JP4067637B2 - Cement restrictor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a device used for hip arthroplasty, and more particularly to a structure that creates a restriction or occlusion in a bone against the inflow of cement.
[0002]
[Prior art]
When performing arthroplasty to replace the hip joint, the femoral head and neck must be removed, and then an artificial hip joint stem must be implanted in the femoral bone marrow canal. Some hip arthroplasties require the use of bone cement to secure the hip stem in the medullary canal. When using this cement, it is generally undesirable for the cement to invade the medullary canal to an uncontrollable depth and an uncontrollable amount. Therefore, in hip arthroplasty, a step of providing an obstacle in the medullary canal is provided in order to restrict or prevent the flow of cement.
[0003]
By the way, there are many cases where the obstacle is merely a ball-shaped cement that has been partially singulated or hardened, inserted into the bone marrow canal and brought into close contact by friction with the wall of the canal. Such timed obstacles are easily dislodged by the distal end of the hip stem if the cement ball is not inserted deep enough into the medullary canal. Furthermore, the cement balls move easily when pressurized cement is poured into the medullary canal to join the hip stem in place. If the cement ball breaks or enters the narrow midsection of the femur, known as the isthmus, the pressurized cement will not properly infiltrate the bone, creating air pockets and holes in the cement. Become. Such insufficient cement filling / individuation weakens the interlocking engagement of the bone and hip stem, and tends to crack. In addition, weak mechanical interlocks and cement defects can loosen the hip stem. When such an unfavorable situation occurs, the joint may need to be replaced by a procedure of repair (reconstruction).
[0004]
Repair procedures and procedures that require a “long” hip stem are particularly problematic for fillings that require the use of pressurized cement. In particular, the distal end of the repair stem eventually extends deeper into the medullary canal than the original “normal” stem. This is because the accompanying bone is cut during removal of the original stem in preparation for the implantation of the repair stem, or in the case of poor quality bone, it reaches high quality bone to stabilize the implant This is because a larger stem is used to fix the medullary canal further away. The distal end of the original stem extends only to a point just before or above the gorge (and thus above the cement ball), while the distal end of the repair stem extends beyond the gorge.
[0005]
Structures other than cement balls are also known for closing the inside of the medullary canal. For example, FIG. 1 shows a device 10 that includes a tapered body 12, which has a first end 14, a second end 16, and fins 18 that extend radially from the body 12. Each fin 18 has elasticity and can be bent toward the first end portion 14 or the second end portion 16 as indicated by a broken line in FIG. By applying pressure to one or more fins 18 or confining them in an enclosed space and elastically deforming them, these fins can be kept bent, but once the pressure is released or the device is When removed from the enclosed space, the fin 18 always returns to its original state as long as it is not plastically deformed. For this reason, in FIG. 1, it can be said that the fin 18 and the apparatus 10 have only one single stable state (single stable state).
[0006]
This single-stage stable device 10 is well suited for the purpose of closing the bored bone marrow canal 20 above the isthmus 22 as shown in FIG. It will be appreciated that the amount of deformation of the fin 18 varies depending on the location within the tapered bone marrow canal 20. The body 12 and the fins 18 are so thick that the device 10 remains wider than the gorge 12 even when the fins are fully pressed against the body so that the device 10 is not easily pushed over the gorge. To. Thus, in the typical case where pressurized cement is applied, pressing the cement does not disconnect the device.
[0007]
In contrast to the application above such a gorge, as shown in FIG. 3, the device 10 is completely unsuitable when applied across the gorge. In particular, when some of the fins 18 of the device 10 move beyond the isthmus, the strength of the mechanical interlock with the bone gradually decreases, and the device that becomes a plug will come off even if a slight pressure is applied. Even if the device 10 is carefully passed through the isthmus and then pulled back toward a narrow passage, as shown in FIG. 4, the deflected fins 18 bias the device away from the isthmus. Will.
