Multi-port delivery system

This application is a continuation of application Ser. No. 12/771,812, filed on Apr. 30, 2010, the contents of which are herein incorporated by reference in their entirety.

The invention relates to a system and method for performing a surgical procedure, and in particular, to a pressure delivery device that provides multiple output ports in a single instrument.

A minimally invasive procedure is a medical procedure that is performed through the skin or an anatomical opening. In contrast to an open procedure for the same purpose, a minimally invasive procedure will generally be less traumatic to the patient and result in a reduced recovery period.

However, there are numerous challenges that minimally invasive procedures present. For example, minimally invasive procedures are typically more time-consuming than their open procedure analogues due to the challenges of working within a constrained operative pathway. In addition, without direct visual feedback into the operative location, accurately selecting, sizing, placing, and/or applying minimally invasive surgical instruments and/or treatment materials/devices can be difficult.

For example, for many individuals in our aging world population, undiagnosed and/or untreatable bone strength losses have weakened these individuals' bones to a point that even normal daily activities pose a significant threat of fracture. In one common scenario, when the bones of the spine are sufficiently weakened, the compressive forces in the spine can cause fracture and/or deformation of the vertebral bodies. For sufficiently weakened bone, even normal daily activities like walking down steps or carrying groceries can cause a collapse of one or more spinal bones. A fracture of the vertebral body in this manner is typically referred to as a vertebral compression fracture. Other commonly occurring fractures resulting from weakened bones can include hip, wrist, knee and ankle fractures, to name a few.

Fractures such as vertebral compression fractures often result in episodes of pain that are chronic and intense. Aside from the pain caused by the fracture itself, the involvement of the spinal column can result in pinched and/or damaged nerves, causing paralysis, loss of function, and intense pain which radiates throughout the patient's body. Even where nerves are not affected, however, the intense pain associated with all types of fractures is debilitating, resulting in a great deal of stress, impaired mobility and other long-term consequences. For example, progressive spinal fractures can, over time, cause serious deformation of the spine (“kyphosis”), giving an individual a hunched-back appearance, and can also result in significantly reduced lung capacity and increased mortality.

Because patients with these problems are typically older, and often suffer from various other significant health complications, many of these individuals are unable to tolerate invasive surgery. Therefore, in an effort to more effectively and directly treat vertebral compression fractures, minimally invasive techniques such as vertebroplasty and, subsequently, kyphoplasty, have been developed. Vertebroplasty involves the injection of a flowable reinforcing material, usually polymethylmethacrylate (PMMA—commonly known as bone cement), into a fractured, weakened, or diseased vertebral body. Shortly after injection, the liquid filling material hardens or polymerizes, desirably supporting the vertebral body internally, alleviating pain and preventing further collapse of the injected vertebral body.

Because the liquid bone cement naturally follows the path of least resistance within bone, and because the small-diameter needles used to deliver bone cement in vertebroplasty procedure require either high delivery pressures and/or less viscous bone cements, ensuring that the bone cement remains within the already compromised vertebral body is a significant concern in vertebroplasty procedures. Kyphoplasty addresses this issue by first creating a cavity within the vertebral body (e.g., with an inflatable balloon) and then filling that cavity with bone filler material. The cavity provides a natural containment region that minimizes the risk of bone filler material escape from the vertebral body. An additional benefit of kyphoplasty is that the creation of the cavity can also restore the original height of the vertebral body, further enhancing the benefit of the procedure.

Typically, kyphoplasty is performed using a bilateral procedure, in which access to the interior of the vertebral body is achieved via pedicular access. Cavities are created in both the left and right halves of the vertebral body interior, and subsequently filled with bone filler material. This bilateral approach can often create a more stable support structure than would be possible using only a unipedicular approach, and can also enhance vertebral body height restoration and maintenance.

However, because conventional cement delivery systems provide only a single delivery output, filling the two cavities can be a cumbersome task. A separate cement delivery system could be used for each cavity, or a single cement delivery system must be moved between the two access cannulas. In either case, the logistics of performing the cement delivery are less than ideal, as the physician performing the procedure is forced to either interact with two separate delivery devices or physically transport a single delivery device between cannulas.

Accordingly, it is desirable to provide surgical tools and techniques that enable user-friendly material delivery during surgical procedures.

