HK1093881A - Systems and methods for treating vertebral bodies - Google Patents

Abstract

A filler instrument comprises a first chamber section having a first cross sectional area (615) and a second chamber section having a second cross sectional area (620) less than the first cross sectional area. The second chamber section communicates with the first chamber section. The first chamber section includes an inlet for receiving a material into the filler instrument, and the second chamber section includes an outlet for discharging the material from the filler instrument. A first plunger (705) is sized to pass through the first chamber section and not the second chamber section. A second plunger (755) is sized to pass through an interior bore of the first plunger and into the second chamber section. In use, the first plunger displaces material residing in the first chamber section through the second chamber section toward the outlet, and the second plunger displaces material residing in the second chamber section through the outlet.

Description

Systems and methods for treating vertebral bodies

The application is a divisional application of a patent application with the international application date of 2001, 7-13, and the international application number of PCT/US01/22145, and the international application date of 2003, 1-14, entering the Chinese national stage, and the national application number of 01812871.3.

RELATED APPLICATIONS

This application is a continuation-in-part of the pending U.S. patent application having application number 09/134323, filed on 14/8/1998, entitled system and method for placing material into bone. This application also claims priority from provisional application No. 60/218237, filed on 7/14/2000.

Technical Field

The present invention relates generally to methods of treating diseased bone in humans and other animals.

Background

It is known to use an expandable structure, known as a "balloon", in cancellous bone. For example, U.S. patents US4969888 and US5108404 disclose devices and methods for using expandable structures in cancellous bone, which may be used to fix fractures of human and animal bones or other osteoporotic and non-osteoporotic conditions.

As part of the process of fixing the fracture, bone cement or other therapeutic compound may be injected into the target bone to repair and/or augment the target bone. Some companies provide bone cement injection devices. These devices are similar to a household caulking gun. Generally, such injection devices are provided with a pistol-shaped body which supports a chamber containing bone cement. The adhesive is typically in two parts and must be mixed in a mixer and then delivered to the chamber for injection.

Once mixed, and before curing, the binder is in a fluid, flowing, viscous fluid state, similar to a syrup or a thick, thin, pasty wafer. The injection device is provided with a plunger that can be actuated by a manual trigger or screw mechanism for pushing viscous bone cement out of the front of the chamber through a suitable nozzle and into the bone for treatment.

Once injected into the target bone, the cement undergoes a curing cycle of approximately 6 to 8 minutes. While curing, the adhesive goes from a viscous fluid state to a putty-like viscous state, and finally is a hard rigid block.

Summary of The Invention

The present invention in all aspects provides better control of the injection of cement and other flowable fluids into bone. Moreover, the present invention facilitates the injection of highly viscous filling materials into bone, either into cavities formed within the bone or directly into the bone.

The features and advantages of the invention will become apparent from the following description, the accompanying drawings, and the appended claims.

Brief description of the drawings

FIG. 1 is a side view of a human spine;

FIG. 2 is a representative coronal view of a vertebral body of a human body, which is a detached portion and is a segment thereof, which is a portion of the spinal column shown in FIG. 1;

fig. 3 is a side view of several vertebral bodies which are portions which are missing and which are a segment thereof, which is part of the spinal column shown in fig. 1.

FIG. 4 is a schematic plan view of a tool having an expandable structure at a distal end thereof, the expandable structure being configured to compress cancellous bone in use, the structure being shown in a collapsed condition;

FIG. 5 is an enlarged side view of an expandable structure provided on the tool shown in FIG. 4;

FIG. 6 is a coronal view of the vertebral body of FIG. 2 with a tool of FIGS. 4 and 5 disposed through the posterolateral access in a collapsed condition;

FIG. 7 is a coronal view of the vertebral body and tool of FIG. 6, wherein the tool in an expanded state compresses cancellous bone and forms a cavity;

FIG. 8 is a coronal view of the vertebral bodies of FIGS. 6 and 7 with the tool extracted after the cavity has been formed;

FIG. 9A is a coronal view of the vertebral body of FIG. 8 with the cavity filled with material to reinforce the vertebral body;

FIG. 9B illustrates an alternative method of filling the cavity within the vertebral body;

FIG. 9C shows the vertebral body of FIG. 9B with the cavity filled approximately half as much material;

FIG. 9D illustrates the vertebral body of FIG. 9B with the cavity substantially filled with material;

FIGS. 10A through 10I are coronal views of a vertebral body showing the use of a tool that establishes a posterolateral access to compact cancellous bone within the vertebral body to form an interior cavity that can be filled with material to reinforce the vertebral body;

FIG. 11A is a side view of a tool for introducing material into a cavity formed in cancellous bone, with a nozzle having a stepped profile to reduce overall fluid resistance;

FIG. 11B is a side view of a tool for introducing material into a cavity formed in cancellous bone, with a nozzle having a tapered profile to reduce overall fluid resistance;

FIG. 11C is a side view of a tool for introducing material into a cavity formed in cancellous bone with a nozzle having an interior tapered profile to reduce overall fluid resistance;

FIG. 12 is an exploded perspective view of a cannula and material introduction device which may embody features of the invention;

FIG. 13A is a side cross-sectional view of one embodiment of a fill structure constructed in accordance with the teachings of the present invention;

FIG. 13B is a side view of the fill structure shown in FIG. 13A taken along line 13B-13B;

FIG. 14A is a side view of one embodiment of a first plunger assembly constructed in accordance with the teachings of the present invention;

14B and 14C are side views of the first plunger assembly shown in FIG. 14A;

FIG. 14D is a cross-sectional view taken along line 14D-14D of the first plunger assembly shown in FIG. 14C;

FIG. 15 is a side view of one embodiment of a second plunger assembly constructed in accordance with the teachings of the present invention;

FIGS. 16A to 16C are schematic views of a clamping assembly;

17A-17D are schematic illustrations of an alternative embodiment of a first plunger assembly constructed in accordance with the teachings of the present invention;

figure 18 is a side view of an alternate embodiment of a second plunger assembly constructed in accordance with the teachings of the present invention;

figures 19A through 19D are schematic illustrations of yet another alternative embodiment of a first plunger assembly and a filling structure constructed in accordance with the teachings of the present invention.

