Patent Application
20080243122
The invention relates generally to medical devices and procedures, and more particularly to medical devices and procedures for augmenting bone screws.
Bone screws are often used to stabilize bone structures within the body. For example, some known bone screws can be used as part of a fracture repair procedure. Known bone screws can also be used with other structural members, such as, for example, rods, bars and/or plates as part of a spinal fixation procedure. Such known bone screws, which are configured to be implanted into the vertebral pedicle, are often referred to as pedicle screws.
Once implanted into a host bone structure, some known bone screws can be susceptible to becoming “pulled out” from the host bone structure, loosened within the host bone structure and/or destabilized within the host bone structure. The susceptibility of a bone screw to pullout, loosening and/or destabilization can be compounded when the bone screw is implanted into soft portions of a bone structure (e.g., cancellous bone or diseased bone) and/or the bone screw is subjected to high loads. Accordingly, in certain situations bone cement can be used to augment the pull-out strength of known bone screws. The use of bone cement to augment a known bone screw, however, can be difficult and may not, in fact, increase the pull-out strength of the bone screw.
Thus, a need exists for improved apparatuses and methods for augmenting bone screws.
Apparatuses and methods for augmenting bone screws are described herein. In some embodiments, an apparatus includes an expandable member and a cutting member coupled to the expandable member. The expandable member is configured to form a cavity within a cancellous portion of a bone. The cutting member is configured to cut a cortical portion of the bone.
In some embodiments, an apparatus includes an expandable member and a cutting member coupled to the expandable member. The expandable member, which can be, for example, an inflatable member, is configured to form a cavity within a cancellous portion of a bone. The cutting member, which can be, for example, a whisk, a curette or the like, is configured to cut a cortical portion of the bone.
In some embodiments, an apparatus includes a first shaft, a second shaft, an expandable member and a cutting member coupled to the expandable member. The expandable member is configured to form a cavity within a cancellous portion of a bone. The cutting member is configured to cut a cortical portion of the bone. A portion of the second shaft is rotatably disposable within the first shaft. A portion of the cutting member is coupled to an outer surface of the second shaft such that the cutting member produces a cutting force on the cortical portion of the bone of when the second shaft is rotated within the first shaft and the cutting member is in contact with the cortical portion of the bone.
In some embodiments, a method includes forming a first cavity within a first portion of a bone. A second cavity is formed within a second portion of the bone, the first portion and the second portion being mutually exclusive. A material, such as for example, bone cement, is conveyed to the first cavity and the second cavity. A fixation device, such as for example, a pedicle screw, is inserted into the bone such that a first portion of the fixation device is disposed within the first cavity and in contact with the material, and a second portion of the fixation device is disposed within the second cavity and in contact with the material.
In some embodiments, a method includes forming a first cavity within a first portion of a bone by removing a portion of the first portion of the bone. A second cavity is formed within a second portion of the bone by compressing a portion of the second portion of the bone. The first portion of the bone and the second portion are mutually exclusive. In some embodiments, a shape of the second cavity is different than a shape of the first cavity. A material, such as for example, bone cement, is conveyed to the first cavity and the second cavity. A fixation device is inserted into the bone such that a first portion of the fixation device is disposed within the first cavity and in contact with the material, and a second portion of the fixation device is disposed within the second cavity and in contact with the material.
In some embodiments, an apparatus includes an anchoring member configured to limit the movement of a pedicle screw within a vertebra. A distal portion of the anchoring member has a size greater than a size of a proximal portion of the anchoring member.
In some embodiments, an apparatus includes an anchoring member configured to limit the movement of a pedicle screw within a vertebra. A distal portion of the anchoring member has a size greater than a size of a proximal portion of the anchoring member. The anchoring member has a first configuration in which a portion of the anchoring member is substantially liquid and a second configuration in which the portion of the anchoring member is substantially solid. The anchoring member is configured to limit the movement of the pedicle screw when in the second configuration.
In some embodiments, a kit includes a catheter and a cannula. The catheter has an expandable member and a cutting member disposed proximate to the expandable member. The expandable member is configured to form a cavity within a cancellous portion of a bone. The cutting member is configured to cut a cortical portion of the bone. The cannula, which is configured to receive a portion of the catheter, is configured be inserted percutaneously.
In some embodiments, an apparatus includes a portion of a cortical bone, a portion of a cancellous bone, an anchoring member and a fastener. The portion of the cortical bone defines a first cavity. The portion of a cancellous bone defines a second cavity that is displaced from the first cavity along a longitudinal axis. The anchoring member has a first portion and a second portion. The first portion of the anchoring member is disposed within the first cavity. The second portion of the anchoring member is disposed within the second cavity. The fastener is coupled to the anchoring member.