By incorporating a diverter element into a pump with multiple outputs, a material delivery system can service multiple surgical target locations from a single control point.

In various embodiments, a material delivery system can include a pressure reservoir, a pressure source for pressurizing the pressure reservoir, and a diverter for selectably coupling the pressure reservoir to one of multiple outputs. In some embodiments, the pressure reservoir can include a pressure release valve for venting the pressure reservoir to a predetermined baseline pressure (e.g., ambient/atmospheric pressure). The diverter can be configured to trigger (open) the pressure release valve whenever switching between different outputs. Alternatively, the diverter can itself vent the pressure reservoir during switching (e.g., by creating a flow path from the pressure reservoir to the baseline pressure). By automatically venting during the switching process, unintended and/or uncontrolled material delivery can be prevented when the pressure reservoir is initially coupled to the new output. In various embodiments, this vent triggering can occur while one or both of the original and destination outputs are coupled to the pressure reservoir.

In various embodiments, the pressure reservoir can contain a hydraulic fluid that transmits the pressure within the pressure reservoir to a remote material dispensing element (e.g., via hydraulic lines/flexible tubing). The material dispending element then dispenses the actual flowable material (e.g., bone filler material) in response to the pressure transmitted via the hydraulic fluid. In various other embodiments, the pressure reservoir can contain the actual flowable material that is expressed from the pressure reservoir through the selected output.

In various embodiments, a surgical procedure (e.g., kyphoplasty) can be performed using a single material delivery system that includes multiple outputs selectably coupled to a single pressure reservoir. The flowable material can be delivered to each the different surgical target locations individually by manually switching between the different outputs. In various embodiments, switching between different outputs automatically vents the pressure reservoir to a baseline pressure. As a result, sudden high pressure output from the new output can be prevented, thereby minimizing the risk of adverse events during the surgical procedure (e.g., cement extravasation during kyphoplasty or vertebroplasty).

As will be realized by those of skilled in the art, many different embodiments of a multi-output material delivery system, along with systems, kits, and/or methods of using such a material delivery system are possible. Additional uses, advantages, and features of such a material delivery system are set forth in the illustrative embodiments discussed in the detailed description herein and will become more apparent to those skilled in the art upon examination of the following.

FIGS. 1A-1D show an exemplary schematic diagram of a material delivery system having multiple selectable outputs.

FIGS. 2A-2F show an exemplary implementation of the multi-output material delivery system of FIGS. 1A-1D .

FIGS. 3A-3G show an exemplary bilateral kyphoplasty procedure performed using the multi-output material delivery system of FIGS. 2A-2F .

FIGS. 4A-4C show another exemplary implementation of the multi-output material delivery system of FIGS. 1A-1D .

FIGS. 5A-5D show another exemplary implementation of the multi-output material delivery system of FIGS. 1A-1D .

By incorporating a diverter element into a material delivery system with multiple outputs, the material delivery system can service multiple surgical targets from a single control point.

FIG. 1A is a schematic diagram of a material delivery system 100 that includes multiple material dispensing outlets 151 . For exemplary purposes, material delivery system 100 is depicted as having two dispensing outlets 151 A and 151 B, but in various other embodiments, material delivery system 100 can include any number of dispensing outlets 151 . Material delivery system 100 further includes a pressure reservoir 110 , a pressure source 120 , a diverter 130 , a pressure release valve 140 , pressure outlets 150 A and 1506 , and material dispensing elements 155 A and 155 B.

Pressure source 120 can be any system for pressurizing pressure reservoir 110 . In one embodiment, pressure source 120 can be a basic hand pump for driving a piston or plunger (e.g., via a squeeze trigger or crank) to pressurize reservoir 110 . In various other embodiments, pressure source 120 can be a powered hydraulic pump or precharged pressure vessel coupled to pressure reservoir 110 by a valve. Any number of additional alternatives will be readily apparent.