The embodiments of the present invention in several forms are described without departing from the spirit or essential characteristics thereof. The scope of the invention is indicated by the appended claims rather than by the foregoing detailed description. Therefore, all embodiments that come within the meaning and range of equivalency of the claims are to be embraced within their scope.

Detailed description of the preferred embodiments

The specification describes new systems and methods for treating bone. The use of expandable bodies for treating bone is substantially disclosed in U.S. patent nos. US4969888 and US5108404, the contents of which are incorporated herein by reference. Improvements in this regard are disclosed in U.S. patent application No. 08/188224 filed on a date of 26/1/1994; us patent No. 08/485394 filed on 7/6/1995; and U.S. patent No. 08/659678 filed on 1996, 6/5, which is incorporated herein by reference. It will also be appreciated that the new system and method can be used to treat bone without the use of an inflatable body if desired.

The novel systems and methods described are directed to treating vertebral bodies. It will be appreciated, however, that the systems and methods so described are not limited in their application to the spinal column only. The systems and methods can be used to treat various types of bone, including, but not limited to, radius, humerus, femur, tibia, or calcaneus.

I. Vertebral body

As shown in FIG. 1, the spinal column 10 includes a plurality of uniquely shaped bones called vertebrae 12, the sacrum 14, and the coccyx. The number of vertebrae 12 constituting the spinal column 10 varies depending on the kind of animal. In the human body (as shown in fig. 1), there are 24 vertebrae 12, including seven cervical vertebrae 18, twelve thoracic vertebrae 20, and five lumbar vertebrae 22.

As shown in FIG. 1, the spine 10 has an S-shaped curve if viewed from the side. This curve is used to support a heavy head. In quadrupeds, the curve of the spine is relatively simple.

As shown in fig. 1-3, each vertebra 12 includes a vertebral body 26 that extends on an anterior side (i.e., front or chest) of the vertebra 12. As shown in fig. 1-3, the vertebral body 26 is oval in shape. As shown in fig. 2 and 3, the vertebral body 26 includes an exterior formed of dense cortical bone 28. Cortical bone 28 encloses an interior volume 30 of cancellous or cartilage bone 32 (also known as medullary bone or small beam bone). Between the vertebral bodies 26 is a "shock pad" referred to as an intervertebral disc 34.

An opening, referred to as a vertebral foramen 36, is provided on the posterior (i.e., dorsal) side of each vertebra 12. The spinal ganglion 39 passes through the vertebral foramen 36. The spinal cord 38 passes through the spinal canal 37.

The vertebral arch 40 encircles the spinal canal 37. The pedicle 42 of the vertebral arch 40 is adjacent the vertebral body 26. The spinous process 44 extends posteriorly from the vertebral arch 40, as do the left and right transverse processes 46.

Treatment of vertebral bodies

A. From the side

The vertebral body may be accessed from many different directions depending on the target location within the vertebral body, the anatomy of the intervention, and the complexity required for the surgical procedure. For example, it may also be passed through the pedicle 42 (transpedicular), outside the pedicle (extrapedicular), along either side of the vertebral body (posterolateral), laterally or anteriorly into the body. In addition, this method can be used with closed, minimally invasive procedures or open procedures.

Fig. 4 illustrates a tool 48 for preventing or treating compression fracture or collapse of a vertebral body using an expandable body.

The tool 48 includes a catheter 50 having a proximal end 52 and a distal end 54, respectively. The distal end 54 carries a structure 56 having an expandable outer wall 58. The structure 56 shown in fig. 4 with the outer wall 58 is in a collapsed geometry. The structure 56 is shown in an expanded geometry in fig. 5.

The collapsed geometry allows the construct 56 to be inserted into the interior volume 30 of a targeted vertebral body 26, as shown in fig. 6. The structure 56 can be inserted into the interior volume 30 in a variety of ways. Fig. 6 illustrates a method of inserting a construct 56 through a lateral portal, the construct 56 extending through a lateral portion of the vertebral body 12.

For example, if a compression fracture causes the vertebral body 26 to subside below the plane of the pedicle 42, or for other reasons depending on the preference of the physician, it is accessed from the side. Either a closed, minimally invasive procedure or an open procedure may be used to access from the side. Of course, based on interventional dissection methods, one skilled in the art knows that lateral intervention is not an optimal access channel when treating vertebrae at all levels of the spine.

The catheter 50 includes an inner lumen 80 (see fig. 4). The lumen 80 is connected to a source of fluid pressure, such as saline, at the proximal end of the catheter 50. A syringe containing a fluid may include such a pressure source. The lumen 80 delivers fluid under pressure to the structure 56. The outer wall 58 then expands as shown in fig. 5 and 7.

The fluid is preferably radiopaque so as to facilitate visualization as it enters the interior of structure 56. For example, Renograffin can be used for this purpose^TM. Because the fluid is radiopaque, the expansion of the structure 56 can be monitored using fluoroscopic or CT visualization methods. With real-time MRI, the structure 56 may be filled with sterile water, saline solution, or sucrose solution, any radiopaque material. Other types of visualization methods may be employed as desired, employing reference markers in accordance with the tool 48. Alternatively, the structure may incorporate radiopaque material into the material of the structure itself, or the structure may be sprayed or wiped with radiopaque material.

Expansion of the outer wall 58 expands the structure 56, preferably compressing cancellous bone 32 (see fig. 7) within the interior volume 30 and/or causing a desired displacement of cortical bone. Compacting the cancellous bone 32 may form a cavity 60 within the interior volume 30 of the vertebral body 26 (see fig. 8). As will be described below, the filler material 62 may be safely and easily introduced into the cavity 60 formed by the compacted cancellous bone 32. In one embodiment, the expansion of the structure 56 preferably forms a region substantially surrounding the cavity 60 that compresses cancellous bone. This region preferably includes a physical barrier that limits leakage of the filler material 62 to the exterior of the vertebral body 26. In an alternative embodiment, expansion of the structure 56 preferably compresses cancellous bone 32 into the fractured portion of cortical bone, thereby reducing the likelihood of leakage of filler material 62 through the cortical wall. In another alternative embodiment, the expansion of the structure 56 preferably flattens veins in the vertebral body that pass through the cortical wall (e.g., vertebral body veins), thereby providing less opportunity for the filler material 62 to seep through the venous structure in the cortical wall to the exterior of the vertebral body.

