Patent Application
20240358392
The present application generally relates to a device for use in a spinal surgery. In particular, the disclosure is directed to devices and methods for the removal of intervertebral discs as part of a surgical procedure.
Disc degeneration is a condition of the spine that causes the vertebral bodies to compress the nerves that protrude from the transforaminal space. To alleviate such a condition a “spinal decompression” must be performed for which there are various procedures. During these procedures, the proper spacing between the vertebral bodies may be restored by placing an implant therebetween resulting in a fusion of the bodies. Alternatively, a protruding disc can be removed by performing a micro-discectomy.
To access the spine a large incision must be made over the affected area. While allowing access to the affected area, it is desirable to minimize the incision used in performing spinal fusion by use of minimally invasive techniques. One such technique is TLIF or transforaminal lateral interbody fusion. This procedure minimizes the risks to the patient such as infection, recovery times and the formation of scar tissue. In the case of the formation of scar tissue, this can protrude into the transforaminal space requiring further surgical revision. In performing such procedures a small incision is made and an access port such as a tube is inserted into the incision and guided to the affected region of the spine.
Regardless of the technique used, a discectomy procedure is generally necessary to remove the intervertebral disc to prepare the vertebrae for the fusion procedure. Many tools exist for performing this procedure, but most of these are manual tools that are not well suited to minimally invasive techniques. For example, most tools require manual manipulation by the surgeon requiring both surgical skill and care to avoid damage to the surrounding vertebral bodies. The use of power tools may ease the procedure, thereby reducing injury to surrounding tissues and shortening the post-operative recovery period.
During minimally invasive procedures, not only is decreased surgical times desired, but so too is the ability to work within smaller access spaces. In such procedures disc removal can be very difficult, technically demanding, and time-consuming, especially where the access window to the disc is much smaller. This limited access window also makes visualization and evaluation of the quality of the disc removal and endplate preparation very difficult.
With the reality of these technical challenges and access limitations, along with a desire to further reduce the damage caused to the patient during surgical access, the need for an improved, powered device to efficiently remove the disc material and prepare the vertebral endplates is clear.
An apparatus for use in preparing the intervertebral disc space is disclosed. The apparatus generally comprises a powered disc cutter that can be inserted through a tube and into the disc space. Once inside the disc space, the cutter can be rotated on its axis and articulated through the disc space to break up and disconnect the disc tissue from the surrounding disc tissue and disc annulus.
The device is powered by a handheld driver that utilizes a motor to impart motion, such as rotary motion, to an elongated shaft assembly having a cutting tool or assembly pivotably attached to the distal end thereof. In one possible implementation, the cutting tool is mounted to the end of the drive shaft assembly by a linkage so that the shaft may be inserted in a straight configuration down a narrow access port. The cutting assembly can spin on its axis while being articulated up to potentially 80° or 90° which provides reach across the intervertebral space. In certain implementations, the elongated shaft assembly comprises an outer sheath that surrounds an inner sheath in a manner that allows the inner sheath to move therein. The outer sheath is fixedly attached to the driver while the inner sheath is connected to the driver such that the driver can impart motion to the inner sheath. The two sheaths cooperate to allow the cutting assembly to rotate about its access. This is accomplished by mounting the outer sheath such that it translates along the longitudinal length of the inner sheath.
The cutting assembly comprises a cutting tip, flexible joints, and a drive pin. In one possible version of this implementation, each of the components is mounted on a flexible shaft that can be constructed from materials such as nitinol. The tip, along with articulating drive components, is constrained together by crimping caps onto both ends of, for example, a super-elastic nitinol shaft that goes through the center of the components. The nitinol is flexible enough to allow the full articulation and rotation of the cutter. The nitinol is pre-biased or memory shaped such that it biases toward a bend. The cutter assembly is designed to allow removal from the overall tool and replacement as a disposable assembly.
In accordance with implementations of this disclosure, a series of disc joints connects to the cutting tip and can allow for at least 10° of angulation at each interface. The number of discs can be varied to provide the desired angle of total articulation. As the number of discs is reduced, the amount of angulation required at each interface is increased. By way of example, to reach the same 80° of angulation with 3 discs, there would be 4 interfaces needing to angle 20° each.
The cutting assembly includes a cutting tip which can have a variety of shapes. One configuration is a tip with jagged edges which grab and retain disc material. The design of the tip is such that it can easily cut tissue but is not suited to cut harder material such a vertebral bone without exerting greater and purposeful effort. Alternatively, the cutting tip may be replaced by a shaft with roughened surfaces. The shaft can be biased to incrementally bend in a range of angles as it is moved through a desired cutting motion.