Diverter 130 selectably couples pressure reservoir 110 to one of pressure outlets 150 A and 150 B, and therefore to one of material dispensing elements 155 A and 155 B, respectively. This pressure application causes the recipient material dispensing system 155 to express a flowable material from its associated dispensing outlet 151 . Note that “flowable material” as described herein can be any material capable of being dispensed from material delivery system 100 , such as PMMA, granulized or pelletized material such as bone morphongenic protein (BMP) or graft material, or even solid materials that can be forced from material dispensing elements 155 A and 155 B (e.g., wax or phase-change materials). In various embodiments, pressure reservoir 110 can contain the flowable material itself, such that when diverter 130 couples pressure reservoir 110 to, for example, material dispensing element 155 A, the flowable material simply flows from pressure reservoir 110 through diverter 130 , through material dispensing element 155 A, and out of dispensing outlet 151 A.

However, in various other embodiments, pressure reservoir 110 can contain a hydraulic fluid (e.g., water, saline solution, or oil, among others) for driving the flowable material from material dispensing elements 155 A and 155 B. For example, as shown in FIG. 1A , material dispensing element 155 A could include a piston 153 A that receives hydraulic fluid pressure from pressure reservoir 110 , and in response to such pressure forces flowable material out of material dispensing element 155 A through dispensing outlet 151 A.

In various hydraulic fluid-based embodiments of material delivery system 100 , material dispensing elements 155 A and 155 B could be coupled to pressure outlets 150 A and 150 B, respectively, by hydraulic lines (e.g., flexible tubing). This would allow dispensing outlets 151 A and 151 B to be positioned more remotely than would be typically be feasible if the actual flowable material were being forced directly from pressure reservoir 110 .

In various other embodiments, material delivery system 100 can also include pressure release valve 140 . Pressure release valve 140 is a normally closed valve that, when actuated, vents pressure reservoir 110 to a lower pressure region. Typically, the lower pressure region will be at ambient pressure (e.g., atmospheric pressure), but in various embodiments, the venting can be to a predetermined baseline pressure other than atmospheric pressure. In some embodiments, pressure release valve 140 can vent outside of the pressure system (i.e., an open system) as indicated by the solid arrow, and in other embodiments, pressure release valve 140 can vent back into the pressure system (i.e., a closed system) as indicated by the dotted arrow returning to pressure source 120 .

When present, pressure release valve 140 can be triggered by the action of diverter 130 . Specifically, switching diverter 130 between outputs can open pressure release valve 140 , thereby ensuring that the newly coupled material dispensing element 155 does not receive a sudden high pressure surge. This automatic pressure “reset” prevents unexpected and/or uncontrolled material delivery from the newly selected material dispensing element 155 , which can be a critical safety factor during a medical procedure (as described in greater detail below).

For example, in FIG. 1A , diverter 130 is positioned to couple pressure reservoir 110 to material dispensing element 155 A. Therefore, as pressure source 120 pressurizes pressure reservoir 110 , flowable material is dispensed from dispensing outlet 151 A. As described above, this dispensing can be due either to either to hydraulic pressure delivered via a hydraulic fluid in pressure reservoir 110 (e.g., causing piston 153 A to force the flowable material from material dispensing element 155 A), or to the flowable material being driven from pressure reservoir 110 through diverter 130 and through material dispensing element 155 A.

Once a desired amount of flowable material has been expressed from dispensing outlet 151 A, diverter 130 can be switched to a new position to couple pressure reservoir 110 to material dispensing element 155 B. In one embodiment, as indicated in FIG. 1B , the initiation of this switching operation opens pressure release valve 140 , thereby venting pressure reservoir 110 . In addition, any residual pressure at material dispensing element 155 A can be eliminated by configuring diverter 130 and/or pressure release valve 140 such that pressure release valve 140 opens while diverter 130 is still coupling pressure reservoir 110 to material dispensing element 155 A. By doing so, material flow from dispensing outlet 151 A can be immediately stopped once switching begins.

In various embodiments, pressure release valve 140 remains open as diverter 130 couples pressure reservoir 110 to material dispensing element 155 B, as shown in FIG. 1C . In doing so, any pressure differential between pressure reservoir 110 and newly connected material dispensing element 155 B can be immediately eliminated without creating any unintentional discharge of flowable material from dispensing outlet 151 B.

