Patent Application
20050261692
The field of the invention pertains to medical devices and methods for removing tissue, and in particular, vertebral bone and intervertebral disc tissue.
The spinal column consists of thirty-three bones called vertebra, the first twenty-four vertebrae of which make up the cervical, thoracic, and lumbar regions of the spine and are separated from each other by “pads” of tough cartilage called “intervertebral discs,” which act as shock absorbers that provide flexibility, stability, and pain-free movement of the spine.
A person may develop any one of a variety of debilitating spinal conditions and diseases. For example, as illustrated in
Often, inflammation from disc herniation can be treated successfully by nonsurgical means, such as rest, therapeutic exercise, oral anti-inflammatory medications or epidural injection of corticosterioids. In some cases, however, the disc tissue is irreparably damaged, in which case, surgery is the best option.
Besides disc hernias, other debilitating spinal conditions or diseases may occur. For example, spinal stenosis, which results from new bone and soft tissue growth on a vertebra, reduces the space within the spinal canal. When the nerve roots are pinched, a painful, burning, tingling, and/or numbing sensation is felt down the lower back, down legs, and sometimes in the feet. As illustrated in
Another debilitating bone condition is a vertebral body compression fracture (VCF), which may be caused by spinal injuries, bone diseases such as osteoporosis, vertebral hemangiomas, multiple myeloma, necorotic lesions (Kummel's Disease, Avascular Necrosis), and metastatic disease, or other conditions can cause painful collapse of vertebral bodies. VCFs are common in patients who suffer from these medical conditions, often resulting in pain, compromises to activities of daily living, and even prolonged disability.
On some occasions, VCFs may be repaired by cutting and removing damaged bone tissue inside a vertebra to create a void, and then injecting a bone cement percutaneously into the void. This is typically accomplished percutaneously through a cannula to minimize tissue trauma. The hardening (polymerization) of the cement media serves to buttress the bony vault of the vertebral body, providing both increased structural integrity and decreased pain associated with micromotion and progressive collapse of the vertebrae.
Thus, it can be appreciated that in many spinal treatment procedures, bone and/or disc tissue must be removed in order to release pressure from neural tissue or rebuild the vertebra. In order to access a target site, a physician can insert an access cannula through a patient's skin to reach target bone and/or disc tissue to be removed. A tissue removal probe can then be inserted through the cannula and be used to remove target tissue, such as the gel-like nuclear tissue within the intervertebral disc or the cancellous bone tissue within the vertebral body. Notably, such tissue removal probe is laterally constrained within the cannula (or if a cannula is not provided, constrained by the many layers of tissue that the device must traverse to reach the target tissue), and thus, can only be effectively moved along its longitudinal axis, thereby limiting the amount of tissue that can be removed to the tissue that is on-axis. As such, the tissue removal probe may have to be introduced through several access points within the anatomical body (e.g., the disc or vertebral body) that contains the target tissue in order to remove the desired amount of the tissue. As can be appreciated, such technique increases the time of the spinal procedure as well as surgical risk.
Tissue removal probes having steering capability have been used to overcome the above described problem. Such tissue removal probes generally have a steering wire secured to a distal end of the probe shaft. The steering wire can be tensioned during use, which in turn, causes the distal end of the probe to bend. By allowing the tissue removal probe to bend while the probe is laterally constrained within the access cannula (or the layers of tissue if a cannula is not provided), the distal end of the tissue removal probe can be steered to reach target tissue that cannot be normally reached by tissue removal probes having a straight configuration. However, use of a steering wire to bend a tissue removal probe may not provide sufficient rigidity for the probe to maintain its bent shape during use. For example, during use, surrounding tissue at a target site may exert a force on the tissue removal probe, which causes the probe to unbent itself. This in turn limits the range of target area which the tissue removal probe can reach.
A rigid tissue removal probe can be provided with a bend distal end, so that off-axis tissue can be reached. The bend distal probe end, however, increases the profile of the probe, thereby requiring the access opening through which the probe is introduced into the patient to be increased, thereby increasing patient discomfort and recovery time. In addition, the curvature of the bent distal end is fixed, thereby limiting access to the off-axis tissue.