Alternatively, expansion of the structure 56 will compact the less dense and/or functionally weaker regions of the cancellous bone, well enhancing the average density and/or overall strength of the remaining cancellous bone.

Compression of cancellous bone with the structure 56 may also exert an internal force on cortical bone. Alternatively, the structure 56 may directly contact cortical bone, thereby expanding and/or manipulating the structure 56 to create displacement of cortical bone. Thus, expansion of the construct within the vertebral body 26 may raise or push the fractured and compressed bone back to or near the original pre-fractured position.

The construct 56 is preferably left inflated within the vertebral body 26 and allowed to wait for a suitable period of time, such as three to five minutes, for some degree of clotting to occur within the vertebral body 26. After waiting a suitable period of time, the physician collapses the construct 56 and removes it. As shown in fig. 8, once the structure 56 is removed, the resulting cavity 60 is satisfactorily retained within the interior volume 30.

As shown in FIG. 9A, the physician next injects a filler material 62 into the formed cavity 60. The filler material may include a material that resists torsional, tensile, shear and/or compressive forces within the cavity 60 so that the renewed interior structure provided may support the bone cortex 28. For example, material 62 may include the following materials: bone cement, allograft tissue, autograft tissue or hydroxyapatite, synthetic bone substitutes, which are injected into the cavity 60 and set in time to a generally hardened condition. The material 62 may also include a pressure resistant material such as rubber, polyurethane, cyanoacrylate, or silicone rubber that is injected into the interior of the cavity 60. The material 62 may also comprise a semi-solid, pulpy material (e.g., bone slurry in a saline matrix) that is either contained within a porous fibrous structure disposed within the cavity 60 or injected directly into the cavity 60 to withstand the pressure within the cavity 60. Alternatively, the material 62 may include tension members, rebar, or other types of internal support structures that are well suited to withstand compressive, tensile, torsional, and/or shear forces exerted on the bone and/or filler material.

The filler material 62 may also include a drug, or a combination of a drug and a crush resistant material as described above.

Alternatively, the filler material 62 may comprise a bone filler material that is not capable of withstanding the pressure, tension, torsion, and/or shear forces within the cavity. For example, it is undesirable for the patient to experience significant forces within the spine immediately after surgery, such as when the patient is confined to bed rest or is wearing a brace, there is no need for the filler material 62 to be able to immediately bear the load. More preferably, the filler material 62 may provide a framework for bone growth, or may include a material that facilitates or accelerates bone growth, allowing the bone to heal over time. As another alternative, the filling material may include a resorbable or partially resorbable resource made of organic or inorganic materials for the treatment of various bone or related non-bone disorders, including, but not limited to, osteoporosis, cancer, degenerative disc disease, heart disease, Acquired Immune Deficiency Syndrome (AIDS), or diabetes. In such a method, the cavity and/or filling material may comprise a source of material to treat a condition located outside the treated bone.

In an alternative embodiment, the expandable material 56 may be retained in the cavity 60 after expansion. In this configuration, a flowable filler material 62 is delivered to the structure 56, and the structure 56 is operable to contain the material 62. The structure 56 filled with material 62 may be used to provide a renewed interior structure that supports cortical bone 28.

In this embodiment, the structure 56 may be made of an inert, durable, non-degradable plastic material, such as polyethylene and other polymers. Alternatively, the structure 56 may be made of an inert, bioabsorbable material that degrades during absorption or clearance by the body.

In another embodiment, the filler material 62 itself may be used as an expansion medium for the structure 56 to compact cancellous bone and form the cavity 60 to provide compression and internal support. Alternatively, the structure 56 is first expanded with another medium to compact cancellous bone and form the cavity 60, after removal of the expansion medium from the structure 56 and subsequent injection of the filler material 62, to provide internal support. Alternatively, the filler material may comprise a two-part material, including, but not limited to, a curable polymer or calcium alginate. If desired, a portion of the filler material may be used as an expansion medium and a second portion of the material added after the desired volume of the cavity is formed.

The structure 56 may be made of a permeable, semi-permeable, or porous material such that the drug contained in the filler material 62 may be delivered through the wall of the structure 56 and into contact with the cancellous bone. If desired, the material may comprise a film that is permeable to the material for permeation and/or particle transport, or the material may comprise a material that is permeable to the material for inhalation and/or diffusion of the drug. Alternatively, the drug may be delivered through the porous wall material by establishing a pressure differential across the walls of the structure 56.

As another alternative, fluid, cells, and/or other materials taken from the patient's body may be flowed into and/or drawn into the structure through the material for various purposes, including, but not limited to, fluid/cytoplasmic analysis, hyperostosis, bone marrow harvesting, and/or gene therapy (including gene replacement therapy).

Tool for forming a bone entry

During a typical bi-directional treatment, the patient lies on an operating table. Depending on the preference of the physician, the patient may lie down facing the table, or on his side, or at an oblique angle.

A. Using hand-held tools

For each access, (see fig. 10A), the physician inserts the spinal needle assembly 70 into the soft tissue ST of the patient's back. Under radiology or CT monitoring, the physician inserts the spinal needle assembly 70 down through soft tissue and into the targeted vertebral body 26. During surgery, the physician may also use the orienting tool to guide the advancement of the spinal needle assembly 70 and subsequent tools. In this configuration, a fiducial probe for directional guidance may be inserted through soft tissue and implanted into the surface of the targeted vertebral body. Tools and tags made of non-ferrous materials such as: plastics or fibre composites such as those disclosed in US5782764 and US5744958, the contents of which are incorporated herein by reference, are also suitable for use in a computer modified, whole room MRI environment.

