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MULTI-LUMEN SPINAL IMPLANT GUIDE
FIELD OF THE INVENTION
This invention pertains to intervertebral fusion. Specifically, the invention is directed to instrumentation and methods for insertion of spinal implants between opposing vertebral bodies.
BACKGROUND OF THE INVENTION 10
Chronic back problems can cause pain and disability for a large segment of the population. Frequently, the cause of back pain is traceable to diseased disk material between opposing vertebrae. When the disk material is diseased, the 15 opposing vertebrae may be inadequately supported, resulting in persistent pain.
Surgical techniques have been developed to remove the diseased disk material and fuse the joint between opposing vertebral bodies. Arthrodesis of the intervertebral joint can 20 reduce the pain associated with movement of an intervertebral joint having diseased disk material. Generally, fusion techniques involve removal of the diseased disk, drilling a bore for receiving the implant and inserting the implant between the opposing vertebral bodies. 25
Spinal fusion implants and related surgical instruments for implanting a fusion device are known and disclosed in, for example, U.S. Pat. Nos. 5,741,253; 5,658,337; 5,609, 636; 5,505,732; 5,489,308; 5,489,307; 5,484,437; 5,458, 638; 5,055,104; 5,026,373; 5,015,247; and 4,961,740. 30
Procedures for fusing an intervertebral joint space typically include placement of at least two cylindrical implants in parallel arrangement between the opposing vertebrae. Recently, non-circular implants have been introduced that 35 provide for placing parallel implants in close proximity to one another. Examples of such implants are disclosed in, for example, U.S. Pat. Nos. 5,658,337; 5,593,409; and 5,489, 307, the entire disclosures of which are incorporated herein by reference. These non-circular implants may be referred to 40 as reduced lateral profile (RLP) implants and typically have a side wall geometry that permits placement of two RLP implants or one RLP and one cylindrical implant in closer proximity to one another. Thus, greater surface area support of the intervertebral space and/or increased distraction of the 45 disk space can be provided for a given medial/lateral dimension of the vertebral body.
Some presently available systems for implanting fusion devices permit for preparing an implant site through a hollow tube. Procedures for preparing an implant site 50 through a single hollow tube are shown in, for example, U.S. Pat. Nos. 5,505,732; 5,484,437; and 5,489,307. The disclosure of each of these patents are incorporated herein by reference. In some procedures, the implants are also inserted into the prepared site through the hollow tube. Preparing the 55 implant site by passing instruments through a hollow tube advantageously provides for an isolated surgical field with reduced chance of injury to soft tissues surrounding the surgical site.
However, generally, several steps are required for appro- 60 priate placement of the implants using present hollow tube systems. These steps include inserting a spacer into the disk space to distract one side of the intervertebral space, then inserting a second spacer for distracting the second side of the vertebral space, followed by placement of the hollow 65 tube over a guiding mechanism to orient the longitudinal angulation of the implant site. Once the hollow tube is
secured in proper alignment, reamers, bores, taps, or other instruments are passed through the hollow tube to prepare the implant site. Either before or after the implant is inserted into the first site, the hollow tube is removed and the procedure is repeated on the opposite side.
Present procedures for placement of an implant through a hollow tube help to reduce the chance of iatrogenic tissue trauma caused by the implant procedure. However, while known procedures provide for reduced chance of injury, the surgeon's accuracy in the relative placement of the hollow tube between the first and second sides is still a matter of guess work and repeated verification using fluoroscopy or radiographic monitoring is needed. Also, the need for separate placement of the hollow guide tube using present methods (i.e., one placement for each implant) increases the possibility for relative misalignment of the implants to occur during insertion.
Thus, there is a continuing need for the precision, safety and ease of placement of spinal fusion implants. There is also a need for implant insertion systems that accommodate implants having non-circular cross-sectional geometries. The present invention is directed to addressing these needs.
SUMMARY OF THE INVENTION
The present invention increases the ease and enhances the precision of placement of spinal fusion implants between opposing vertebral bodies. Spinal implant procedures using the instrumentation and methods of the invention also reduce the number of steps necessary for implantation. The invention is particularly advantageous for inserting implants in close proximity.
Throughout the specification, guidance may be provided through lists of examples. In each instance, the recited list serves only as a representative group. It is not meant, however, that the list is exclusive.
In one embodiment, the invention provides a multi-lumen guide for preparing a spinal implant surgical field. In a preferred embodiment, the multi-lumen guide provides a surgical field for insertion of spinal implants in close proximity. According to this embodiment, the multi-lumen guide includes a first elongate lumen having a first cross-sectional geometry and a second elongate lumen having a second cross-sectional geometry. The elongate lumens are adjacent and parallel to one another with overlapping cross-sectional geometries. In one embodiment, the cross-sectional geometry of at least one of the lumens is circular.
At the distal end, a multi-lumen guide can include an anchoring arrangement for securing the guide to the vertebral bodies. The anchoring arrangement can include teeth which can be embedded into the vertebral body. In addition, the distal end of the guide can include one or more laterally positioned paddles which help reduce the chance of tissues outside the surgical field entering into the surgical field. In a preferred embodiment, one or more of the walls of the multi-lumen guide can also include an opening, such as a longitudinal slot, which, in addition to other advantages, facilitates cleaning of the guide.
The multi-lumen guide can be included in a kit also including one obturator for each lumen. For a multi-lumen guide having a circular cross-sectional geometry, at least one of the obturators is also circular. If the lumens of the multi-lumen guide have an overlapping circular geometry, at least one obturator has an elongate flat surface parallel to the longitudinal axis of the obturator. Preferably the obturators also have an attachment system for attaching a distraction spacer to the obturator.