There, thus, remains a need to provide for improved tissue removal device and methods for use during spinal treatment and other surgeries.
In accordance with the present inventions, a medical probe is provided. The medical probe comprises a probe shaft having proximal and distal shaft portions that can move relative to each other, and an operative element, such as a tissue removal element, associated with the distal shaft portion. In one embodiment, the proximal and distal shaft portions are rigid and straight to facilitate percutaneous introduction of the probe into the patient, but may be semi-rigid or flexible and/or curved as well. The medical probe may optionally have a drive shaft disposed within the probe shaft, in which case, the operative element may be mounted to the drive shaft. The operative element may be variously associated with the distal shaft portion. For example, if the operative element is a tissue removal element, the distal shaft portion may include a window through which the tissue removal element is exposed. Or the tissue removal element may extend distally of the distal shaft portion. In one embodiment, the operative element, as a tissue removal element, is rotatable, but alternatively, may move in other directions, e.g., longitudinally, in order to remove tissue. The medical probe may optionally have an adapter configured to mate with a drive unit.
In accordance with a first aspect of the present inventions, the proximal and distal shaft portions can be positioned relative to each other between axially aligned and axially non-aligned relationships. The shaft portions may be, e.g., rotatably or hingedly coupled to each other.
In accordance with a second aspect of the present inventions, the proximal shaft portion has a first beveled end, and the distal shaft portion has a second beveled end rotatably engaged with the beveled end. In this manner, the respective beveled ends interact with each other, such that an angle formed between the shaft portions can be varied when the shaft portions are rotated relative to each other. In one embodiment, the beveled ends are beveled at the same angle, so that the proximal and distal shaft portions can be placed in an axially aligned relationship. The medical probe may optionally comprise a rod rotatably disposed through the proximal shaft portion and fixedly coupled to the distal shaft portion. In this manner, the distal shaft portion can be rotated relative to the proximal shaft portion by rotating the rod. In this case, the medical probe may optionally comprise a deformable connector coupled between the rod and the distal shaft portion adjacent an interface between the proximal and distal shaft portions. In this manner, stress between the rod and distal shaft portion can be minimized.
In accordance with a third aspect of the present inventions, the medical probe comprises a hinge coupled between the proximal and distal shaft portions, such that an angle formed between the shaft portions can be varied when the shaft portions are hinged relative to each other. The medical probe may optionally comprise at least one pull wire disposed through the proximal shaft portion and fixedly coupled to the distal shaft portion. In this manner, the distal shaft portion can be hinged relative to the proximal shaft portion by pulling the pull wire(s). In one embodiment, the hinge comprises a pin mounted to the distal shaft portion, in which case, a pair of pull wires can be counterwound around the pin. In this manner, the distal shaft portion can be hinged relative to the proximal shaft portions in opposite directions by alternately pulling on the pull wires.
In accordance with a fourth aspect of the present inventions, a method of performing a medical procedure is performed on a patient. The method comprises introducing the probe into the patient while the proximal and distal probe portions are in an axially aligned relationship. The method further comprises placing the proximal and distal shaft portions in an axially non-aligned relationship, and then operating the operative element. Thus, it can be appreciated that the probe can be introduced along a straight path via a small opening within the patient, and then articulated to reach tissue that is off-axis from the path. In one preferred method, the operative element is operated after the distal shaft portion has been rotated relative to the proximal shaft portion. If the medical procedure involves removing tissue, such as bone tissue or intervertebral disc tissue, the operative element, as the tissue removal element, can be rotated to remove the tissue.
In accordance with a fifth aspect of the present inventions, the proximal and distal shaft portions are configured to rotate relative to each other, and the medical probe further comprises a rod disposed through the proximal shaft portion and fixedly coupled to the distal shaft portion, and an actuator mounted to the proximal portion in an axially sliding relationship. The rod comprises an obliquely extending slot, and the actuator comprising a pin slidably engaged within the slot. In this manner, axial movement of the actuator rotates the distal shaft portion via the rod. In one embodiment, reciprocatable axial movement of the actuator may rotate the distal shaft portion relative to the proximal shaft portion. The proximal and distal shaft portions may be rigid, but alternatively may be semi-rigid or flexible. If a drive shaft is provided, it can extend through the rod.
