Multi-lumen spinal implant guide and method

Details Multi-lumen spinal implant guide and method Multi-lumen spinal implant guide and method

1998-05-19

2001-01-09

Manahan, Todd E. (Department: 3738)

Prosthesis (i.e., artificial body members), parts thereof, or ai

Implantable prosthesis

Bone

C606S064000

Reexamination Certificate

active

06171339

ABSTRACT:

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
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 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 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.
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.
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 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 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 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 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 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 appropriate 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 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 sp

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