomical elements.
3. The distractor of claim 1, wherein the distractor mechanism includes an open position in which said first set of blades is spaced relative to said second set of blades, and a closed position in which at least a portion of said first set of blades contacts at least a portion of said second set of blades; and
- the first jaw includes at least a portion that is spaced relative to at least a portion of the second jaw when the distractor is in the closed position to permit the placement of an implant prior to insertion between the first and second set of blades.
4. The distractor of claim 1, wherein the first set of blades lie in the same plane and the second set of blades lie in the same plane; and the at least first and second blades of each set are laterally spaced relative to one another.
5. The distractor of claim 1, wherein the first set of blades has an insertion length and the second set of blades has an insertion length, and the insertion length of the first set of blades is different from the insertion length of the second set of blades.
6. The distractor of claim 1, wherein the first and second set of blades are integrally attached to their respective first and second jaws.
7. The distractor of claim 1, wherein at least one of the first and second sets of blades is removably attached to its respective first and second jaws.
8. The distractor of claim 1, wherein the distractor mechanism further comprises:
- a pair of first and second proximal lever arms each having proximal and distal ends; and
- a pair of first and second distal lever arms each having proximal and distal ends,
- wherein:
- said first handle is located at said proximal end of said first proximal lever arm;
- said second handle is located at said proximal end of said second proximal lever arm;
- said first jaw is located at said distal end of said first distal lever arm;
- said second jaw is located at said distal end of said second distal lever arm;
- one of said pair of proximal lever arms and said pair of distal lever arms is crosswise pivotally coupled; and
- the other of said pair of proximal lever arms and said pair of distal lever arms is laterally pivotally coupled.
9. The distractor of claim 1, wherein the first and second jaws each include a mating fixture and the first and second set of blades each include a mating portion, wherein each mating portion is shaped for removable association with each mating fixture.
10. The distractor of claim 9, wherein each mating portion is a post and each mating fixture is a socket.
11. The distractor of claim 9, wherein each mating portion is a socket and each mating portion is a post.
12. The distractor of claim 9, wherein the mating fixture is positioned on an upper surface of the first and second jaws and at least a portion of the first and second blades extends substantially perpendicular to the upper surface of the first and second jaws.
13. The distractor of claim 1, wherein the first and second jaws are removably associated with the first and second handles.
14. The distractor of claim 1, wherein the first and second set of blades are removably associated with the first and second jaws.
15. The distractor of claim 9, further comprising a locking mechanism for locking the position of the mating portion relative to the mating fixture.
16. The distractor of claim 15, wherein the locking mechanism includes a ball portion.
17. The distractor of claim 1, wherein at least a portion of the first set of blades extends at a first angle relative to the first jaw and at least a portion of the second set of blades extends at a second angle relative to the second jaw.
18. The distractor of claim 17, wherein the first angle is substantially the same as the second angle.
19. The distractor of claim 17, wherein the first and second angles range from about 20° to 30° relative to a longitudinal axis of the distractor mechanism.
20. The distractor of claim 1, wherein the first and second set of blades include at least one curved portion.
21. The distractor of claim 1, wherein the first and second jaws include at least one curved portion.
22. A method of distracting adjacent vertebrae comprising the steps of:
- providing a distractor comprising first and second handles, first and second jaws respectively coupled to said first and second handles, a first set of spaced apart blades extending from said first jaw, a second set of spaced apart blades extending from said second jaw, and a distractor mechanism coupled between said handles and said jaws;
- positioning said first set of spaced apart blades in contact against spaced apart ends of a first vertebral endplate;
- positioning said second set of spaced apart blades in contact against spaced apart ends of a second vertebral endplate adjacent and facing said first vertebral endplate;
- actuating said distractor mechanism to distract said first and second vertebral endplates; and
- inserting an implant between said first and second sets of blades and said first and second vertebral endplates.
23. A distractor comprising:
- first and second handles;
- first and second jaws respectively associated with said first and second handles;
- a first set of blades extending from said first jaw, a second set of blades extending from said second jaw, said first and second sets of blades each comprise at least first and second blades spaced apart to contact anatomical elements to be distracted and permit insertion of an implant between said anatomical elements; and
- a distractor mechanism coupled between said handles and said jaws such that movement of said handles actuates said distractor mechanism to move said jaws,
- wherein the distractor mechanism further comprises:
- a pair of first and second proximal lever arms each having proximal and distal ends; and
- a pair of first and second distal lever arms each having proximal and distal ends,
- wherein:
- said first handle is located at said proximal end of said first proximal lever arm;
- said second handle is located at said proximal end of said second proximal lever arm;
- said first jaw is located at said distal end of said first distal lever arm;
- said second jaw is located at said distal end of said second distal lever arm;
- one of said pair of proximal lever arms and said pair of distal lever arms is crosswise pivotally coupled; and
- the other of said pair of proximal lever arms and said pair of distal lever arms is laterally pivotally coupled.
24. The distractor of claim 23, wherein the distractor mechanism includes an open position in which said first set of blades is spaced relative to said second set of blades, and a closed position in which at least a portion of said first set of blades contacts at least a portion of said second set of blades; and
- the first set of blades includes at least a portion that is spaced from at least a portion of the second set of blades when the distractor is in the closed position to permit placement of an implant therebetween for insertion between said anatomical elements.
25. The distractor of claim 23, wherein the distractor mechanism includes an open position in which said first set of blades is spaced relative to said second set of blades, and a closed position in which at least a portion of said first set of blades contacts at least a portion of said second set of blades; and
- the first jaw includes at least a portion that is spaced relative to at least a portion of the second jaw when the distractor is in the closed position to permit the placement of an implant prior to insertion between the first and second set of blades.
26. A distractor comprising:
- a proximal end having first and second handles located in a first plane;
- a distal end having first and second jaws respectively associated with said first and second handles, said first and second jaws located in a second plane different from the first;
- a first set of blades extending from said first jaw, a second set of blades extending from said second jaw, said first and second sets of blades each comprise at least first and second blades spaced apart to contact anatomical elements to be distracted and permit insertion of an implant between said first and second set of blades and said anatomical elements; and
- a distractor mechanism coupled between said handles and said jaws such that movement of said handles actuates said distractor mechanism to move said jaws apart,
- wherein the first plane is angled with respect to the second plane so as to permit visualization of the blades from the proximal end.
27. The distractor of claim 26, wherein at least one of the first and second sets of blades is removably attached to its respective first and second jaws.
28. The distractor of claim 26, wherein the first and second jaws are removably associated with the first and second handles.
29. The distractor of claim 26, wherein the first and second set of blades are removably associated with the first and second jaws.
30. The distractor of claim 26, wherein the first plane and the second plane form an angle therebetween ranging from about 5° to about 30°.
31. The distractor of claim 30, wherein the angle ranges from about 5° to about 20°.
32. The distractor of claim 30, wherein the angle is substantially 15°.
33. The distractor of claim 1, wherein the dimension separating the first set of blades is substantially identical to the dimension separating the second set of blades.
34. The distractor of claim 1, wherein the implant does not engage the first and second set of blades when the implant is inserted between said anatomical elements.
35. The distractor of claim 1, wherein the implant does not contact the first and second set of blades when the implant is inserted between said anatomical elements.
Type: Application
Filed: Apr 14, 2005
Publication Date: Aug 11, 2005
Inventors: Max Aebi (Montreal), Thomas Steffen (Montreal), David Paul (Phoenixville, PA), William Cottle (Vancouver), Beat Schenk (Nugler)
Application Number: 11/108,030