Note that for exemplary purposes diverter 130 is depicted as creating discrete connections between pressure reservoir 110 and material dispensing element 155 A and between pressure reservoir 110 and material dispensing element 155 B. However, in various other embodiments, diverter 130 can exhibit a mode in which pressure reservoir 110 is simultaneously coupled to both material dispensing elements 155 A and 155 B. Opening pressure release valve 140 during such a mode would simultaneously equalize pressures at pressure reservoir 110 and material dispensing elements 155 A and 155 B.

When diverter 130 is fully switched to its new position, pressure release valve 140 is closed, as shown in FIG. 1D . Pressure source 120 can then be used to pressurize pressure reservoir 110 to dispense flowable material from material dispensing element 155 B, in a manner substantially similar to that described with respect to material dispensing element 155 A in FIG. 1A .

FIG. 2A shows an embodiment of material delivery system 100 (described with respect to FIGS. 1A-1D ) in which diverter 130 is a rotational element that defines a flow path 131 . In FIG. 2A , flow path 131 is positioned over an outlet 111 of pressure reservoir 110 and an input to pressure outlet 150 A. Accordingly, as shown in cross section A-A in FIG. 2B , flow path 131 connects pressure reservoir 110 to pressure outlet 150 A, thereby coupling pressure reservoir 110 to material dispensing element 155 A (depicted by a phantom outline for simplicity's sake) to dispense flowable material.

Note that while flow path 131 is depicted as a hollowed-out portion of diverter 130 for exemplary purposes, in various other embodiments, flow path 131 can take any configuration or shape. For example, in various embodiments, flow path 131 can be a passageway within diverter 130 . Note further that while diverter 130 is depicted and described as a rotational element for exemplary purposes, diverter 130 can exhibit any mode of operation that enables output switching capability. For example, in various embodiments, diverter 130 can be a push-pull element, a rotating ball or cylinder valve, or a movable lever, among others.

For exemplary purposes, pressure generator 120 is depicted as a simple piston 121 that pressurizes pressure reservoir 110 through a one-way check valve 122 . Such an embodiment is particularly conducive to pressure generation in a hand-held device. For example, pressure generator 120 can include a trigger 122 that, in response to pressure (e.g., squeezing) by the operator, drives piston 121 inward to pressurize pressure reservoir 110 .

Likewise, for exemplary purposes, pressure release valve 140 is depicted as a simple one-way check valve with an actuator 142 . Note that in various other embodiments, pressure release valve 140 can incorporate any pressure release mechanism. Raising actuator 142 vents pressure reservoir 110 to ambient pressure (although as described above with respect to FIGS. 1A-1D , in various other embodiments, pressure release valve 140 can be configured to vent to any baseline pressure, either as an open or closed system).

Diverter 130 also includes a triggering feature 132 that is configured to actuate (open) pressure release valve 140 as diverter 130 is rotated. For exemplary purposes, triggering feature 132 is depicted as a raised element on diverter 130 that can slip under actuator 142 . Note, however, that in various other embodiments, triggering feature 132 can be any system for actuating pressure release valve 140 , including a magnetic switch, a proximity sensor, and/or a mechanical linkage.

Thus, as diverter 130 is rotated, as shown in FIG. 2C , triggering feature 132 slides under actuator 142 , as shown in the cross sectional view of FIG. 2D . This action opens pressure release valve 140 , thereby venting pressure reservoir 110 to a baseline pressure P 0 (e.g., atmospheric pressure). Because flow path 131 still couples pressure reservoir 110 to pressure outlet 150 A, the pressure at material dispensing element 155 A is also reduced to baseline pressure P 0 . As indicated in FIG. 2C , flow path 131 is sized and shaped to also couple pressure reservoir 110 to pressure outlet 150 B during the actuation of pressure release valve 140 , thereby establishing baseline pressure PO at pressure outlet 150 B (and hence at material dispensing element 155 B, which is not shown for clarity).

Then, as switching is completed as shown in FIG. 2E , triggering feature 132 is moved out from under actuator 142 , thereby closing pressure release valve 140 , as shown in cross sectional view A-A in FIG. 2F . Meanwhile, flow path 131 decouples pressure outlet 150 A from pressure reservoir 110 (while maintaining the path between pressure reservoir 110 and pressure outlet 150 B). Accordingly, as pressure reservoir 110 is pressurized by pressure generator 120 (e.g., by depressing piston 121 ), the new pressure P 2 created within pressure reservoir 110 is transmitted to pressure outlet 150 B, while the pressure at pressure outlet 150 A remains at the baseline pressure P 0 .