As used in this specification and the appended claims, the singular forms “a,” “an” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, the term “a member” is intended to mean a single member or a combination of members, “a material” is intended to mean one or more materials, or a combination thereof. Furthermore, the words “proximal” and “distal” refer to direction closer to and away from, respectively, an operator (e.g., surgeon, physician, nurse, technician, etc.) who would insert the medical device into the patient, with the tip-end (i.e., distal end) of the device inserted inside a patient's body first. Thus, for example, the end of the expandable member first inserted inside the patient's body would be the distal end of the expandable member, while the end of the expandable member to last enter the patient's body would be the proximal end of the expandable member.
The illustrated method then includes forming a first cavity within a first portion of the bone structure at 184. Similarly, the method includes forming a second cavity within a second portion of the bone structure at 186. The first portion of the bone structure and the second portion of the bone structure are mutually exclusive. Referring to
Returning to the flow chart shown in
Returning to the flow chart shown in
In this manner, the fixation device 150 can be augmented within the bone structure 10 by the material 146. Said another way, in some embodiments, the material 146 can correspond to the shape of and anchor within the first cavity 152 and/or the second cavity 154 to increase the strength of the fixation device 150 within the bone structure 10. Moreover, because the material 146 is in contact with mutually exclusive portions of the fixation device 150 (e.g., the first portion 152 and the second portion 154), the fixation device 150 can be augmented differently by the material 146 within the first cavity 152 and the material 146 within the second cavity 154. In some embodiments, for example, the material 146, the first cavity 152 and/or the second cavity 154 can be configured to increase the pull-out strength of the fixation device when disposed within the bone structure 10 (e.g., to increase the resistance of the fixation device 150 from being moved along its longitudinal axis AL). In other embodiments, the material 146, the first cavity 152 and/or the second cavity 154 can be configured to increase the resistance of the fixation device 150 to being rotated about its longitudinal axis AL and/or any other axis defined by the fixation device 150 when disposed within the bone structure 10. In yet other embodiments, the material 146, the first cavity 152 and/or the second cavity 154 can be configured to reduce the likelihood of the fixation device 150 loosening and/or becoming destabilized when disposed within the bone structure 10.
In some embodiments, the first portion 12 of the bone structure 10 can have different characteristics than the second portion 14 of the bone structure 10. For example, in some embodiments, the first portion 12 of the bone structure 10 can be a hard, dense structure, such as cortical bone, and the second portion 14 of the bone structure can be a softer, less dense structure, such as cancellous bone. Accordingly, in some embodiments, the first cavity 130 can be configured to augment the fixation device 150 in a certain way (i.e., to increase its resistance to rotation about the longitudinal axis AL) and the second cavity 134 can be configured to augment the fixation device 152 in another way (i.e., to increase its resistance to linear movement along the longitudinal axis AL).
Similarly, because of the different characteristics of the first portion 12 of the bone structure 10 and the second portion 14 of the bone structure 10, in some embodiments, the first cavity 130 can be formed by different methods than the second cavity 134. For example, in some embodiments, the first cavity 130 can be formed by removing a portion of the first portion 12 of the bone structure 10 and the second cavity 134 can be formed by compressing a portion of the second portion 14 of the bone structure 10.
Although the first cavity 130 and the second cavity 134 are shown as having similar sizes and/or shapes, in some embodiments, the first cavity 130 and the second cavity 134 can have different sizes and/or shapes. In this manner, the shape and/or size of the cavities can be configured to ensure that the fixation device is augmented as desired. For example,
As shown in
As shown in
In use, the expandable member 310 and the cutting member 320 can be deployed within a patient's body substantially simultaneously. The second shaft 306 can be moved along its longitudinal axis AL, as indicated by arrow B, within the first shaft 304 such that the expandable member 310 and the cutting member 320 can be positioned as desired within a bone structure 10. The bone structure 10 can be, for example, a vertebra. In some embodiments, as described above, the second shaft 306 can be positioned such that the cutting member 320 is positioned within a first portion 12 of the bone structure 10 and the expandable member 310 is positioned within a second portion 14 of the bone structure 10.
Once positioned within the bone structure 10, the cutting member 320 can be actuated by rotating the second shaft 306 with respect to the bone structure 10. In this manner, the cutting member 320 can produce a cutting force on the first portion 12 of the bone structure 10, thereby removing a portion of the first portion 12 of the bone structure 10 to form a first cavity 330, as described above. For example, in some embodiments, the first shaft 304 remains stationary with respect to the bone structure 10 and the second shaft 306 is rotated within the first shaft 304, as indicated by arrow C. The expandable member 310 can then be expanded within the second portion 14 of the bone structure 10, thereby compressing and/or displacing a portion of the second portion 14 of the bone structure 10 to form a second cavity 334, as described above. In this manner, the cutting member 320 and the expandable member 310 can cooperatively form the first cavity 330 and the second cavity 334 without the catheter assembly 300 being removed during the time between the forming of the first cavity 330 and the second cavity 334.