The physician typically adds a local anesthetic, such as lidocaine, to the assembly 70. In some cases, the physician may prefer other modes of anesthesia.

The physician manipulates the spinal needle assembly 70 through the side of the vertebral body 26 to penetrate cortical bone 28 and cancellous bone 32. The depth of insertion is preferably 60% to 95% of the vertebral body 26.

The physician holds the stylus 72 and withdraws the probe 74 of the spinal needle assembly 70. As shown in FIG. 10B, the physician then slides the guide needle assembly 76 through the stylus 72 and inserts it into the cancellous bone 32. The physician can now remove the stylus 72, leaving the used guide needle assembly 76 in the cancellous bone 32.

As shown in FIG. 10C, the physician next slides the obturator instrument 78 over the distal end of the guide needle assembly 76. The physician can attach the occluding structure 78 to a handle 80 to facilitate manipulation of the occluding structure 78.

The physician makes a small incision in the back of the patient. The surgeon rotates the handle 80 while applying a longitudinal force on the handle 80. The obturator instrument 78 is then rotated and inserted through the incision and into the soft tissue. The physician may also gently tap the handle 80 or apply a suitable additional longitudinal force to the handle 80 to advance the obturator instrument 78 through the soft tissue along the guide pin assembly 76 down to the cortical bone entrance. The physician may also tap the handle 80 with a suitable striking tool to push the obturator instrument 78 into a side of the vertebral body 26 to secure it in place.

The outer diameter of the obturator instrument 78 shown in fig. 10C is generally well suited for establishing a side access. However, if access is desired through a narrower portion of the vertebral body 26, such as the root 42 (referred to as a transpedicular access), the outer diameter of the obturator instrument 78 is reduced. Reducing the outer diameter of the obturator instrument 78 accommodates damage or breakage of the root 42. It will be appreciated that the disclosed method and apparatus are particularly suitable for connecting other access channels by varying the results, for example: external, posterolateral and anterior access to the root, pedicle.

The physician can then continue to slide the handle 80 off of the obturator instrument 78 and slide the cannula instrument 84 over the guide needle assembly 76, and further, over the obturator instrument 78. If desired, the physician can also couple the handle 80 to the cannula instrument 84, perform the appropriate rotation, and apply a longitudinal force to rotate and advance the cannula instrument 84 over the obturator instrument 78 through the soft tissue. When the cannula instrument 84 is in contact with cortical bone 28, the physician then uses a striking tool to appropriately tap the handle 80 to push the end surface into the side of the vertebral body 26, securing it in place.

The physician can now withdraw the obturator instrument 78, slide it off the guide needle assembly 76, leaving the guide needle assembly 76 and cannula instrument 84 in place. If a reduced outer diameter obturator instrument 78 is used, the physician may also withdraw an internal centering sleeve (not shown).

As shown in fig. 10D, the physician first slides the drill bit structure 88 over the distal end of the guide pin assembly 76 through the cannula instrument 84 until the machined or cut outer edge 90 of the drill bit structure 88 and cortical bone 28 come into contact. The physician then attaches the drill bit structure 88 to the handle 80.

Under the guidance of X-rays (or another external visualization system), the physician applies rotational and longitudinal forces on the handle 80, rotating and advancing the machined outer edge 90 of the needle structure 88, opening a lateral passage PLA through the cortical bone 28 and into the cancellous bone 32. The drilled passage PLA preferably does not extend over 95% of the vertebral body 26.

Further details regarding the formation of cavities in cancellous bone (Asymmetric with respect to the axis of the vertebral Body) can be found in U.S. patent No. 5972018, entitled "Expandable Asymmetric Structure for use in a site in the Body" document, the contents of which are incorporated herein by reference.

Once the passage PLA is formed in the cancellous bone 32, as shown in FIG. 10E, the physician removes the drill bit structure 88 and the guide needle assembly 76, leaving only the cannula structure 84 in place. Retaining the passage PLA drilled by the bit structure 88. This creates a subcutaneous lateral access to the cancellous bone 32.

If desired, other tools may be used to make a subcutaneous access to the target bone, such as those described in pending U.S. patent application Ser. No. US09/421635, filed 1999, 10/19, entitled Manual tool for accessing a site in the body, the contents of which are incorporated herein by reference.

B. Filling the cavity

Once the cavity 64 is formed, the physician pre-prepares an injection of the filling material by filling the syringe 112 with the desired volume of filling material. If the expandable structure 56 is used in a preformed shape, the resulting cavity volume is known. The physician thus knows the desired volume of material 62, and places the desired volume of material 62 into the syringe 112 for each cavity formed in the vertebral body 26.

The physician attaches the nozzle 114 to the filled syringe 112. Thereafter, the physician continues to deflate and remove the expandable structure through the associated cannula instrument 84 and fill the associated cavity with material 62.

To fill the cavity, the physician inserts the nozzle 114 a distance into the cavity through an associated cannula instrument, guided, for example, by external markers 116 or by real-time fluoroscopy or X-ray or MRI visualization. The physician operates the syringe 112 to cause the material 62 to flow out through the nozzle 114 and into the cavity portion. As shown in fig. 10H, the inner diameter of nozzle 114 may be uniform, with the size of the distal end sized to facilitate insertion into the vertebral body. However, to reduce the overall flow resistance, the inner diameter of nozzle 114 (as shown in FIG. 11A) may be a step from a larger diameter at its proximal portion 118 to a smaller diameter near its distal end 120. This reduces the average inner diameter of the nozzle 114, thereby reducing the overall flow resistance. The reduced flow resistance allows more viscous materials to be delivered to the vertebral body. A more viscous material may be less likely to ooze out of the bone than a less viscous material, and thus may be more suitable.