In accordance with a sixth aspect of the present inventions, the medical probe further comprises a drive shaft rotatably disposed within the probe shaft, in which case, the operative element will be mounted to the drive shaft. The drive shaft has a proximal rigid shaft portion associated with the proximal probe shaft portion, a distal rigid shaft portion associated with the distal probe shaft portion, and a linkage (e.g., a bellow, coil, U-joint, or beveled gear set) coupling the proximal and distal drive shaft portions. In this manner, the drive shaft may bend at the interface between the proximal and distal probe shaft portions without undergoing excessive stress.
Other and further aspects and features of the invention will be evident from reading the following detailed description of the preferred embodiments, which are intended to illustrate, not limit, the invention.
The drawings illustrate the design and utility of preferred embodiments of the present invention. It should be noted that the figures are not drawn to scale and that elements of similar structures or functions are represented by like reference numerals throughout the figures. In order to better appreciate how the above-recited and other advantages and objects of the present inventions are obtained, a more particular description of the present inventions briefly described above will be rendered by reference to specific embodiments thereof, which are illustrated in the accompanying drawings. Understanding that these drawings depict only typical embodiments of the invention and are not therefore to be considered limiting of its scope, the invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:
The beveled end 112 of the proximal probe shaft portion 102 and the beveled end 114 of the distal probe shaft portion 102 engage in a manner that allows the shafts portions 104, 106 to be placed in an axially aligned relationship at the interface (i.e., the longitudinal axes 182, 180 are coextensive with each other at the interface) (see
In the illustrated embodiment, the probe 100 has an actuator for rotating the distal shaft portion 106 relative to the proximal shaft portion 104. In particular, the probe 100 includes a rod 140 disposed coaxially within the lumen 118 of the proximal shaft portion 104. The rod 140 includes a proximal end 142 secured to a handle 170, a distal end 144 coupled to the proximal end 114 of the distal portion 106 of the probe shaft 102, and a lumen 146 extending between the proximal and distal ends 142, 144. During use, the handle 170 can be torqued to rotate the rod 140, which causes the distal shaft portion 106 to rotate relative to the proximal portion 104 of the probe shaft 102. The handle 170 is preferably composed of a durable and rigid material, such as medical grade plastic, and is ergonomically molded to allow a physician to more easily manipulate the distal shaft portion 106. Thus, rotation of the handle 170 causes the rod 140, and thus the distal shaft portion 106, to rotate relative to the proximal shaft portion 104.
In the illustrated embodiment, the distal end 144 of the rod 140 is secured to the distal shaft portion 106 by a connector 150. The connector 150 includes a lumen 152 for housing a drive shaft 160. The connector 150 is made from an elastic material, such as plastic, rubber, aluminum, or other metals or alloys, such that the connector 150 can undergo deformation as the distal shaft portion 106 is being rotated relative to the proximal portion 104 of the probe shaft 102. In other embodiments, the connector 150 can be a spring, or have other configurations. A compression spring 172 is disposed between the proximal end 110 of the proximal shaft portion 104 and the handle 170, and is configured to exert a force that tends to separate the handle 170 axially away from the proximal end 110. Such feature allows the compression spring 172 to pull the rod 140 proximally relative to the proximal shaft portion 104, thereby ensuring that the proximal end 114 of the distal shaft portion 106 maintains contact with the distal end 112 of the proximal shaft portion 104 as the distal shaft portion 106 is being rotated relative to the proximal shaft portion 104. In other embodiments, instead of using the compression spring 172, the probe 100 can include other devices, mechanisms, or materials that pull the rod 140 proximally relative to the proximal shaft portion 104. Also, in other embodiments, the probe 100 does not include the compression spring 172. In such cases, an operator of the probe 100 can pull the handle 170 relative to the proximal shaft portion 104 of the sheath 102 to keep the proximal tip 132 in contact with the distal tip 134 during use.