Note that in various embodiments, diverter 130 can couple pressure reservoir 100 to both pressure outlets 150 A and 150 B (as shown in FIG. 2C ) without triggering pressure release valve 140 , (e.g., triggering feature 132 could be absent from diverter 130 ). In such embodiments, material delivery system 100 could dispense material individually or simultaneously from material dispensing elements 155 A and 155 B.

FIG. 4A shows another embodiment of material delivery system 100 (described with respect to FIGS. 1A-1D ) in which diverter 130 is a sliding element that defines a primary flow path 131 A and a secondary flow path 131 B. In particular, diverter 130 is positioned in a passage 139 within housing 101 , and includes sealing elements 136 (e.g., o-rings or gaskets) that close passage 139 at various locations. Outlets 150 A and 150 B, pressure reservoir outlet 111 , optional pressure release valve 140 , and optional bleed ports 141 A and 141 B all feed in to passage 139 , and are interconnected amongst each other by the particular locations of sealing elements 136 .

For example, in FIG. 4A , flow path 131 A connects pressure reservoir outlet 111 (the pressure reservoir itself is not shown for simplicity, but can be similar to pressure reservoir 110 described with respect to FIGS. 1A-1D and 2A-2F ) to pressure outlet 150 A, thereby coupling the pressure reservoir to material dispensing element 155 A (depicted by a phantom outline for simplicity's sake) to dispense flowable material, as indicated by the solid arrow. A secondary flow path 131 B is created between pressure outlet 150 B and bleed port 141 B, thereby ensuring that pressure outlet 150 B remains at a baseline pressure (e.g., atmospheric pressure) when not actively delivering material from material dispensing element 155 B.

Then, as diverter 130 is moved in the direction indicated by the solid arrow in FIG. 4B , a trigger feature 132 on diverter 130 can actuate optional pressure release valve 140 , thereby venting the pressure reservoir (and hence the pressure supplied to material dispensing element 155 A), as indicated by the dotted arrows. Note that in various other embodiments, pressure release valve 140 can be eliminated, such that the pressure reservoir is not vented when switching outlets, thereby allowing immediate application of pressure to the newly switched pressure outlet.

Note further that for exemplary purposes, pressure release valve 140 is depicted as a simple one-way check valve. However, as noted above, in various other embodiments, pressure release valve 140 can incorporate any pressure release mechanism. Note further that for exemplary purposes, triggering feature 132 is depicted as a raised element on diverter 130 that can actuate pressure release valve 140 . However, in various other embodiments, triggering feature 132 can be any system for actuating pressure release valve 140 , including a magnetic switch, a proximity sensor, and/or a mechanical linkage.

As switching is completed as shown in FIG. 4C , triggering feature 132 allows pressure release valve 140 to close, and the new positions of sealing elements 136 result in flow path 131 A connecting pressure reservoir outlet 111 to pressure outlet 150 B, thereby coupling the pressure reservoir to material dispensing element 155 B to dispense flowable material, as indicated by the solid arrow. A secondary flow path 131 C is created between pressure outlet 150 A and bleed port 141 B, thereby ensuring that pressure outlet 150 A remains at a baseline pressure to prevent unintended discharge from material dispensing element 155 A.

FIG. 5A shows another embodiment of material delivery system 100 (described with respect to FIGS. 1A-1D ) in which diverter 130 is an axially-rotatable element that defines a first flow path 131 A and a second flow path 131 B. Specifically, diverter 130 a cylindrical element positioned within housing 101 , with flow paths 131 A and 131 B formed as channels on the surface of the cylinder. The rotational orientation of diverter 130 , and hence, the positions of flow paths 131 A and 131 B, determines the particular interconnections between outlets 150 A and 150 B, pressure reservoir outlet 111 , and bleed ports 141 A and 141 B.

For example, in FIG. 5A , flow path 131 A connects pressure reservoir outlet 111 (the pressure reservoir itself is not shown for simplicity) to pressure outlet 150 A, thereby coupling the pressure reservoir to material dispensing element 155 A (depicted by a phantom outline for simplicity's sake) to dispense flowable material, as indicated by the solid arrow. Flow path 131 B connects pressure outlet 150 B and bleed port 141 B, thereby ensuring that pressure outlet 150 B remains at a baseline pressure (e.g., atmospheric pressure) when not actively delivering material from material dispensing element 155 B.