In addition to the embodiment shown in FIG. 11A, various other configurations are possible to construct a reduced diameter nozzle or tool for introducing material into bone. For example, as shown in FIG. 11B, the inner conduit 162 of the tool 160 is gradually tapered from a larger inner diameter to a smaller inner diameter. Alternatively, as shown in FIG. 11C, the inner conduit 166 of the tool 164 is stepped from a larger inner diameter to a smaller inner diameter. The associated cannula instrument 168 (see FIG. 11C) may also include a reduced diameter passage that is smaller in size, accommodates a reduced diameter tool, and has less flow resistance to fill material delivered through the cannula instrument.

The reduced diameter tool can also be used in connection with vertebroplasty procedures, i.e., the injection of cement under pressure into a vertebral body, without having to pre-form a cavity.

The filler material 62 may comprise a predetermined amount of radiopaque material, such as barium or tungsten, sufficient to visualize the flow of material 62 into the cavity portion. The content of the radiopaque material is preferably at least 10%, more preferably at least 20%, and most preferably at least 30% by weight. The physician can thus observe the filling process of the cavity.

As the material 62 fills the cavity portion, the physician withdraws the nozzle 114 from the cavity portion and into the cannula instrument 84. The sleeve structure 84 directs material within the conduit toward the cavity portion. The material flows continuously into the cavity portion.

As shown in FIG. 10H, a gasket 122 may be provided around the cannula instrument 84 to seal the access passage PLA. The gasket 122 serves to prevent leakage of material from around the sleeve structure 84.

The physician operates the syringe 112 to drive the material 62 through the nozzle 114 first into the cavity portion and then into the cannula instrument 84. Generally, at the end of the syringe injection process, the material 62 will extend out of the cavity and occupy approximately 40% to 50% of the space of the sleeve structure 84. Alternatively, the physician may fill the catheter and/or cannula instrument 84 of the nozzle 114 with the material 62 from the syringe 112, and then drive the material from the catheter into the vertebral body using the tamping instrument 124.

When the desired volume of material 62 is driven from the syringe 112, the physician withdraws the nozzle 114 from the cannula instrument 84. The physician may first rotate the syringe 112 and nozzle 114 to break the mass of ejected material 62 occupying the space of the cannula instrument 84 loose the material 62 in the nozzle 144.

As shown in FIG. 10I, the physician next advances the tamping instrument 124 through the cannula instrument 84. The distal end of the tamping instrument 124 contacts the remaining volume of material 62 in the cannula instrument 84. Advancing the tamping instrument 124 progressively expels more of the remaining material 62 from the cannula instrument 84, forcing it into the cavity portion. The urging of the material 62 into the cavity portion by the urging of the tamping instrument 124 in the cannula instrument 84 serves to evenly distribute and compact the material 62 within the cavity portion, into other cavities and/or openings within the bone, and into the fracture line of the fracture without the use of too high a pressure.

The use of the syringe 112, nozzle 114 and tamping instrument 124 allows the physician to have precise control over the filling of the cavity portion with the material 62. The physician can immediately adjust the volume and volume delivered according to the particular local physiological conditions encountered. The application of uniform low pressure applied by the syringe 112 and the tamping instrument 124 allows the physician to react to the fill volume and flow resistance conditions in a virtually instantaneous manner. The chance of overfill and leakage of material 62 outside the cavity portion is greatly reduced.

Moreover, the tamping instrument 124 also provides good control over the amount of material 62 injected at higher injection pressures. For example, FIG. 12 shows a material injection configuration 500 including a reduced diameter nozzle 180 and a stylet 182. The probe 182 is sized to pass through the reduced diameter nozzle 180. Next, the nozzle 180 is sized to pass through the sleeve structure 184. As for the strength of the material, the nozzle 180 may be made of a substantially rigid metal material (e.g., stainless steel) or a high-strength plastic.

The stylet 182 includes a handle 192 that sits on the connector 186 at the proximal end of the nozzle when the stylet 182 is fully inserted into the nozzle 180. When the handle is set, the distal end of the stylet 182 is aligned with the nozzle 180. The probe 182 is positioned within the nozzle 180 to properly seal the internal bore.

In use, the nozzle 180 may be connected to the injector 104 and inserted through the cannula instrument 184 into a material receiving cavity (not shown) formed within a bone. The material 62 in the syringe 104 is injected into a nozzle 180 that is well suited for penetrating bone. When a sufficient amount of material 62 is injected into the bone and/or the nozzle 180, the syringe 104 can be withdrawn from the nozzle 180.

The stylet 182 is then inserted into the nozzle 180 and advanced through the nozzle, properly extruding the material 62 and pushing it out of the nozzle 180. In one disclosed embodiment, the diameter of the stylet 182 is approximately 0.118 inches. The cross-sectional area of the stylet 182 is approximately 0.010936 square inches, and the nozzle 180 desirably contains approximately 1.5 milliliters of filler material. In an alternative embodiment, the diameter of the stylet 182 is approximately 0.136 inches.

The filling material 62 may be pushed into the bone through the cannula instrument 184 using a nozzle 180 and stylet 182 similar to the combination plunger instrument 183. For example, when the filler material 62 is located in the cannula instrument 184, insertion of the plunger mechanism 183 into the cannula 184 will desirably displace the material 62, forcing the material 62 from the distal end of the cannula 184 into the bone. In one embodiment, the diameter of the ram structure 183 is about 0.143 inches. As the plunger structure 183 is advanced through the cannula 184, it desirably displaces the filler material 62 within the cannula 184. Thus, the plunger structure 183 acts as a positive displacement "piston" or "pump" that allows the physician to accurately measure the precise amount of filler material 62 that is injected into the bone.

If the fill material is very viscous, such material typically has a significant resistance when pumped through the delivery system. Generally, the longer the distance the filling material must travel through the system, the greater the pressure loss due to such factors as the viscosity of the material and the frictional losses with the inner wall. To account for these losses, existing delivery systems typically force the filler material very forcefully, typically up to several thousand pounds of pressure. This not only requires a more powerful pump and a robust connection for the delivery system, but the system is often unable to dispense very precise amounts of filler material. Moreover, if the filler material hardens over a long period of time, the system must generate even greater pressure to overcome the increase in material flow resistance.