[0008]
[Problems to be solved by the invention]
An object of the present invention is to provide a cement restrictor (cement restricting device) particularly suitable for repair joint arthroplasty by overcoming the drawbacks of the above-described known techniques and devices. It is an object of the present invention to provide a cement restrictor that can be a fixed obstacle even at an arbitrarily selected position inside a long bone, particularly beyond the isthmus, if it has an appropriate size.
[0008]
[Problems to be solved by the invention]
It is an object of the present invention to overcome the drawbacks of known techniques and devices and to provide a cement restrictor that is particularly suitable for repair arthroplasty. A properly sized cement limiter creates an obstruction that is fixed anywhere within the long bone, especially at points beyond the isthmus.
[0009]
[Means for Solving the Problems]
The cement restrictor according to the present invention includes a first shape having a first diameter with respect to a selected axis, and a second shape having a second diameter larger than the first diameter with respect to the selected axis. A deformable structure having a shape of 2;
[0010]
The cement restrictor of the present invention may be a kit further including a sleeve that can surround at least a part of the deformable structure, or an inflatable body.
[0011]
In other embodiments, the cement restrictor is made from a shape memory alloy that returns shape or size in response to temperature and / or stress.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
The invention and its advantages and constructions will be better understood from the following detailed description with reference to the accompanying drawings.
[0013]
5 and 6 are a side view and a perspective view, respectively, of the cement restrictor 24 according to one aspect of the present invention. In the cement restrictor 24, one or more fins 28 extend radially from the body 26 in a first stable state. As used herein, “stable state” means that a structure (eg, fin) maintains a predetermined shape, arrangement, or orientation with respect to another element (eg, main body), and the structure is within a predetermined range. Even if deformed, if there is no additional or external force or energy, the structure returns to a predetermined shape and arrangement. As will be described in detail below, the fins 28 can be deformed by applying pressure in the first direction, and return to the original orientation prior to deformation by interrupting the pressurization. On the other hand, when pressure is applied to the fins 28 in the second direction, the fins are deformed so as not to return to the pre-deformation orientation after the pressure is removed.
[0014]
5 and 6, the longitudinal body 26 has a first end portion 30, a second end portion 32, and an intermediate portion 34 between the both end portions. The fins 28 may have the same size, but the fins 28 illustrated in the drawings have different diameters. For example, the fin 28 in the vicinity of the first end of the main body has the smallest diameter, and the fin 28 in the vicinity of the other second end has the largest diameter. The fins 28 that continue from the first end to the second end are larger than the front fins, respectively. Therefore, since the diameter of the main body 26 is uniform, the cement restrictor 24 has a tapered outline. The specific size of the fins and the overall contour of the cement restrictor 24 are determined according to the shape of the medullary canal wall at the location where the lesion is to be formed. In the case of a cement restrictor embodiment having fins 28 of different diameters but approximately the same thickness, the wide fins are more flexible than the narrow fins, so that the fins are of a predetermined size, such as a gorge with holes drilled. Allow enough deformation to fit through the hole. However, the gap between the fins 28 prevents the fins from being excessively deformed.
[0015]
The axial pressure applied to the body 26 toward the second end of the body, or the axial pressure applied to the fins toward the first end of the body, or a combination of these pressures is shown in FIG. Note that the fins 28 are deformed while the cement restrictor 24 remains in the first stable state. In contrast, the axial pressure applied to the body 26 toward the first end of the body, or the axial pressure applied to the fins toward the second end of the body, or a combination of these pressures 7 deforms the fins 28 to move the cement restrictor from the first stable state to the second stable state, as shown in FIG. When the cement restrictor is in the first stable state, the fins 28 are inclined toward the first end of the body or the fins facilitate the insertion of the cement restrictor into the medullary canal. In addition, it is noted that it is convex when viewed from the second end of the body. When in the second stable state shown in FIG. 7, the fins 28 are inclined towards the second end of the body, or the fins are cemented against the bone as shown in FIG. It is noted that it is concave as viewed from the second end of the body to prevent it from moving. In other words, the cement restrictor cannot transition from the second stable state to the first stable state. However, even in the second stable state, the fin can bend, and can return to a predetermined arrangement or shape indicating the second stable state, or can be biased to return.