The drive shaft 160 is disposed coaxially within the lumen 146 of the rod 140. The drive shaft 160 has a proximal end 162 secured to a driver 168, and a distal end 164 secured to a tissue removal element 166. The driver 168 may take the form of a standard rotary drive used for powering medical cutting instruments. In the illustrated embodiments, the driver 168 is secured to a proximal end of the handle 170. In alternative embodiments, the driver 168 can be secured to other locations on the handle 170, or can be a separate unit from the handle 170. During use, the driver 168 is activated to rotate the drive shaft 160, which in turn, causes the tissue removal element 166 to rotate. The tissue removal element 166 extends at least partially out of an opening 130 (a cutting window) located at a side wall of the distal shaft portion 106. The cutting window 130 exposes a portion of the tissue removal element 166, such that the tissue removal element 166 cuts and abrades tissue only on one lateral side (top) of the tissue removal probe 100, while protecting tissue at the opposite lateral side (bottom) of the tissue removal probe 100. In the illustrated embodiments, the cutting window 130 has a rectangular shape, but can have other shapes as well. In the illustrated embodiments, drive shaft 160 is made of a flexible material, such as coiled or braided stainless steel. In other embodiments, the drive shaft 160 can be made from other materials. In the illustrated embodiments, the distal end of the drive shaft 160 extends to the tissue removal element 166. Alternatively, the distal end of the drive shaft 160 extends through the tissue removal element, and is rotatably secured to a wall 190 at the distal end 116 of the distal shaft portion 106.
In some embodiments, the drive shaft 160 can be made slidable relative to the distal shaft portion 106, thereby allowing the tissue removal element 166 to be positioned axially relative to and within the cutting window 130. As can be appreciated, longitudinal movement of the drive shaft 160 slides the tissue removal element 166 along the cutting window 130 between a proximal position and a distal position. As such, the cutting window 130 advantageously limits the tissue removed to that which extends along the cutting window 130. At the same time, the length of the cutting window 130 allows a length of tissue to be removed without having to move the probe shaft 102. The length of the cutting window 130 will depend upon the length of the tissue that is to be removed. In the illustrated embodiment, the length of the cutting window 130 is in the range of 0.25-1.5 inches.
To facilitate placement and maintenance of the cutting window 130 at the tissue removal site, the distal and proximal portions 106, 104 of the probe shaft 102 are preferably rigid (e.g., it can be composed of a rigid material, or reinforced with a coating or a coil to control the amount of flexing), so that the probe shaft 102 provides a more stable platform from which to remove tissue. The probe shaft 102 can be made from a variety of materials, such as polymers, plastics, stainless steel, aluminum, or other metals or alloys. The materials used in constructing the probe shaft 102 may also comprise any of a wide variety of biocompatible materials. In some embodiments, a radiopaque material, such as metal (e.g., stainless steel, titanium alloys, or cobalt alloys) or a polymer (e.g., ultra high molecular weight polyethylene) may be used, as is well known in the art. In the illustrated embodiments, the probe shaft 102 has a cross sectional shape that is circular. Alternatively, the probe shaft 102 can have other cross sectional shapes. The outer cross sectional dimension of the probe shaft 102 is preferably less than ½ inch, but other dimensions for the outer cross sectional dimension of the probe shaft 102 may also be appropriate, depending on the particular application or clinical procedure. The lumen 118 of the proximal portion of the probe shaft 102 should have a cross sectional dimension so as to allow the rod 140 to be rotatably housed therein.
In the illustrated embodiments, the tissue removal element 166 is a burr that includes abrasive particles, such as diamond dust, disposed on a surface of the burr. In other embodiments, instead of, or in addition to, having diamond dust, parts of the surface of the burr can be removed to create an abrasive surface. The burr can also include one or more grooves formed along the surface of the burr. In such case, the groove(s) allows bone particles that have been removed to travel proximally and away from a target site. The burr is preferably made from a tough material, such as steel or other alloys, so that it could penetrate or cut into bone tissue without being damaged. In the illustrated embodiments, the tissue removal element 166 has an elliptical profile. Alternatively, the tissue removal element 166 can have other shapes, such as a spherical shape or a cylindrical shape.
