WO2016057576A1

WO2016057576A1 - Microfracturing instrument

Info

Publication number: WO2016057576A1
Application number: PCT/US2015/054326
Authority: WO
Inventors: Graham Smith
Original assignee: Smith & Nephew, Inc.
Priority date: 2014-10-06
Filing date: 2015-10-06
Publication date: 2016-04-14

Abstract

Embodiments of the invention include instruments for micro fracturing tissue by activating a vibration generator (10, 110) of a micro fracturing instrument (1, 100) and applying a tip (30, 130) of the micro fracturing instrument (1, 100) to tissue. In some embodiments, micro fracturing results from a combination of vibration of the instrument (1, 100) and an operator applying force to the instrument (1, 100) in a direction toward the tissue to be microfractured.

Description

MICROFRACTURING INSTRUMENT

RELATED APPLICATIONS

[0001] This patent application claims benefit of pending U.S. Prov. Pat. Appl. Ser. No. 62/060, 171, "Microfracturing Instrument and Method," filed October 6, 2014, which is hereby incorporated by reference herein.

FIELD OF THE INVENTION

[0002] The present invention relates generally to the field of medical devices, and more particularly relates to instruments and methods for microfracturing tissue. Some embodiments include a tip that is moved generally laterally relative to the surface of tissue being microfractured and has cutting features that are positioned to cut when moved in the generally lateral direction.

BACKGROUND

[0003] Defects in bone and tissues around bone may result from various circumstances or conditions. For example, tissue may be damaged, diseased, or simply worn or degraded as a result of repetitive motions. Excessive defects may result in the loss of full function of a joint, and ultimately even to the need for joint replacement. Repair treatments have been developed to restore some or even all of the function of a joint. In arthroscopy, one common method to repair defects, such as osteo-chondral defects, is to "microfracture" bone that is exposed in a defect. A surgeon may create relatively small fractures in a subchondral bone plate causing the release of multipotent mesenchymal stem cells from bone marrow. This procedure may lead to healing resulting from growth of repair tissue such as one or more of fibrous tissue, fibrocartilage, and hyaline-like cartilage.

[0004] Such a microfracture treatment is typically accomplished with a pointed awl or pick being applied directly to subchondral bone. In many cases, such as when microfractures are applied to an underside of a patella or in a hip, it is difficult to apply sufficient force to the tissue to be treated. Force typically has to be applied to the pointed awl or pick at a proximal location, which is usually distant from the distal point of impact with the tissue to be treated. The angles at which the pointed awl and pick are capable of receiving force effectively do not necessarily lead to the distal end of the pointed awl or pick making an accurate and effective tissue cut. For example, a pointed pick or awl may be driven into subchondral bone, either directly or indirectly by applying force with a hammer. This may lead to inaccurate and unsatisfactory microfracturing. In procedures where an instrument is passed through soft tissue to a deep joint, such as a hip joint, soft tissue may have a damping effect on the forces required to perform microfracturing. Therefore, an even greater force may have to be applied in such situations. Application of greater forces increases the risk of collateral damage to surrounding tissue.

[0005] It would be advantageous to provide methods and devices of creating microfractures that are more accurate, predictable, and repeatable. An improved device may require less aggressive application of force and result in more precise application of fracturing or cutting force than may result from such actions as striking an instrument with a hammer, for example. It may also be useful to apply cutting motion forces in only the directions or in more nearly the directions that are effective to cut tissue as needed to accomplish microfracturing.

SUMMARY

[0006] An embodiment of the invention is a microfracturing instrument with a vibration generator, a shaft, and a tip. The vibration generator may have a generally longitudinal axis, and the shaft may be coupled with the vibration generator and configured to be moved at the speed and direction of the vibrations of the vibration generator. The tip may be coupled to the shaft such that and the tip is configured to move at the speed and direction of the vibrations of the vibration generator and engage tissue to create microfractures in the tissue.