[0016]
In the embodiment of the cement restrictor shown in FIGS. 5 to 7, eight fins 28 are provided. The number of fins depends on the mode and can be just one, but the surface of the mechanical interlock between the fin and bone is maximized so that the cement restrictor does not displace during the subsequent cement pressing process. In order to do so, it is desirable that the number of fins be large.
[0017]
In the illustrated embodiment, the fins 28 are formed from an elastic material such as polyethylene and are connected to or created integrally with the body 26 to be the two-stage stable type described above. However, the fins 28 can also be made from a temperature sensitive, pressure sensitive or super elastic shape memory alloy (SMA). In this case, the fin 28 is in the first stable state at the first temperature or the first stress condition, and is in the second stable state at the second temperature or the second stress condition. . In the illustrated embodiment, the cement restrictor is cooled below the body temperature (or heated above the body temperature) in the first stable state so that it can be easily inserted into the bone. Then, when the fin is warmed (or cooled) to the normal body temperature range, the fin transitions (transfers) to the second stable state and engages the bone. Furthermore, although the fins are shown here as discontinuous elements, they can also be a single spiral.
[0018]
Further, in FIGS. 5 and 6, the body 26 is at an engagement surface that can be operated with a surgical tool to place the cement restrictor and transition from the first stable state to the second stable state. It has a configuration. As shown, the body 26 has a recess required when a surgical tool 38 (shown in FIG. 10) can be inserted to push the cement restrictor 24 through the medullary canal, and when axial pressure is applied to the body. Or, it has a socket 36. The socket 36 has a resilient surface or sleeve to assist in temporarily holding the surgical tool 38 in engagement with the cement restrictor. In another embodiment, the socket 36 and surgical tool 38 are threaded. The particular configuration in the engagement of the surgical tool and its cement restrictor is not particularly important to the present invention.
[0019]
When in the second stable state, the fin 28 can hold the cement restrictor 24 in place in the bone, but with a roughened peripheral area, such as a surface adjacent to the fin edge. There is also an aspect. Furthermore, in another embodiment, such as in FIG. 8, barbs or catches 42 extend from the periphery of one or more fins. The cement restrictor can be twisted to cause the catch 42 to hook onto the bone. FIG. 9 illustrates another aspect of a cement restrictor configured to increase interlock with the bone surface. In this cement restrictor, notches 44 are provided in the radial direction in one or more fins. When the cement restrictor is twisted, the fins separate from each other at the incision and the edges of the fins bite into the bone.
[0020]
FIG. 10 shows the cement restrictor 24 according to an example of the present invention pushed into the medullary canal with the insertion tool 38. Note that the cement restrictor is in the first stable state and the fins 28 are deformed in the isthmus.
[0021]
In addition to the above aspects, the following can be expanded from a first diameter to a second diameter along a suitable axis and / or transitioned from a first stable configuration to a second stable configuration. In order to provide such a structure, a cement restrictor according to another embodiment that takes advantage of shape memory materials in addition to traditional materials such as metal wires will be described. Thanks to this ability to expand, the structure can pass through an opening or passage (eg, a medullary canal) in a small diameter state. And once it passes through an opening or passage (such as a canyon), the structure is expanded to a diameter larger than the diameter of the opening or passage. Such a structure has many uses, such as a plug, a cement restrictor, or an anchor, depending on the application.