In the illustrated embodiment, the distal end 112 of the proximal shaft portion 104 includes a first flange 206 defining a circular opening 207. The connector 202 includes a shaft 208 that extends through the circular opening 207, and a second flange 204 secured to the shaft 208. The flanges 204, 206 secure the distal shaft portion 106 to the proximal portion 104 of the probe shaft 102, and prevents the distal shaft portion 106 from separating from the proximal shaft portion 104 as the distal shaft portion 106 is being rotated relative to the proximal shaft portion 104. In this embodiment, the compression spring 172 is not necessary because the connector 202 functions to keep the distal and the proximal portions 106, 104 of the probe shaft 102 in contact during use. Alternatively, the probe 200 can include the compression spring 172 for maintaining the connector 150 in tension during use. In the illustrated embodiment, the connector 150 secures the distal end 144 of the rod 140 to the connector 202. The connector 150 undergoes deformation as the distal shaft portion 106 is being rotated relative to the proximal shaft portion 104.
In other embodiments, instead of having the connector 202 be associated with the distal shaft portion 106, the connector 202 can be associated with the proximal portion 104 of the probe shaft 102. In such cases, the proximal end 114 of the distal shaft portion 106 includes a first flange defining a circular opening, and the distal end 112 of the proximal shaft portion 104 includes the connector 202. It should be noted that the connector 202 is not limited to the configuration illustrated previously, and that the connector 202 can have other configurations in alternative embodiments.
In the above described embodiments, the distal probe shaft portion 104 is rotatably coupled to the proximal probe shaft portion 102. That is, the interface between the respective shaft portions 102, 104 allows the distal probe shaft portion 104 to rotate about or around the longitudinal axis 182 of the proximal probe shaft portion 102. The probe shaft portions, however, can be coupled in other manners in order to alternately place them in axially aligned and non-aligned relationships.
For example,
The probe 300 further includes an actuator for rotating the distal shaft portion 104 relative to the proximal shaft portion 102. In particular, the probe 300 includes a first and second wires 310, 312 that are counterwound around the hinge pin 302. That is, the first wire 310 wraps around the circumference of the hinge pin 302 in a first direction, and the second wire 312 wraps around the circumference of the hinge pin 302 in a second opposite direction. The distal tips (not shown) of the wires 310, 312 are secured to the hinge pin 302 using a suitable means, such as welding or soldering. During use, either of the wires 310, 312 can be selectively pulled to rotate the hinge pin 302, thereby causing the distal shaft portion 106 to hinge relative to the proximal shaft portion 104. For example, the first wire 310 can be pulled in a direction 320 to rotate the hinge pin 302 in a first direction 322. The rotation of the hinge pin 302, in turn, hinges the distal shaft portion 106 relative to the proximal shaft portion 104 in a direction, as indicated by arrow 324, to place the proximal and distal shaft portions 104, 106 from their axially aligned relationship (
It should be appreciated that providing a probe shaft having rigid distal and proximal portions that are rotatably coupled prevents or at least reduces the risk of the tissue removal probe unbending itself, thereby allowing the tissue removal probe to substantially maintain its bent shape during use. Although several embodiments of a tissue removal probe have been described, it should be noted that the tissue removal probe should not be limited to the configurations described previously, and that the tissue removal probe can have other configurations in alternative embodiments as long as a distal portion of the probe can be rotated relative to a proximal portion to form a bent profile during use.
Also, in other embodiments, any of the embodiments of the tissue removal probe described herein can optionally have irrigation and/or aspiration capability. For example, the tissue removal probe 100 can include an irrigation tube and/or an aspiration tube disposed in the lumen 146 of the rod 140. The irrigation tube terminates at an irrigation outlet port in the distal end 116 and proximally terminates at an irrigation inlet port in a proximal adapter. Likewise, the aspiration tube terminates at an aspiration entry port in the distal end 116 and proximally terminates at an aspiration outlet port in the proximal adapter. As can be appreciated, a pump (not shown) can be connected to the irrigation inlet port on the proximal adapter in order to flush irrigation fluid, such as saline, through the irrigation tube and out the irrigation outlet port. The irrigation fluid helps cool the drive shaft and/or the tissue removal element, while the tissue removal element is rotating at high speed and grinding against tissue. The media also washes away debris at the target site and tissue removal element. A vacuum (not shown) can be connected to the aspiration outlet port on the proximal adapter in order to aspirate the removed tissue into the aspiration inlet port, through the aspiration tube, and out of the aspiration outlet port. Because there are separate irrigation and aspiration tubes, both the pump and aspirator can be activated simultaneously or separately.