The disclosed systems and methods avoid and/or reduce the complexity and high pressure requirements of injection systems for delivering filler materials. Because the disclosed plunger structure 183 travels subcutaneously through the cannula 184 and pushes the filler material 62 out the distal end of the cannula 184, the amount of filler material pushed by the plunger structure 183 (and the total amount of filler material 62 in the cannula 184) is continuously reduced as filler material is injected into the bone. This desirably reduces the resulting resistance to movement of the plunger structure during injection. Furthermore, since the amount of material pushed by the plunger structure 183 is reduced, the increase in flow resistance when curing the filler material does not require an increase in injection pressure. In addition, because the plunger structure 183 travels inside the cannula 184 and is able to pass percutaneously through the injection site, the need for very high pressures can be further reduced by pumping only a short length of filler material before it exits the cannula and enters the bone. If injection of the secondary filling material is desired, the plunger structure may be withdrawn from the cannula, the secondary filling material introduced into the cannula, and the process repeated. Thus, the device allows even very viscous materials to be injected smoothly with good control. Also, by varying the diameter of the cannula, nozzle and probe, a wide range of pressures can be generated in the filler material 62. If desired, the disclosed device can similarly be used to inject a filling material directly into a bone through a spinal needle assembly or to fill a cavity formed in a bone during vertebroplasty.

If desired, the physician may also choose to continue injecting the auxiliary material 62 into the vertebral body after filling the cavity with the material 62. Depending on the local conditions within the bone, such additional material may be used to simply increase the volume of the cavity (by further compressing the cancellous bone) or may be injected into the compressed and/or uncompressed cancellous bone surrounding the cavity, which may serve to further compress the cancellous bone and/or further increase the compressive strength of the vertebral body.

When the physician is satisfied that the material 62 is sufficiently distributed within the interior of the cavity portion, the tamping instrument 124 can be withdrawn from the cannula instrument 84. The physician preferably first twists the tamping instrument 124 to cleanly break contact with the material 62.

Once the cavity is filled and plugged using the methods described above, the cannula instrument 84 is withdrawn and the incision site is sutured closed.

If the material 62 is an adhesive, it will eventually harden to a hard state inside the cavity 64. Thereby increasing the capacity of the vertebral body to bear loads.

Fig. 9B through 9D illustrate an alternative method of filling a cavity 60 formed in a vertebral body. In this embodiment, the cannula instrument 84 has been inserted through the pedicle 42 of the vertebral body by providing access to the cavity 60 formed therein. The nozzle 180 is advanced into the vertebral body with the distal end of the nozzle 180 appropriately positioned adjacent the anterior side of the cavity 60. The filler material 62 is slowly injected into the cavity 60 through the nozzle 180. As shown in fig. 9C, the nozzle 180 may be drawn toward the center of the cavity 60 while the filling material 62 is continuously injected. Preferably, the nozzle 180 is withdrawn such that the distal end of the nozzle 180 remains substantially in contact with the growing mass of filler material 60. Once the nozzle 180 is positioned near the center of the cavity 60, the secondary fill material 62 is injected through the nozzle 180 to substantially fill the cavity 60. Thereafter, the nozzle is pulled out of the cavity 60.

If desired, the nozzle may be connected to a syringe 104 (see FIG. 12) containing the filler material. In one embodiment, the syringe 104 contains an amount of filler material equal to the volume of the cavity 60 formed in the vertebral body, with the nozzle containing an additional 1.5 milliliters of filler material. In this embodiment, the cavity 60 is initially filled with the filler material expelled from the syringe 104. Once exhausted, the syringe 104 is withdrawn from the nozzle 180, the stylet 182 is inserted into the nozzle 180, and the remaining filler material inside the nozzle 180 is pushed into the vertebral body using the stylet 182. Preferably, the supplemental filler material from the nozzle 180 is forced outwardly into the cancellous bone to compact additional cancellous bone and/or to slightly increase the size of the cavity 60.

The disclosed method advantageously ensures complete filling of the cavity with the filler material. Since patients often lie anteriorly down during the disclosed procedure, the anterior portion of the cavity is typically the lowest portion of the cavity. The front of the cavity is first filled with the filler material and then the rear of the cavity is filled, and the fluid and/or suspended solids inside the cavity are suitably displaced by the filler material and move to the rear of the cavity, from where they exit the cannula. In this way, pooling of fluid and/or filler material inside the cavity is avoided and complete proper filling of the vertebral body can be ensured.

If desired, the filler material may be hardened and/or cured prior to injection into the vertebral body. For example, in one embodiment, the filler material comprises a bone cement that can be cured to a glue or putty-like state prior to injection into the cavity. In this embodiment, the adhesive preferably has a consistency similar to toothpaste when it begins to exit the nozzle.

The Material 62 selected may also be autograft or allograft Bone Graft tissue collected in conventional manner, such as in the form of an ointment (see "Use of the experimental reader to Harvest automatic Bone Graft Material: A simple method for Producing Bone Paste",Archives of Orthopaedic and Traumatic Surgery(1986),105: 235-238), or in pill form (see "persistent Bone Grafting for non and Delayed Union of the fuels of the biological Shift" of Bhan et al,International orthopaedics(SICOT)(1993) 17：310-312). Alternatively, bone graft collection may be employedBone Graft tissue was obtained from a Bone Graft Harvester (Bone Graft Harvester), a device commercially available from Spinetech. The cannula structure 84 is filled with a graft tissue material in the form of a paste or pellet using a funnel. Thereafter, the tamping instrument 124 is advanced into the cannula instrument 84 in the manner described above, and the graft tissue material, in the form of a paste or pellet, is advanced out of the cannula instrument 84 and into the cavity portion.

The selected material 62 may comprise a particulate bone material harvested from coral, such as the Proosteopon calcium carbonate particles available from Interpore. The particles are loaded into the sleeve structure 84 by a funnel and pushed into the cavity by the tamping structure 124.