[0022]
For example, FIG. 12 shows a shape memory material such as Nitinol that is rolled up or folded (and bordered as necessary) to provide a generally conical shaped structure 42 having a first diameter. 40 sheets are shown. When the stress on the folded structure is released or reduced, the cement restrictor 42 expands. The shape memory material can be folded in a special manner in the state shown in FIG. 12, but FIG. 14 shows that the sheet of shape memory material 44 is initially cramped to provide a cemented restrictor 46 having a small diameter. In addition, another embodiment will be described in which the cement restrictor having a larger diameter is expanded later. The shape memory material 44 may be cut or trimmed before being creased so that it takes on a specific shape when fully expanded, as shown in FIG. For example, the shape memory material 44 can be cut along the periphery of the cement restrictor 44 to provide a catch.
[0023]
FIG. 24 shows a sleeve or sheath 50 for constraining the cement restrictor 42 to a stressed state. When the sheath is removed from the cement restrictor 42, the cement restrictor expands as shown in FIG. In a typical example, a sheathed cement restrictor 42 is inserted into the bone marrow canal of the bone. In this case, the cement restrictor is held in place using a tool (not shown) in the position where the obstacle is to be created, and the sheath is removed. This expands the cement restrictor and creates a closure in the bone. Although the sheath or sleeve 50 is cylindrical in the figure, it can also be a band that surrounds only a portion of the cement restrictor 42.
[0024]
FIGS. 12 to 15, 24, and 25 show a mode in which first, under stress, the stress is released and then expanded. FIGS. 16 to 19 show a mode in which the shape is changed in response to a temperature change. For example, FIG. 16 shows a cylindrical structure 52 composed of a shape memory material. When heated as shown in FIG. 17, each portion of the structure 52 expands to various extents, resulting in a tapered structure. FIG. 18 shows a cylindrical structure 54 that transitions to an expanded stable state upon cooling. FIG. 19 shows a structure 54 within bone 56 that is partially covered with crushed ice.
[0025]
In yet another aspect, the cement restrictor is stable in an unconstrained state and transitions to the second state when stressed. For example, FIG. 20 shows a cylindrical cement restrictor 60 with a portion cut away to reveal a portion of the balloon catheter 62 in the space partitioned by the cement restrictor. When the balloon portion 64 of the balloon catheter 62 is inflated, at least a part of the cement restrictor is pushed outward as shown in FIG. When the balloon is deflated, the cement restrictor 60 remains expanded. In the case of a temperature responsive shape memory material, the balloon is filled with a heated or cooled fluid.
[0026]
26 to 29 show the internal structure element 66 of the cement restrictor shown in FIGS. The internal structural element 66 serves as a framework for forming a biocompatible material around it. The internal structural element 66 can be made of a shape memory material, but can also be made of a simple metal wire that can be deformed. As shown in FIG. 27, the balloon catheter 62 is in a space partitioned by a cement restrictor. When the balloon portion 64 of the catheter 62 is inflated, at least a part of the cement restrictor 66 is pushed outward as shown in FIG. When the balloon is deflated, the cement restrictor 60 remains expanded as shown in FIG.
[0027]
In yet another aspect, the structure 66 is not initially covered with a biocompatible material, but alone is placed inside the bone and expanded as shown in FIG. When the balloon is inflated, cement is poured over the structure 66 and allowed to harden. When the balloon is then deflated, the cement restrictor, which includes cement with wire reinforcement, remains in place in the bone. In this and other embodiments, a simple plug or cover (not shown) can be placed over the remaining openings partitioned by the cement restrictor. In order to prevent cement from adhering to the balloon, a shield (not shown) may be interposed between the coil and the balloon. Alternatively, there is a mode in which a non-adhesive coating is applied to the balloon.
[0028]
Another method of stressing a stress responsive or simply deformable cement restrictor is shown in FIG. This view shows the cement restrictor 68 engaged with the tool 70. The tool 70 is pressed or screwed into the cement restrictor to expand the cement restrictor as shown in FIG.