The invention also provides a drill depth guide. In one embodiment, the drill depth guide is a spacer cap that can be placed at the proximal end of the multi-lumen guide to control the depth of a bore made into the vertebral bodies during a procedure according to the invention.
The invention also provides a method for implanting a spinal implant into a disk space between opposing vertebral bodies. The method is particularly advantageous for placement of two spinal implants in close proximity. According to the method, a first distraction spacer is placed into a first side of a disk space between opposing vertebral bodies and a second distraction spacer is placed into the second side of the disk space. A first lumen is then placed across the first side of the disk space over the first distraction spacer and a second guide lumen is placed across the second side of the disk space over the second distraction spacer. Subsequently, one of the distraction spacers is removed for preparing a first bore for receiving a spinal implant. After preparing the first bore, a second bore is prepared. As described herein, in a preferred embodiment, the first and second distraction spacers are placed into the disk space simultaneously. In addition, a multi-lumen guide of the invention also provides for simultaneously positioning of the first and second guide lumens across the disk space.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a top plan view of a multi-lumen guide according to the invention;
FIG. 2 is a side view of the multi-lumen guide of FIG. 1;
FIG. 3 is a cross-section view taken through 3—3 of the multi-lumen guide of FIG. 1;
FIG. 4 is a side view of an embodiment of a reduced lateral profile obturator of the invention;
FIG. 5 is a side view of the embodiment of the obturator of FIG. 4 rotated 90°;
FIG. 6 is an end-on view of the proximal end of the obturator of FIG. 4;
FIG. 7 is an end-on view of the distal end of the obturator of FIG. 6;
FIG. 8 is an embodiment of a handle for attaching to an obturator such as that illustrated in FIGS. 4-7;
FIG. 9 is an embodiment of a cylindrical obturator according to the invention;
FIG. 10 is a cross-section view taken through 10—10 of the obturator of FIG. 9;
FIG. 11 is a long side view of an embodiment of a drill depth guide of the invention;
FIG. 12 is an end-on view through the proximal end of the drill depth guide of FIG. 11;
FIG. 13 is an end-on view through the distal end of the drill depth guide of FIG. 11;
FIG. 13a is an end-on view of the distal end of a second embodiment of a drill depth guide;
FIG. 13fc is a short side view of the embodiment of a drill depth guide of FIG. 13a.
FIG. 14 is a longitudinal cross-section view taken through line 14—14 of the drill depth guide of FIG. 13;
FIG. 15 illustrates alignment of the distal ends of two distraction spacers attached to obturators;
FIG. 16 is a perspective view of a multi-lumen guide and obturator assembly at the anterior margins of opposing vertebral bodies;
FIG. 17 is a proximal end-on view of a reduced lateral profile obturator and a cylindrical obturator within the multi-lumen guide;
FIG. 18 is a proximal end-on view through a multi-lumen guide having a reduced lateral profile obturator on the left side and a reduced lateral profile implant on the right side; and
5 FIG. 19 is an anterior view of an intervertebral disk space between opposing vertebrae that has been implanted with a cylindrical implant on the left side and a reduced lateral profile implant on the right side.
10 DETAILED DESCRIPTION OF THE
The instruments and methods of the present invention facilitate the ease and accuracy of placement of multiple spinal implants into a vertebral space between opposing
15 vertebrae. The complementary interaction of the herein disclosed component instruments can also reduce the number of intraoperative images needed to establish the relative alignment of the implants during an implant procedure.
2Q The ability to enhance the accuracy of alignment between two implants inserted into the intervertebral disk space according to the procedures of the invention is facilitated by early establishment and continued maintenance of parallel operating fields at multiple implant sites. Once the surgeon
25 has determined the angular orientation of the implant (e.g., relative to the sagittal and/or transverse plane of the vertebral column), the instrumentation disclosed ensures that the relative positioning of the implants is maintained throughout preparation of the bores that will receive the implants.
3Q Some instruments useful with the new instruments described herein are known and disclosed in, for example, U.S. Pat. No. 5,489,307 and co-pending patent application Ser. Nos. 09/045,213 and 09/036,165, the entire disclosures of which are incorporated herein by reference. These dis
35 closures include various distraction plugs, guide pins, reamers, taps, etc., some which are described in more detail below.
It will be appreciated that the present procedures are applicable for use with a wide variety of implants including
40 threaded implants and non-threaded implants. The term "implant" as used herein includes bone implants (e.g., autograft, allograft, artificial bone) and non-bone implants made from titanium or other implantable material. In preferred embodiments, the instruments and methods disclosed
45 are advantageously used for insertion of implants having a reduced lateral profile as disclosed in U.S. Pat. Nos. 5,609, 636, 5,658,337 and co-pending patent application Ser. Nos. 09/045,213 and 09/036,165, the entire disclosures of which have previously been incorporated herein. In one
50 embodiment, the instruments and methods of the invention can advantageously be used for insertion of a reduced lateral profile implant adjacent to a cylindrical implant such as disclosed in U.S. Pat. Nos. 5,609,636 and 5,658,337.
55 Detailed Description of the Illustrated Embodiment
Referring to the several drawing figures in which identical elements are numbered identically throughout, a description of embodiments of the invention will now be provided. 1. Instruments
60 A. Multi-Lumen Guide
FIGS. 1-3 illustrate one embodiment of a multi-lumen guide 10. Multi-lumen guide 10 includes a distal end 11 and a proximal end 12. The top plan view of FIG. 1 illustrates that multi-lumen guide 10 includes a first elongate lumen 13
65 surrounded by an elongate wall 14 and a second elongate lumen 15 surrounded by elongate wall 16. Referring to FIG. 3, taken at line 3—3 of FIG. 1, it will be appreciated that in