[0007] Another embodiment of the invention is a microfracturing instrument with a vibration generator, a shaft, and a tip. The vibration generator may have a generally longitudinal axis, and the shaft may be coupled with the vibration generator and configured to be moved at the speed and direction of the vibrations of the vibration generator. The tip may be fixedly coupled to the shaft and have one or more cutting elements of the tip used to create microfractures that are transverse to the longitudinal axis of the vibration generator [0008] Yet another embodiment of the invention is a method of microfracturing tissue. The method may include providing a microfracturing instrument that includes a vibration generator with a longitudinal axis, a shaft coupled with the vibration generator and configured to be moved at the speed and direction of the vibrations of the vibration generator, and a tip coupled to the shaft. The method may also include positioning the microfracturing instrument tip against a surface of the tissue to be microfractured and activating the vibration generator. The method may also include applying a force to the microfracturing instrument in the direction of the surface of the tissue to be microfractured, wherein unless the force is applied in the direction of the surface of the tissue to be microfractured, the tip would not substantially engage the tissue to microfracture the tissue.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] FIG. 1 is a perspective view of an embodiment of a microfracturing instrument.

[00010] FIG. 2 is a perspective view of the tip of the microfracturing instrument illustrated in FIG. 1.

[00011] FIG. 3 is a perspective view of the microfracturing instrument illustrated in FIG. 1 in use on a posterior patellar surface.

[00012] FIG. 4 is an enlarged perspective view of the distal end of the

microfracturing instrument illustrated in FIG. 3 in use on a posterior patellar surface. [00013] FIG. 5 is a perspective view of an embodiment of a microfracturing instrument.

DETAILED DESCRIPTION

[00014] A microfracturing instrument 1 and its components are illustrated collectively, separately, and in use in FIGS. 1-5. The microfracturing instrument 1 is shown in FIGS. 1 and 3 with a vibration generator 10, a shaft 20, and a tip 30. The vibration generator 10 shown has a generally longitudinal shape with a longitudinal axis lengthwise through the vibration generator 10. The vibration generator 10 depicted is configured to create vibration at its distal end 11 in a reciprocating motion substantially only along the longitudinal axis. Motion in one or both of this and other directions may be generated by vibration generators of other embodiments. In the illustrated embodiment, a power cord 12 is included to provide electrical energy to the vibration generator 10. In other embodiments, energy to drive an embodiment of a vibration generator may be supplied by any effective mechanism. For example and without limitation, an energy source may be one or more of a battery, pneumatic power, and hydraulic pressure. The frequency of vibration of various embodiments of a vibration generator may be any effective frequency, including ultrasonic frequencies and frequencies either lower or higher than ultrasonic frequencies.

[00015] The shaft 20 is depicted coupled with the vibration generator 10 and is configured to be moved at the speed and direction of the vibrations of the vibration generator 10. The illustrated shaft 20 includes a curve 21 (FIGS. 1 and 3) that may assist in effectively positioning the microfracturing instrument 1 in surgical procedures. In other embodiments, a shaft of the microfracturing instrument may include two or more curves, which may assist in more precisely positioning a microfracturing instrument to be more effectively used. The two or more curves may be in the same plane or may be in different planes. The two or more curves may be configured such that the tip of the microfracturing instrument is parallel with the longitudinal axis of the vibration generator or may be configured to create any other effective relative orientation between a vibration generator and a tip. One or more curves may essentially be bends with large radii relative to a diameter of a shaft or may be of any effective radii. A shaft of some embodiments may be substantially straight.

[00016] The tip 30 shown in FIGS. 1, 2, and 4 is coupled to the shaft 20 such that the tip 30 is configured to move at the speed and direction of the vibrations of the vibration generator and engage tissue to create microfractures in the tissue. As used herein, the term "tissue" may refer to bone, to tissue typically surrounding bone, or to other tissue. Bone tissue may include but is not limited to cortical bone and subchondral bone. Tissue typically surrounding bone may include but is not limited to fibrous tissue, fibrocartilage, and hyaline-like cartilage. The tip 30 may also be described as fixedly coupled to the shaft 20 in the illustrated embodiment. As used herein, the term "fixedly" means that the coupling does not provide for articulation, substantial flexing, or substantial relative movement between a shaft and a tip. This definition does not exclude typical yield, non-plastic deformation that may occur within a component or at the interface of two non-articulating connected components. In the embodiment depicted, a distal end of the tip 30 is not configured to move closer to and further from the shaft 20.