In the embodiments described previously, the drive shaft 160 is flexible along its entire length, such that the drive shaft 160 can be bent along with the probe as a distal portion of the tube is rotated to form a bent configuration with a proximal portion of the tube. In alternative embodiments, the drive shaft 160 can have other configurations. For example,
Although the tissue removal probe has been described as having the cutting window 130, in alternative embodiments, the cutting window 130 is optional, and the tissue removal probe does not include the cutting window 130.
Although the tissue removal element 166 has been described as a burr, the scope of the invention should not be so limited. Alternatively, the tissue removal element 166 can have a variety of shapes, sizes, and configurations, so long as the tissue removal element is capable of cutting, deforming, and/or abrading a target bone tissue. In some embodiments, a cutting basket 620 (
In other embodiments, the tissue removal element can be a drill bit 630 (
Any of the embodiments of the tissue removal probes described herein can further include an actuator for positioning the distal portion of the probe. For example,
Having described the structure of various embodiments of a tissue removal probe, its operation will now be described with reference to
First, a cannula 710 is introduced through a small incision 700 in the back 702 of a patient and into a herniated disc 704 situated between a top vertebra 730 and a bottom vertebra 732 (
Next, the tissue removal probe 100 is introduced through the cannula lumen until the distal portion 106 of the probe shaft 102 is at least partially out of the cannula lumen (
Next, the driver 168 is activated to rotate the tissue removal element 166, which cuts and/or abrades disc tissue with which it comes in contact. The proximal shaft portion 104 can be advanced distally or retracted proximally to position the distal end 106 axially. The proximal shaft portion 104 can also be rotated about the longitudinal axis 182 to face the cutting window 130 in a different radial position such that the tissue removal element 166 can cut and/or abrade different tissue at the disc 704. Depending on a size of the cannula lumen, the tissue removal probe 100 can also be positioned (e.g., tilted or translated) within the confinement of the cannula lumen to place the tissue removal element 166 at desired positions. It should be noted that, during the tissue removal procedure, the removed tissue can be aspirated from the herniated disc 704 using an aspirator. Aspiration of the tissue can be accomplished via the cannula or through another cannula. Alternatively, as previously described, aspiration can be accomplished via the tissue removal probe 100 itself if the irrigation tube and the aspiration tube are provided.
Due to the confinement by the cannula lumen, the tissue removal probe 100 only removes a portion 720 of the disc 704 along the axis of the cannula lumen (
If desired, the handle 170 can be rotated to bring the tissue removal probe 100 back to its rectilinear configuration. The proximal shaft portion 104 can then be rotated about the longitudinal axis 182 such that the cutting window 130 faces a different radial position. The handle 170 is then rotated again to provide the tissue removal probe 100 a bent configuration in a different direction (
After the discectomy has been completed (i.e., the herniated disc material has been removed, or in some cases, the entire herniated disc has been removed), the cannula 710, along with the tissue removal probe 110, is removed from the patient's body. Alternatively, prior to total removal of the cannula 710, the tissue removal probe 100 can be removed, and a therapeutic media, such as a drug or disc replacement material can be delivered through the cannula lumen into the disc 704.
Although particular embodiments of the present invention have been shown and described, it should be understood that the above discussion is not intended to limit the present invention to these embodiments. It will be obvious to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the present invention. In addition, an illustrated embodiment needs not have all the aspects or advantages of the invention shown. An aspect or an advantage described in conjunction with a particular embodiment of the present invention is not necessarily limited to that embodiment and can be practiced in any other embodiments of the present invention even if not so illustrated. Thus, the present invention is intended to cover alternatives, modifications, and equivalents that may fall within the spirit and scope of the present invention as defined by the claims.