The selected material 62 may also include demineralized bone matrix suspended in glycerol (e.g., Grafton allograft material available from ostoetech), or SRS available from Norian^*A calcium phosphate binder. These viscous materials, such as the bone cement described above, are injected into the syringe 112 and into the cavity using the nozzle 114 inserted through the cannula instrument 84 into the cavity portion. As described above, the tamping instrument 124 is used to push the remaining material from the cannula instrument 84 into the cavity portion.

The selected material 62 may also be in the form of a sheet, such as a Collagraft made of calcium carbonate powder^*Material and collagen made from bovine bone. The sheet may be rolled into a tube and manually inserted into the sleeve structure 84. Thereafter, the tamping instrument 124 is advanced through the cannula instrument 84 to push and compress the material within the cavity portion.

C. Multi-stage injection instrument

Figures 13A and 13B illustrate one embodiment of a filling structure for introducing a desired amount of filler material into a bone or other vertebral body. The filling structure 600 comprises a first portion 605 and a second portion 610. The first and second sections 605 and 610 are preferably hollow tubes that are connected and/or secured in a sealed relationship, with the interior of the first section 605 being in fluid communication with the interior of the second section 610.

The first portion 605 has a first internal cross-sectional area 615 and the second portion 610 has a second internal cross-sectional area 620. Preferably, the first internal cross-sectional area 615 is greater than the second internal cross-sectional area 620. In the disclosed embodiment, the first portion 605 comprises a cylindrical, hollow tubular member having an inner diameter of 0.358 inches and a length of 2.58 inches, while the second portion 610 comprises a cylindrical, hollow tubular member having an inner diameter of 0.175 inches and a length of 8.84 inches.

The dispensing aperture 640 is disposed at the distal end 645 of the second portion 610. A first plunger opening 650 is provided at the proximal end of the first portion 605. If desired, a flange 655 may be provided on the exterior of the first section 605. If desired, as shown in FIG. 13A, the transition from the first section 605 to the second section 610 is a bottleneck or taper.

Fig. 14A and 14B illustrate a first plunger assembly 700 suitable for use with the filling structure 600 described herein. The first plunger assembly 700 includes a first plunger 705 sized to pass through the interior of the first portion 605. A seal 710, such as an O-ring, is secured to the distal end 715 of the first plunger 705 in a manner well known in the art. Preferably, the seal 710 slidingly engages the inner wall of the first section 605 as the first plunger 705 slides therein, thereby sealing the proximal end of the first section 605. Preferably, the gasket 710 comprises Teflon (Teflon), natural rubber, or other type of sealant material. It should be noted that although the cross-section of the disclosed plunger is circular (see fig. 14B), the cross-section of the plunger used may vary from case to case and may be of other similar shapes, such as triangular or rectangular.

If desired, a plunger flange 725 may be provided at the distal end of the first plunger 705. Preferably, the plunger flange 725 abuts and/or contacts the flange 655 when the distal end of the first plunger 700 reaches a desired position near or adjacent to the distal end of the first section 605. The first plunger assembly 700 further includes a second plunger opening 720 extending longitudinally through the first plunger 705. Preferably, the second plunger opening 720 has a cross-sectional area that is sized and shaped to be smaller than or close to the size and shape of the second interior cross-sectional area 620. In the disclosed embodiment, the first plunger assembly 700 is 2.62 inches long, the first plunger 705 has an outer diameter of 0.357 inches, and the second plunger bore 720 has an inner diameter of 0.115 inches.

Fig. 15 illustrates a second plunger assembly 750 suitable for use with the first plunger assembly 700 and the filling structure 600. The second plunger assembly 750 includes a second plunger 755 and a knob 760 secured to the proximal end of the second plunger 755. The second plunger 755 is preferably sized to pass through the second plunger opening 755 and the second portion 610. In one embodiment, the second plunger assembly further comprises a groove 765. A retaining clamp 800 (see fig. 16A-16C) is preferably provided to releasably secure the second plunger assembly 750 within the second plunger opening 755. In the disclosed embodiment, the second plunger assembly 750 is 11.8 inches long, the outer diameter of the second plunger 755 is 0.113 inches, and the groove 765 is disposed about 2.62 inches from the distal end of the second plunger 755.

With respect to the strength of the material, the various components of the filling structure 600 may comprise a substantially rigid metal, plastic, or ceramic material, such as stainless steel or a high strength plastic. In the disclosed embodiment, the packing structure 600 and the second plunger assembly comprise 303 stainless steel, while the first plunger assembly comprises Delrin @^*Plastic (commercially available from Dupont).

When it is desired to inject a filler material, the filler instrument 600 is filled with a filler material (not shown), such as bone cement or PMMA. The second plunger assembly 750 is secured inside the first plunger assembly using a locating clip 800. The distal end 715 of the first plunger 705 is then inserted into the first plunger opening 650.

As the first plunger 705 is advanced through the first section 605 of the filling structure 600, the plunger 705 pushes the filling material in the first section 605 and subsequently forces the material in the second section 610 out through the dispensing opening 640. The provision of the second plunger 755 prevents substantial amounts of filler material from passing through the second plunger opening 755, preferably by holding the second plunger in place with the retaining clamp 800. When the distal end 715 reaches the distal end of the first section 605, preferably substantially all of the filler material is discharged from the first section 605 into the second section 610 and/or out of the dispensing opening 640.

Thereafter, the retaining clip 800 is released and the second plunger 755 is advanced through the distal end of the first section 605 and into the second section 610. Preferably, the cross-sectional shape and size of the second plunger 755 is similar to the shape and size of the cross-section 620 of the second section 610, such that the second plunger 755 can displace substantially all of the filler material in the second section 610 as the second plunger 755 is pushed. Preferably, once the distal end of the second plunger 755 reaches the dispensing opening 640, substantially all of the filler material within the first and second sections 605 and 610 is dispensed from the filling structure 600.