[0029]
FIG. 30 shows yet another embodiment of a cement restrictor that includes one or more wires 72 embedded in a biocompatible material 74 such as polyethylene. A wire 72 comprising a shape memory material or conventional copper, steel, etc. can be oriented in the axial direction of the cement restrictor as shown in FIG. When there is a change in temperature or stress (removal or application), at least a portion of the cement restrictor expands.
[0030]
FIGS. 32 through 35 show yet another embodiment of a cement restrictor with a tool 78. As shown in FIG. 32, the cement restrictor 76 has a groove through which one or more wires 80 are slidably passed. The tool 78 includes a slidable portion 82 that can be moved toward the cement restrictor 76 to slide the wire 80 within the groove and extend from the free end of the cement restrictor as shown in FIG. . The portion of the wire that is out of the groove can be in the form of a hook or hook 84 for engaging the bone. This hook 84 also serves to prevent the end of the wire from returning back into the groove. When the temperature changes, the cement restrictor 76 becomes expanded as shown in FIG. The tool 78 is then removed from the cement restrictor 76 (such as by twisting) as shown in FIG.
[0031]
Next, FIG. 36 shows a first state of the two-stage stable structure 86. FIG. 37 shows a second state of the two-stage stable structure 86. In order to provide a stable first and second state, a deformable wire 88 is embedded within the biocompatible material. If the wire 88 is a shape memory material, the state can be changed using an electric current in addition to the application of heat and stress. In some embodiments, a current of 250 mA is sufficient to activate the wire 88. Although only one two-stage stable structure 86 can be used as a cement restrictor, as shown in FIG. 38, two or more structures 86 are connected by a link 90 to connect the cement restrictor to the cement restrictor. You can also
[0032]
FIG. 39 shows a cement restrictor with two or more flexible biocompatible elements 92 connected to each other by one or more links 94. One or more wires 96 made of shape memory material engage each element 92. As shown in FIG. 39, the wire 96 is curved inwardly toward the longitudinal axis of the cement restrictor in a first state that pulls inwardly the outer portion of the element 92 engaged with the wire. As shown in FIG. 40, when the wire 96 is straight in the second state, the wire 96 no longer bends inward. When the wire is straight, the element 96 is pulled out with the wire and the cement restrictor is increased in diameter in the second state.
[0033]
In addition to embodiments that include shape memory elements that are sensitive to both stress and temperature in the single structure described above, FIGS. 41-43 show that the response temperature or transition temperature is within a single structure. Figure 3 shows a cement restrictor including a plurality of different temperature responsive elements. In particular, FIG. 41 shows a cement restrictor with a first portion 100 connected to a second portion 102 by a link element 104. In this restrictor, the size of the first part is constant, while the size of the second part and the link element changes. Although the figure shows a single second part and a linking element, additional elements that are substantially the same as the second part can be added to the structure via the linking element.
[0034]
In a typical embodiment, the first portion 100 includes a standard biocompatible metal, such as cobalt chrome, and the second portion 102 includes a UHMWPE composition having Nitinol wire 106 embedded therein. The link element 104 is a Nitinol wire. In this aspect, as with the above-described aspects, the “wire” should be understood to have a variety of cross-sectional shapes from rectangular, circular to irregular. The transition temperature of the wire 106 inside the second portion 102 is 98.5 ° F., but the link element 104 has a higher transition temperature of about 110 ° F. Since there is a difference in the transition temperature as described above, the cement restrictor can be deformed from the small diameter state shown in FIG. 41 to the large diameter state shown in FIG. And since the maximum transition temperature is 120 ° F., damage to the patient's tissue is avoided. As shown, the wire can extend beyond the end of the second portion, improving the strength of engagement with the bone.