[00017] The illustrated tip 30 also includes an appendage 31 (FIGS. 1, 2, and 4) with a longitudinal axis that is transverse to the longitudinal axis of the vibration generator. In some embodiments, a vibration generator, shaft, and tip may be configured such that a longitudinal axis of the appendage is substantially

perpendicular to the longitudinal axis of the vibration generator. In some such configurations, the appendage may not be moved substantially along the longitudinal axis of the appendage by activation of the vibration generator. This lack of substantial movement along the longitudinal axis of the appendage does not exclude devices that are minimally moved by typical flexing of the shaft or by flexing of fixed couplings between one or more of the vibration generator, the shaft, and the tip. The appendage 31 illustrated is substantially the shape of a pyramid. In this embodiment, the pyramid is a square pyramid with four base edges, but in other embodiments may be a pyramid of any number of base edges greater than two. The appendage 31 shown is coupled to the rest of the tip 30 at the base of the pyramid, and the apex of the appendage 31 pyramid extends away from the rest of the tip 30 along the longitudinal axis of the appendage 31. The vertical edges 33 (FIG. 2) of the appendage 31 shown are transverse to the longitudinal axis of the vibration generator and serve as cutting elements of the tip 30, and may be used to create microfractures. Other embodiments of an appendage with a longitudinal axis transverse to the longitudinal axis of the vibration generator may include one or more cutting elements extending out from the longitudinal axis of the appendage of configurations that are different from the illustrated pyramid. For example and without limitation, an appendage may be a one or more sided blade, a hook, a round element with cutting elements, a polygon with edge cutting elements or other attached cutting elements, and a polygon that includes convex sides or concave sides (such as, for example, an appendage with the cross-sectional shape of a star). An appendage may also be a cone or other shaped component that in some respect has a relatively sharp portion that is effective as a cutting element.

[00018] Another embodiment of a microfracturing instrument is illustrated in FIG. 5. A microfracturing instrument 100 is shown in FIG. 5 with a vibration generator 1 10, a shaft 120, and a tip 130. The vibration generator 110 is essentially the same as the vibration generator 10, including all variations described above and will not be further described. The shaft 120 is essentially the same as the shaft 20, including all variations described above, and will not be further described.

[00019] The tip 130 shown in FIG. 5 is coupled to the shaft 120 such that the tip 130 is configured to move at the speed and direction of the vibrations of the vibration generator and engage tissue to create microfractures in the tissue. Stated another way, the tip 130 is fixedly coupled to the shaft 120 in the illustrated embodiment. As used here, the term "fixedly" means that the coupling does not provide for articulation, substantial flexing, or substantial relative movement between a shaft and a tip. This definition does not exclude typical yield, non-plastic deformation that may occur within a component or at the interface of two non-articulating connected components. In the embodiment depicted, a distal end of the tip 130 is not configured to move closer to and further from the shaft 120. The illustrated tip 130 includes a curette. The curette shown is a ring curette with one or more sharpened edges along peripheries of the ring. With this type of ring curette, tissue is removed by scraping a sharpened edge along tissue with the sharpened edge positioned transverse to the tissue. In other embodiments, a curette could be another type of curette, for example and without limitation, a ring curette or a cup curette. Other embodiments may include cutting or scraping instruments of any effective type at a tip of a

micro fracturing instrument. A segment of the illustrated ring curette with a sharpened edge may also be considered an appendage with a longitudinal axis that is transverse to the longitudinal axis of the vibration generator. In some embodiments, a vibration generator, shaft, and tip may be configured such that an axis passing through the segment and a sharpened edge are substantially perpendicular to the longitudinal axis of the vibration generator. In some such configurations, the segment with a sharpened edge may not be moved substantially along the axis of the segment with a sharpened edge by activation of the vibration generator. This lack of substantial movement along the axis of the segment with a sharpened edge does not exclude devices that are moved by typical flexing of the shaft or by flexing of fixed couplings between one or more of the vibration generator, shaft, and tip.

[00020] Some embodiments may include mechanisms for delivery of fluid to the area of the tip 30, 130. For example, fluid may be provided at least in part through one or both of the shaft 20, 120 and the tip 30, 130. Fluid may be provided through a conduit that runs alongside the instrument 1, 100 or by any other effective delivery structure. Suction structures may also be included in the shaft 20, 120, and tip 30, 130, and alongside the instrument 1, 100. An embodiment of the invention is a method of microfracturing tissue that includes the use of a microfracturing instrument with a vibration generator with a longitudinal axis, a shaft coupled with the vibration generator and configured to be moved at the speed and direction of the vibrations of the vibration generator, and a tip coupled to the shaft. Microfracturing instruments for use in the method may be essentially similar to the microfracturing instruments 1, 100 described in detail herein, along with any other effective variations. Other microfracturing instruments within the scope of the method described may also be used in carrying out the method. A method of use of a microfracturing instrument is illustrated in FIGS. 3 and 4. In the illustrated embodiment, the microfracturing instrument 1 is being used to treat tissue on the posterior side of a patella 50.