Although the catheter assembly 300 is shown and described in
As described above, in use, the second shaft 506 can be moved along its longitudinal axis AL, as indicated by arrow E, within the first shaft 504 such that the expandable member 510 and the cutting member 520 can be positioned as desired within a bone structure (not shown in
Although the expandable members are shown and described above as being substantially spherical when in the expanded configuration, in other embodiments, the expandable member can have any suitable shape when in the expanded configuration. For example, in some embodiments, an expandable member can have a shape corresponding to the desired shape of the cavity to be formed by the expandable member. Such shapes can include cylindrical shapes, substantially uniform shapes, irregular shapes, asymmetrical shapes and/or any suitable combination of the shapes disclosed herein.
Similarly, although the first cavities, the second cavities and the anchoring members shown and described above have substantially uniform shapes, such as, for example, spheres or cylinders, in some embodiments, the first cavity, the second cavity and/or the anchoring member can have a shape that is non-uniform, irregular and/or asymmetrical. For example,
As shown in
Although the size S12 of the distal portion 636 of the second cavity 634 (and the corresponding size S16) is shown as being larger than the size S13 of the proximal portion 635 of the second cavity (and the corresponding size S17), in other embodiments, the size S12 and/or the size S16 can be smaller than the size S13 and/or the size S17. In yet other embodiments, the size S12 and/or the size S16 can be substantially equal to the size S13 and/or the size S17. Similarly, although the size S14 of the central portion 637 of the second cavity 634 (and the corresponding size S18) is shown as being smaller than either the size S12 or the size S13 (and the corresponding sizes S16 and S17), in some embodiments, the size S14 can larger than or equal to the size S12 and/or the size S13.
The second cavity 734 is defined by at least a portion of the inner portion 34 of the vertebral body 36 and is spaced apart from the first cavity 730 such that the first cavity 730 and the second cavity 734 are spaced apart and are not contiguous (i.e., the first cavity 730 and the second cavity 734 do not share a common boundary). The second cavity 734 includes a proximal portion 735 and a distal portion 736. The distal portion 736 of the second cavity 734 includes protruding regions 733 that extend radially from a longitudinal axis AL of the second cavity 734. As described above, the size and/or shape of the protruding regions 733 can be configured to increase the strength of an anchoring member 740 (see
As shown in
As shown in
Although the bone structures shown and described above define a first cavity and a second cavity, in some embodiments, a bone structure can define any number of cavities. Similarly, an anchoring member can include any number of portions corresponding to the cavities defined by the bone structure. For example,
Similar to the medical devices described above, and using methods similar to those described above, an augmentation material, such as a bone cement, can be conveyed into the first cavity 830, the second cavity 834 and the third cavity 837. A fixation device (not shown in
While various embodiments of the invention have been described above, it should be understood that they have been presented by way of example only, and not limitation. Where methods described above indicate certain events occurring in certain order, the ordering of certain events may be modified. Additionally, certain of the events may be performed concurrently in a parallel process when possible, as well as performed sequentially as described above. Thus, the breadth and scope of the invention should not be limited by any of the above-described embodiments. While the invention has been particularly shown and described with reference to specific embodiments thereof, it will be understood that various changes in form and details may be made.
For example, in some embodiments, the methods shown and described above include certain events that occur during the same surgical procedure. For example, in some embodiments, a method includes forming a first cavity, forming a second cavity, conveying a material to the first cavity and the second cavity, and inserting a fixation device, as described above, during the same surgical procedure.
Although the material used to augment the fixation device within the first cavity is shown and described as being the same material used to augment the fixation device within the second cavity, in some embodiments, a first material can be used to augment the fixation device within the first cavity and a second material, different than the first material, can be used to augment the fixation device within the second cavity. For example, in some embodiments, a first type of bone cement can be used within the first cavity and a second, different type of bone cement can be used in within the second cavity. Moreover, the augmentation material is not limited to bone cements, but can be any suitable compound, including bone growth enhancers or the like.
Although the fixation devices are shown and described as being substantially solid member, in other embodiments, a fixation device can include perforations or openings configured to receive a portion of the augmentation material to further increase the strength of the resulting anchoring member. In other embodiments, a fixation device can have a hollow portion configured to receive a portion of the augmentation material and/or any new bone growth therein.