[0035]
In use, the cement restrictor is deformed as follows. The first part 100 is placed at a position beyond the isthmus with the help of a tool (not shown) that can engage in a suitable recess 108 in the first part. The Nitinol wire in the second portion 102 changes in a straight line according to the patient's body temperature, and the diameter of the second portion is increased as shown in FIG. The UHMWPE composition of the second part has sufficient elasticity to straighten and change shape with the embedded Nitinol wire, while also having sufficient rigidity to withstand the pressing of the cement. A heat gun (not shown) with a long nozzle that blows heated air (above 99 ° F. and below 120 ° F.) is placed in the medullary canal near the first part. This heat activates the link element, shortens the length of the link element, and brings the horizontal second portion that is changing linearly closer to the first portion and into a narrower cross section of the isthmus. As a method other than the heat gun, there is a method of heating a wire with a current of about 1/4 A. This makes use of the fact that the resistance of the wire is proportional to the diameter of the wire (that is, for a wire having a diameter of 0.006 inches, a current having a resistance of 1 Ω / inch may flow). High frequency or ultrasound can also be used to activate the wire.
[0036]
Each aspect of the present invention shown and described so far is for illustrative purposes, but various changes, omissions, and additions may be made to the shape or details without departing from the spirit and scope of the present invention. Will.
[0037]
  Specific embodiments of the present invention are as follows.
A) Deformable having a first shape having a first diameter with respect to a selected axis and a second shape having a second diameter greater than the first diameter with respect to the selected axis. Cement restrictor with a simple structure.
  1) The deformable structure includes a shape memory materialEmbodiment A)Cement restrictor as described.
  2) The deformable structure has a sheet of shape memory material that is folded in the first shape and at least partially unfolded in the second shape.Embodiment A)Cement restrictor as described.
  3) In the first shape, the sheet of shape memory material is substantially conical, has a length in the axial direction, and has a diameter extending radially from this axis, but in the second shape, The cement restrictor according to embodiment 1), wherein the diameter becomes larger as the length becomes smaller.
[0038]
  4) The deformable structure has a peripheral edge with a catch.Embodiment A)Cement restrictor as described.
  5) The deformable structure is wrinkled in the first shape, and at least a portion is not wrinkled in the second shape.Embodiment A)Cement restrictor as described.
  6) The deformable structure has a first end along an axis and a second end opposite the first end, and when the structure is heated, the second end is The diameter is larger than the first end.Embodiment A)Cement restrictor as described.
  7) The deformable structure has a first end along an axis and a second end opposite the first end, and when the structure is cooled, the second end is The diameter is larger than the first end.Embodiment A)Cement restrictor as described.
[0039]
  8) The deformable structure has a first end along an axis and a second end opposite to the first end, and when the structure is stressed, the second end The part has a larger diameter than the first endEmbodiment A)Cement restrictor as described.
  9) The deformable structure includes a shape memory material embedded in a biocompatible materialEmbodiment A)Cement restrictor as described.
  10) The cement restrictor of embodiment 9), wherein the shape memory material is shaped into a longitudinal element.
  11) The cement restrictor of embodiment 10), wherein at least a portion of the longitudinal element extends from a portion of the biocompatible material.
[0040]
  12) The cement restrictor of embodiment 10), wherein the longitudinal element is a wire and is helical.
  13) The deformable structure comprises a cylindrical biocompatible body that encloses at least a portion of an element made from a helical shape memory material.Embodiment A)Cement restrictor as described.
  14) The deformable structure is a two-stage stable typeEmbodiment A)Cement restrictor as described.
  15) The deformable structure includes a plurality of two-stage stable structures linked together.Embodiment A)Cement restrictor as described.
[0041]
  16) A cement restrictor according to embodiment 15), wherein each said two-stage stable structure comprises a substantially planar body made of a biocompatible material enclosing an element comprising a shape memory material.
  17) The deformable structure includes a plurality of flexible biocompatible elements linked together with a two-stage stable elementEmbodiment A)Cement restrictor as described.