Methods of the invention may be applied to any other area of an anatomy where microfracturing of tissue may be efficacious for a patient. For example and without limitation, a method within the scope of the invention may be accomplished on articular surfaces of a hip joint or shoulder joint or at other locations within a knee joint.

[00021] In addition to providing a microfracturing instrument as described herein, method embodiments may include positioning the microfracturing instrument tip 30 against a surface of the tissue to be microfractured, as shown generally in FIG. 3 and in more detail in FIG. 4. More particularly in the embodiment shown, the appendage 31 (FIG. 2) is positioned against a surface of the tissue to be microfractured (FIG. 4). With the instrument tip 30 positioned, the method may further include activating the vibration generator 10. In the embodiment shown, activating the vibration generator 10 will cause the shaft 20 to be moved back and forth in the direction of the longitudinal axis of the vibration generator 10. Method embodiments may further include applying a force to the microfracturing instrument in the direction of the surface of the tissue to be microfractured. Longitudinal oscillations transmitted from the vibration generator 10, 110 to the microfracture tip 30, 130 cause cutting to occur at the tip 30, 130 when it is applied to a tissue surface. The force of application in the direction of the tissue surface is therefore greatly reduced over that required for current microfracture procedures. Also, if the vibrations are in the range of tens of kHz, soft tissue contacting the non-cutting portions of microfracture tip will not be affected because the soft tissue's elastic nature will absorb vibrational energy. As shown in FIGS. 1 and 3, the vibration generator 10 includes an exterior that may be gripped and to which a force may be applied and transferred to the tip 30 in the direction of the tissue surface through the shaft 20. The illustrated appendage 31 of the tip 30 with its pyramid shape would not substantially engage the tissue to microfracture the tissue when vibrated in the direction of the longitudinal axis of the vibration generator 10 without application of the force to the micro fracturing instrument toward the surface of the tissue. This is because the appendage 31 would not penetrate deeply enough into the tissue without a force being applied to the micro fracturing instrument and the direction of vibration would not significantly force the appendage 31 into the tissue to substantially engage the tissue. As used herein, the term "substantially engage" means to penetrate the tissue deeply enough to result in effective tissue microfracturing, ultimately leading to tissue healing. When a force is applied toward the surface, the apex of the appendage 31 is able to penetrate the tissue, and when the apex penetrates the tissue, the edges 33 (FIG. 2) are in a position to fracture the tissue further, leading to effective microfracturing. Similarly, with reference to FIG. 5, a sharpened edge of the curette embodiment of the tip 130 may require the application of a force in the direction of the surface of the tissue to be microfractured or otherwise treated to substantially engage the tissue to microfracture or otherwise treat the tissue.

[00022] Method embodiments may additionally include the act of applying a force to the microfracture instrument 1, 100 in the opposite direction from the surface of the tissue to be microfractured after a microfracturing in a first location has been accomplished. In other words, force applied in the opposite direction from the surface of the tissue to be microfractured disengages the tip 30, 130 from the tissue. The tip 30, 130 of the microfracturing instrument 1, 100 may then be repositioned at a separate location on the surface of the tissue to be microfractured and a force applied to the microfracturing instrument in the direction of the surface of the tissue to be microfractured in order to microfracture an additional portion of the surface of the tissue. This sequence may be repeated multiple times to microfracture a desired area.

[00023] Various embodiments of a system wholly or its components individually may be made from any biocompatible material. For example and without limitation, biocompatible materials may include in whole or in part: non-reinforced polymers, reinforced polymers, metals, ceramics, adhesives, reinforced adhesives, and combinations of these materials. Reinforcing of polymers may be accomplished with carbon, metal, or glass or any other effective material. Examples of biocompatible polymer materials include polyamide base resins, polyethylene, Ultra High Molecular Weight (UHMW) polyethylene, low density polyethylene, polymethylmethacrylate (PMMA), polyetheretherketone (PEEK), polyetherketoneketone (PEKK), a polymeric hydroxyethylmethacrylate (PHEMA), and polyurethane, any of which may be reinforced. Polymers used as bearing surfaces in particular may in whole or in part include one or more of cross-linked and highly cross-linked polyethylene. Example biocompatible metals include stainless steel and other steel alloys, cobalt chrome alloys, zirconium, oxidized zirconium, tantalum, titanium, titanium alloys, titanium- nickel alloys such as Nitinol and other superelastic or shape-memory metal alloys.