The present invention advantageously dispenses a substantial amount of filler material from a single filling structure by utilizing first and second portions of different cross-sectional areas and first and second plungers to displace the filler material. Since the viscosity of PMMA and various other types of filler materials generally increases over time during dispensing, it becomes increasingly difficult to deliver the filler material over time. The present invention enables a large amount of filler material to be delivered if the filler material has a low viscosity when the filling operation is initiated with a plunger of larger cross-sectional area. However, as the filler material solidifies, it becomes more viscous, and therefore, even in the case of being very viscous, reducing the cross-sectional area of the second plunger enables the continuous delivery of the more viscous filler material. However, because of the reduced cross-sectional area of the second portion, the reduced profile thereof may be advanced well through the cannula and/or soft tissue into the distal end of the filling structure to provide direct access to the targeted vertebral body, while still providing sufficient volume of filling material to accomplish the purpose of growing and/or repairing the targeted bone. Moreover, since during the dispensing operation, although the tool need not be refilled and/or cut off, it is still preferred to leave it in place and dispense all of the required amount of bone filler material during the process, thereby greatly reducing the likelihood of air entrapment within the vertebral body and/or the cement mass.

The present invention also greatly facilitates the ability of the physician to switch from a relatively large volume, low pressure adhesive flow condition to a relatively small volume, high pressure adhesive flow condition. By injecting cement into the vertebral body while pushing on the first plunger, the physician may determine that more controlled, higher pressure, and/or lower volume flowable cement is needed. Alternatively, the adhesive may cure or harden to the point where it is very difficult and/or impossible to move the first plunger further. An embodiment of the present invention allows a physician to push the second plunger into the second section even when the distal end of the first plunger is not near and/or adjacent to the distal end of the first section. Once the second plunger has passed through the adhesive in the first section and into the second section, the adhesive can be expelled from the second section. Because the cross-sectional area of the second plunger and the second section is reduced (compared to the first plunger and the first section), it is easier to push the second plunger through the adhesive in the first section and to deliver the adhesive from section 2 at a higher pressure and/or lower volume.

The disclosed filling structure may be used to introduce a filling material through a cannula into a cavity formed within a bone, or may be used in conjunction with vertebroplasty, which introduces the filling material directly into the vertebral body without having to form a cavity in advance. If a previously formed cavity is not required and/or desired, and vertebroplasty is used, the filling structure can be provided with a needle point at its distal end, or the diameter of the second portion can be greatly reduced, allowing passage of the structure through the catheter of the spinal needle assembly. Alternatively, one or more portions of the filling structure include a commercially available spinal Needle assembly (e.g., Bone Marrow Biopsy Needle No. 508627, available from Becton Dickinson & co., Franklin Lakes, NJ, 07417). If desired, one or more plunger assemblies of varying size and length may be provided to accommodate different spinal needle assemblies.

If desired, the filling structure can be pre-loaded with a filler material, penetrated through soft tissue and inserted into the vertebral body for injection of the filler material, and quickly and easily extracted without the need to change tools during the procedure. For example, when the end plate of the vertebral body is pressed to a position where the expandable structure cannot be safely inserted and/or expanded within the vertebral body, bone cement is injected under pressure through the needle directly into the cancellous bone (without forming a cavity) in the vertebral body. The bone cement penetrates into the cancellous bone.

To reduce the flow resistance to the filler material, the filler structure is provided with an increased internal diameter, as shown in fig. 11A, 11B, or 11C. The reduced flow resistance may allow the use of a more viscous cement, further reducing the likelihood of cement extrusion from the vertebral body.

Figures 17A through 17D and figure 18 illustrate an alternative embodiment of a fill structure provided in accordance with the teachings of the present invention. Since many features of this embodiment are similar to those of the embodiments described above, like reference numerals are used to denote like parts. In this embodiment, the first plunger assembly 700A further includes an increased cross-sectional end opening 850 located within the distal end 715A of the assembly 700A. The end opening 850 corresponds to an increased cross-sectional plunger end 855 on the second plunger 755.

During use of the filling structure 600A, the plunger tip 855 is positioned within the tip opening 850 while the first plunger 705A is advanced, desirably preventing the second plunger 750A from moving axially as the pressure of the filling material increases. If desired, a clamp (not shown) may be used to secure the second plunger to the first plunger. Once the first plunger 705A is pushed into its desired position, the clamp (not shown) may be removed from the recess 765A and the second plunger 750A pushed as described above.

Figures 19A through 19D illustrate a fill structure 600B according to another alternative embodiment provided in accordance with the teachings of the present invention. Since many features of this embodiment are similar to those of the embodiments described above, like reference numerals are used to denote like parts. In this embodiment, the first plunger assembly 700B includes a one-way valve 900 at the distal end 715 of the assembly 700B. The one-way valve 900 desirably prevents filler material from passing through the second plunger opening 755B when the first plunger 705B is pushed. Once the first plunger assembly 700B is pushed into its desired position and the second plunger assembly is pushed through the second plunger opening, the check valve 900 allows the second plunger to pass through the first and second sections as described above.

The invention is characterized by what is presented in the following claims.

Claims (6)

1. A system for introducing material into bone, comprising:

a filling structure comprising a first cavity portion and a second cavity portion, the first cavity portion having a first cross-sectional area and the second cavity portion having a second cross-sectional area smaller than the first cross-sectional area, the second cavity portion communicating with the first cavity portion, the first cavity portion comprising an inlet for receiving material flowing into the filling structure and the second cavity portion comprising an outlet for discharging material from the filling structure;

a first plunger sized to pass through the first cavity portion but not the second cavity portion, the first plunger including an internal bore such that the first plunger expels material residing in the first cavity portion through the second cavity portion toward the outlet; and

a second plunger sized to pass through the inner bore of the first plunger and be inserted into the second cavity portion such that the second plunger expels material residing in the second cavity portion through the outlet.

2. The system of claim 1, wherein the first internal cross-sectional area remains substantially constant along a longitudinal axis of the first cavity portion.

3. The system of claim 1, wherein the second internal cross-sectional area remains substantially constant along a longitudinal axis of the second cavity portion.

4. The system of claim 1, wherein the first internal cross-sectional area varies across the first cavity portion.

5. The system of claim 1, wherein the second internal cross-sectional area varies across the second cavity portion.

6. The system of claim 1, wherein the first plunger further comprises a seal disposed near a distal end of the first plunger.