  18) The deformable structure has a first portion linked to the second portion by a link element, and the second portion changes from a shape having a first diameter to a shape having a second diameter. And including an element made of a shape memory material that can be deformed and activated at a first temperature that changes the shape of the second portion, and the link element further changes the shape of the link element. Made from shape memory material activated at a temperature of 2Embodiment A)Cement restrictor as described.
B) Deformable having a first shape having a first diameter with respect to a selected axis and a second shape having a second diameter greater than the first diameter with respect to the selected axis. A structure and
A cement restrictor kit comprising a sleeve capable of surrounding at least a portion of the deformable structure in the first shape.
C) a two-stage stable body having a first end and a second end and partitioning the air gap;
A cement restrictor kit comprising an inflatable body that can be stored in a gap partitioned by the body,
A cement restrictor kit in which the two-stage stable body transitions from a first stable state to a second stable state when the expandable body is expanded in the gap.
[0042]
【The invention's effect】
As described above, according to the present invention, at the time of hip arthroplasty, an optional position inside a long bone, particularly at a position beyond the isthmus, can be a fixed obstacle to the inflow of cement. A cement restrictor is provided.
[Brief description of the drawings]
FIG. 1 is a side view of a conventional cement restrictor.
2 is a cross-sectional view of a bored bone into which the cement restrictor of FIG. 1 has been inserted.
3 is a cross-sectional view of a pierced bone with the cement restrictor of FIG. 1 pushed over the bone isthmus. FIG.
FIG. 4 is a cross-sectional view of a pierced bone while the cement restrictor of FIG.
FIG. 5 is a side view of the cement restrictor according to one aspect of the present invention when in a first stable state.
6 is a perspective view of the cement restrictor of FIG. 5. FIG.
7 is a side view of the cement restrictor shown in FIGS. 5 and 6 in a second stable state. FIG.
FIG. 8 is a side view of a cement restrictor according to another aspect of the present invention when in a first stable state.
FIG. 9 is a perspective view of a cement restrictor according to still another aspect of the present invention when in a first stable state.
FIG. 10 is a schematic view when a cement restrictor in a first stable state is inserted into a part of a drilled bone.
FIG. 11 is a diagram showing an arrangement in which the cement restrictor of FIG.
FIG. 12 is a view showing a state when a cement restrictor according to another aspect of the present invention is in a first stable state.
13 is a view showing a state when the cement restrictor of FIG. 12 is in a second stable state. FIG.
FIG. 14 is a diagram showing a state when the cement restrictor according to another aspect of the present invention is in the first stable state.
15 is a view showing a state when the cement restrictor of FIG. 14 is in a second stable state. FIG.
FIG. 16 is a view showing a state when the cement restrictor according to another aspect of the present invention is in the first stable state.
17 is a view showing a state when the cement restrictor of FIG. 16 is in a second stable state. FIG.
FIG. 18 is a diagram showing a state when the cement restrictor according to another aspect of the present invention is in the first stable state.
FIG. 19 is a view showing a state where the cement restrictor of FIG. 18 is in a bone and shifts to a second stable state.
FIG. 20 is a view of a cement restrictor with a portion cut away to reveal the balloon catheter.
FIG. 21 shows the balloon of FIG. 20 inflated to move the cement restrictor from the first stable state to the second stable state.
FIG. 22 shows a cement restrictor and a tool for transitioning from a first stable state to a second stable state.
FIG. 23 shows the tool of FIG. 22 being used with a cement restrictor to transition from a first stable state to a second stable state.
FIG. 24 is a view showing a sheath used for maintaining the cement restrictor in a small diameter state.
25 shows a state where the diameter of the cement restrictor of FIG. 24 is increased.
FIG. 26 is a diagram showing an internal structure when the cement restrictor according to still another aspect of the present invention is in the first stable state.
27 shows a balloon catheter used with the cement restrictor of FIG. 26. FIG.
FIG. 28 shows the balloon of FIG. 27 inflated to move the cement restrictor from the first stable state to the second stable state.