[00024] Terms such as distal, posterior, vertical, away, and the like have been used relatively herein. However, such terms are not limited to specific coordinate orientations, distances, or sizes, but are used to describe relative positions referencing particular embodiments. Such terms are not generally limiting to the scope of the claims made herein. Any embodiment or feature of any section, portion, or any other component shown or particularly described in relation to various embodiments of similar sections, portions, or components herein may be interchangeably applied to any other similar embodiment or feature shown or described herein.

[00025] While embodiments of the invention have been illustrated and described in detail in the disclosure, the disclosure is to be considered as illustrative and not restrictive in character. All changes and modifications that come within the spirit of the invention are to be considered within the scope of the disclosure.

Claims

Embodiments of the invention may include claims to:

1. A micro fracturing instrument comprising:

a vibration generator with a longitudinal axis;

a shaft coupled with the vibration generator and configured to be moved at the speed and direction of the vibrations of the vibration generator; and

a tip coupled to the shaft such that and the tip is configured to move at the speed and direction of the vibrations of the vibration generator and engage tissue to create microfractures in the tissue.

2. The micro fracturing instrument of claim 1 wherein the vibration generator vibrates at ultrasonic frequencies when being used to create microfractures.

3. The micro fracturing instrument of claim 1 wherein the vibration generator vibrates at frequencies below ultrasonic frequencies when being used to create microfractures.

4. The microfracturing instrument of claim 1 wherein vibrations created by the vibration generator are substantially only in the direction of the longitudinal axis of the vibration generator.

5. The microfracturing instrument of claim 1 wherein the shaft includes at least one curve.

6. The microfracturing instrument of claim 1 wherein the shaft includes at least two curves.

7. The microfracturing instrument of claim 1 wherein the tip includes an appendage with a longitudinal axis that is substantially perpendicular to the longitudinal axis of the vibration generator, and the appendage is not moved substantially along the longitudinal axis of the appendage by activation of the vibration generator.

8. The micro fracturing instrument of claim 1 wherein the tip includes an appendage with a longitudinal axis transverse to the longitudinal axis of the vibration generator and one or more cutting elements extending out from the longitudinal axis of the appendage.

9. The micro fracturing instrument of claim 8 wherein the appendage is substantially the shape of a pyramid.

10. The micro fracturing instrument of claim 1 wherein the tip includes a curette.

1 1. The micro fracturing instrument of claim 1 wherein the tip is fixedly coupled to the shaft and has one or more cutting elements that are used to create microfractures that are transverse to the longitudinal axis of the vibration generator.

12. A micro fracturing instrument of claim 1, further comprising a fluid delivery mechanism configured to deliver fluid near the tip of the microfracturing instrument.

13. A method of microfracturing tissue comprising:

providing a microfracturing instrument comprising:

a vibration generator with a longitudinal axis,

a shaft coupled with the vibration generator and configured to be moved at the speed and direction of the vibrations of the vibration generator, and a tip coupled to the shaft;

positioning the microfracturing instrument tip against a surface of the tissue to be microfractured;

activating the vibration generator; and

applying a force to the microfracturing instrument in the direction of the surface of the tissue to be microfractured, wherein unless the force is applied in the direction of the surface of the tissue to be microfractured, the tip would not substantially engage the tissue to microfracture the tissue.

14. The method of claim 13 wherein the act of providing a vibration generator includes providing a vibration generator that vibrates at ultrasonic frequencies when being used to create microfractures.

15. The method of claim 13 wherein the act of providing a vibration generator includes providing a vibration generator that vibrates substantially only in the direction of the longitudinal axis of the vibration generator.

16. The method of claim 13 wherein the act of providing a tip includes providing a tip with an appendage with a longitudinal axis transverse to the longitudinal axis of the vibration generator and one or more cutting elements extending out from the longitudinal axis of the appendage.

17. The method of claim 16 wherein the act of providing a tip with an appendage includes providing a tip that includes an appendage that is substantially the shape of a pyramid with an apex of the pyramid being directed away from the tip.

18. The method of claim 13 wherein the act of providing a tip includes providing a tip that includes a curette.

19. The method of claim 13, further comprising applying a force to the microfracturing instrument in the opposite direction from the surface of the tissue to be micro fractured, repositioning the tip of the microfracturing instrument at a separate location on the surface of the tissue to be micro fractured and applying a force to the microfracturing instrument in the direction of the surface of the tissue to be microfractured.