The linkage assembly and the cutting tool are connected to the inner shaft. When the outer sheath is in a first position, it covers the linkage. As the outer sheath is translated proximally, it uncovers a portion of the distal end of the inner shaft. The nitinol shaft acts upon the joints to articulate the tip in an angular direction. The linkage assembly allows the tip to rotate about a proximal axis.
The surgeon imparts motion to the outer sheath by depressing a handle, in one possible implementation. The handle is pivotably connected to a housing that connects the outer sheath to the driver. The housing is fixed to the driver and includes an elongated section. The outer sheath includes a collar at its proximal end that is mounted on the elongated section. Interposed between the collar and the main section of the housing sits an actuation spring. As the handle is depressed, the retention spring is compressed such that upon release of the handle the spring is released, and the outer sheath is returned to its original position. At such point, the distal end of the inner sheath and the linkage mounted thereon are covered, returning the cutting tip to a straight configuration. This allows the surgeon to withdraw the shaft assembly back through the narrow window.
The foregoing has outlined rather broadly the more pertinent and important features of the device so that the detailed description that follows may be better understood. Additional features will be described hereinafter which form the subject of the claims of the invention. It should be appreciated by those skilled in the art that the conception and the disclosed specific methods and structures may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the device. It should be realized by those skilled in the art that such equivalent structures do not depart from the spirit and scope of the appended claims.
The above and other objects, features and advantages of the present disclosure will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:
Exemplary embodiments are described herein to provide a detailed description of the present disclosure. Variations of these embodiments will be apparent to those of skill in the art. Moreover, certain terminology is used in the following description for convenience only and is not limiting. For example, the words “right,” “left,” “top,” “bottom,” “upper,” “lower,” “inner” and “outer” designate directions in the drawings to which reference is made. The word “a” is defined to mean “at least one.” The terminology includes the words above specifically mentioned, derivatives thereof, and words of similar import.
The device 10 comprises a powered unit 12, a shaft assembly 20 and a cutting assembly 100. The power unit 12 is preferably handheld and is designed to have an ergonomic design for ease of operation and comfort. The power unit 12 can feature an electric motor that is either powered by plugging into a power source or by battery. A replaceable and rechargeable battery pack can be placed along the base of the unit 12 and can be recharged in sterile conditions.
As shown in
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As illustrated in
As shown in
Each of the cutting tip 102, disc joints 105 and drive pin 114 are mounted on a flexible shaft 116 that can be constructed from materials such as nitinol. The tip 102, along with articulating drive components or disc joints 105 is constrained together by crimping caps 112A and 112B onto a super-elastic nitinol shaft 116 that runs through the center of the components. The nitinol is flexible enough to allow the full articulation and rotation of the cutting tip 102. The nitinol is pre-biased or memory shaped such that it biases toward a bend. Thus, as outer sheath 24 is withdrawn in increasing amounts the cutting assembly bends to an increasing angulation.
The cutter assembly 100 is designed to allow removal from the overall tool and replacement as a disposable assembly. The cutting tip 102 can have a variety of shapes and configurations. One configuration is a tip with jagged cutting edges 102 which grab and retain disc material. The design of the tip 102 is such that it can easily cut tissue but is not suited to cut harder material such a vertebral bone without exerting greater and purposeful effort. Alternatively, the cutting tip 102 may be replaced by a shaft with roughened surfaces. Such a shaft can be biased to incrementally bend in a range of angles as it is moved through a desired cutting motion. Still another cutter geometry implementation may comprise multiple individual, metallic strands spaced and otherwise configured to reduce the tendency to cut into bone. Still other cutter configurations and geometries are possible and are likewise contemplated by this disclosure.
The inner sheath 24 is connected to the powered drive 12 so that the drive 12 imparts motion, such as rotational motion, thereto. As shown in
Outer sheath 22 is actuated by means of an assembly comprising a handle or trigger 16, a spring 26 and a mounting nut 36. The proximal end of elongated extension 42 includes external threads 43. The mounting nut 36 includes internal threads such that the nut is threaded onto the proximal, externally threaded end of elongated extension 42. Interposed between the collar 44 of outer shaft 24 and the mounting nut 36 is a spring 26. As shown with additional reference to
Located at the top of the housing 40 is an upper handle mount 34 for upper handle 14. Upper handle mount 34 may provide an alternate to handle 16. In addition, as the cutting tip 102 is being articulated, upper handle 14 can be correlated to the tip 100 such that it may be employed to track the angular position of the cutting tip.
In operation, the shaft assembly is maneuvered through the surgical access port with the handle in the position shown in
The present disclosure includes that contained in the appended claims as well as that of the foregoing description. Although this invention has been described in its exemplary forms with a certain degree of particularity, it is understood that the present disclosure of has been made only by way of example and numerous changes in the details of construction and combination and arrangement of parts may be employed without departing from the spirit and scope of the invention.