29 shows the cement restrictor in a stable state expanded by the balloon of FIG. 27. FIG.
FIG. 30 is a diagram showing a state when the cement restrictor according to still another aspect of the present invention is in the first stable state.
FIG. 31 is a diagram showing a state when the cement restrictor of FIG. 30 is in the expanded second state.
FIG. 32 is a view showing a cement restrictor and a tool for expanding the cement restrictor according to still another aspect of the present invention.
33 shows a shape memory structure extending from one end of the cement restrictor of FIG. 32. FIG.
FIG. 34 is a diagram showing a shape memory structure in which the cement restrictor of FIG. 32 is expanded.
35 is a view showing a state where the cement restrictor of FIG. 32 is expanded and detached from the tool of FIG. 32.
FIG. 36 is a diagram illustrating a two-stage stable structure according to still another aspect of the present invention in a first state.
FIG. 37 is a diagram showing a state where the two-stage stable structure of FIG. 36 is in the second state.
FIG. 38 is a diagram showing several two-stage stable structures connected in a small diameter state.
FIG. 39 is a diagram showing several two-stage stable structures according to another embodiment, connected in a small diameter state.
40 is a view showing a state where the diameter of the two-stage stable structure of FIG. 39 is increased.
FIG. 41 is a view showing a state where a cement restrictor according to still another aspect of the present invention is in a state of a small diameter.
FIG. 42 is a diagram showing elements when the cement restrictor of FIG. 41 is in a first stage in a state of a large diameter.
43 is a diagram showing elements when the cement restrictor of FIG. 41 is in a second stage of a large diameter state. FIG.

Claims (7)

A cement restrictor that creates a cement restriction within the bone,
A first shape having a first diameter, and a second shape having a second diameter, with a fluid impermeable deformable structure,
The second diameter is larger than the first diameter,
The structure is inserted into the bone opening in the first shape;
The structure frictionally engages the bone opening in the second shape to form a fluid impermeable barrier in the bone opening;
The deformable structure includes a shape memory material that causes the deformable structure to transition to the second shape . The cement restrictor of claim 1, wherein the shape memory material is in the form of a sheet that is folded in the first shape and at least partially unfolded in the second shape. In the first shape, the sheet of shape memory material is substantially conical and has a length along a longitudinal axis and a diameter extending radially from the longitudinal axis;
  The cement restrictor according to claim 1, wherein in the second shape, the length is reduced and the diameter is increased. The cement restrictor of claim 1, wherein the deformable structure includes a perimeter with a catch. The deformable structure has a first end along the longitudinal axis and a second end located on the opposite side of the first end;
  The cement restrictor of claim 1, wherein when the deformable structure is stressed, the second end portion has a larger diameter than the first end portion. A cement restrictor that creates a cement restriction within the bone,
  A fluid impermeable deformable structure comprising a shape memory material;
  The deformable structure has a first shape having a first diameter and a second shape having a second diameter;
  The second diameter is larger than the first diameter,
  The structure is inserted into the bone opening in the first shape;
  The structure frictionally engages the bone opening in the second shape to form a fluid impermeable barrier in the bone opening;
  The deformable structure has a first end along the longitudinal axis and a second end located on the opposite side of the first end;
  The cement restrictor, wherein when the shape memory material is heated, the second end has a larger diameter than the first end. A cement restrictor that creates a cement restriction within the bone,
  A fluid impermeable deformable structure comprising a shape memory material;
  The deformable structure has a first shape having a first diameter and a second shape having a second diameter;
  The second diameter is larger than the first diameter,
  The structure is inserted into the bone opening in the first shape;
  The structure frictionally engages the bone opening in the second shape to form a fluid impermeable barrier in the bone opening;
  The deformable structure has a first end along the longitudinal axis and a second end located on the opposite side of the first end;
  The cement restrictor, wherein the second end portion has a larger diameter than the first end portion when the shape memory material is cooled.

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