Although the fixation devices are shown and described as including threads to provide recesses in which an augmentation material can flow when in a liquid state, in other embodiments, a fixation device can include any type of protrusion suitable for increasing the surface area of the fixation device and/or the area of contact between the fixation device and the augmentation material. In some embodiments, for example, the protrusions can be shaped to increase the pull-out strength of the anchoring member and/or increase the resistance of the fixation device to being rotated about its longitudinal axis. For example, a protrusion configured to increase the pull-out strength of the anchoring member can have a surface that extends radially from the fixation device and is substantially normal to the longitudinal axis of the fixation device (threads are one such example). In other embodiments, a protrusion configured to increase the resistance of the fixation device to being rotated about its longitudinal axis can have a surface that extends radially from the fixation device and is substantially normal to the longitudinal axis of the fixation device. In yet other embodiments, a protrusion configured to increase the resistance of the fixation device to being rotated normal to its longitudinal axis can have a surface that extends in any suitable direction from the fixation device.
Although the anchoring members shown and described above are characterized by longitudinal axis, in other embodiments an anchoring member can be curved in the longitudinal direction. Similarly, although the fixation devices are shown and described as being substantially linear, in some embodiments, a fixation device can have any suitable shape. For example, in some embodiments, a fixation device can have two discontinuous linear portions that form a “V” shape, an “X” shape or the like.
Although the fixation devices and/or anchoring members are shown and described above as having at least one end portion that extends from a bone structure after the fixation device and/or anchoring member has been disposed therein, in some embodiments, a fixation device and/or anchoring member can be disposed within a bone structure such that no portion of the fixation device and/or anchoring member extends from the bone structure. In other embodiments, a fixation device and/or anchoring member can be disposed within a bone structure such that the fixation device and/or anchoring member extends from two or more sides of the bone structure.
Although the catheter assembly is shown and described as being used by first actuating the cutting member to form the first cavity and followed by actuating the expandable member to form the second cavity, in some embodiments, a catheter assembly can be used by actuating the expandable member first, followed by actuating the cutting member. In other embodiments, a catheter assembly can be used by actuating the expandable member and the cutting member substantially simultaneously.
Similarly, although the methods shown and described above include conveying a material to a first cavity and a second cavity before disposing a fixation device within the first cavity and second cavity, in some embodiments, a method can include disposing a fixation device within the first cavity and second cavity, followed by conveying the material to the first cavity and the second cavity. In some embodiments, for example, the fixation device can be used to convey the material into the first cavity and/or the second cavity.
Although the methods are shown and described above as including removing the cavity-forming tool before conveying the material to the first cavity and/or the second cavity, in some embodiments, a method can include conveying the material to the first cavity and/or the second cavity without first removing the cavity-forming tool. In some embodiments, for example, the cavity-forming tool can include delivery lumen configured to convey the material to the first cavity and/or the second cavity.
Although the methods are shown and described above as including forming at least a first cavity and a second cavity using a cavity-forming tool that engages a portion of the bone structure to remove, displace and/or compress a portion of the bone structure, in some embodiments, a method can include forming a cavity within a bone structure using a cavity-forming tool that does not directly engage the portion of the bone structure in which the cavity is formed. For example, in some embodiments, a method can include forming a first cavity using a cavity-forming tool that removes a first portion of a bone structure. The method can then include forming a second cavity by conveying a viscous material into a second portion of the bone structure. The viscous material can be conveyed into the second portion of the bone structure at a pressure sufficient to compress and/or displace the second portion of the bone structure, thereby forming the second cavity. Moreover, the viscous material can any type of material formulated to augment a fixation device, as described above. Said another way, in some embodiments, a method can include forming a cavity and conveying a material into the cavity substantially simultaneously. Moreover, in some embodiments, a method can include forming a cavity and conveying a material into the cavity using a single tool.
Similarly, although the catheter assembly is shown and described as including a cutting member configured to form a first cavity and an expandable member configured to form a second cavity, in some embodiments, a catheter assembly can include two cutting members (e.g., a curette and a whisk) configured to form the first cavity and the second cavity. In other embodiments, a catheter assembly can include two expandable members configured to form the first cavity and the second cavity. In yet other embodiments, a catheter assembly can include a cutting member configured to form a first cavity and a delivery lumen configured to convey a material and form a second cavity, as described above.
Although various embodiments have been described as having particular features and/or combinations of components, other embodiments are possible having a combination of any features and/or components from any of embodiments as discussed above. For example, one such embodiment includes a catheter having a first cutting member that includes a metallic whisk, a second cutting member that includes a curette and an expandable member.