Then, as diverter 130 is rotated about its longitudinal axis as indicated in FIG. 5B , flow path 131 A connects with bleed port 141 A (while still connecting pressure reservoir outlet 111 to outlet 150 A), thereby venting the pressure reservoir (and hence the pressure supplied to material dispensing element 155 A) to the baseline pressure, as indicated by the dotted arrow.

Continuing to rotate diverter 130 as indicated in FIG. 5C eventually results in flow path 131 A being disconnected from pressure reservoir outlet 111 (although still connecting outlet 150 A to bleed port 141 A), while flow path 131 B disconnects from bleed port 141 B but connects pressure reservoir outlet 111 to outlet 150 B. As a result, material can be dispensed from material dispensing element 155 B in response to pressure generated within the pressure reservoir, while pressure outlet 150 A remains at the baseline pressure to prevent unintentional discharge from material delivery element 155 A.

After desired material dispensing from material delivery element 155 B, diverter 130 can be further rotated to cause flow path 131 B to connect with bleed port 141 B (while still connecting pressure reservoir outlet 111 to outlet 150 B), as shown in FIG. 5D . The pressure reservoir (and outlet 150 B at material delivery element 155 B) are therefore vented in preparation for switching output back to material delivery element 155 A. Note that while a continuous rotation mode of operation (i.e., rotating diverter 130 in a single direction to switch outputs) is described for exemplary purposes, in various other embodiments, output switching can be performed by rotating diverter 130 between particular angular orientations (i.e., rotating back and forth).

FIGS. 3A-3G show an exemplary use of material delivery system 100 in a kyphoplasty procedure. In FIG. 3A , cannulas 310 A and 310 B are positioned within a fractured vertebra 300 , thereby providing an access path to the target surgical location, which in this case is the cancellous bone structure 300 -C within vertebra 300 . Typically, cannulas 310 A and 310 B are docked into the exterior wall of vertebral body 300 (using either a transpedicular or extrapedicular approach) using a guide needle and/or dissector, after which a drill or other access tool (not shown) is used to create a path further into cancellous bone 300 -C. However, any other method of cannula placement can be used.

Next, cavity-creation tools such as inflatable bone tamps 320 A and 320 B are placed into cannulas 310 A and 310 B, respectively, to position expandable members (e.g., balloons) 321 A and 321 B, respectively, within cancellous bone 300 -C. Expandable members 321 A and 321 B are then expanded as shown in FIG. 3B to create cavities 325 A and 325 B, respectively, within cancellous bone 300 -C.

Inflatable bone tamps 320 A and 320 B are then removed and replaced with material delivery elements 155 A and 155 B, respectively, coupled to material delivery system 100 (as described with respect to FIGS. 2A-2E ) as shown in FIG. 3C . For exemplary purposes, material dispensing elements 155 A and 155 B are coupled to pressure outlets 150 A and 150 B, respectively, by flexible hydraulic lines (tubing) 156 A and 156 B. This enables delivery control from a distance, which beneficially allows the physician to perform the material delivery procedure from outside the fluoroscopic field generated during radioscopic visualization of vertebral body 300 . Note, however, that in various other embodiments, pressure outlets 150 A and 150 B can be coupled to material dispensing elements 155 A and 155 B, respectively, by more rigid structures.

For exemplary purposes, material dispensing elements 155 A and 155 B are depicted as including storage chambers 157 A and 157 B, respectively, and long, thin dispensing outlets (nozzles) 151 A and 151 B, respectively, that are sized to fit through cannulas 310 A and 310 B, respectively. Storage chambers 157 A and 157 B hold an amount of bone filler material that can be delivered to cavities 325 A and 3256 , respectively, via elongate nozzles 151 A and 151 B, respectively.

For exemplary purposes, diverter 130 is initially positioned to couple pressure reservoir 110 to material delivery element 155 A. However, diverter 130 can be switched to the opposite position (i.e., coupling pressure reservoir 110 to material delivery element 155 B) or can even be in the mid-point position (i.e., coupling pressure reservoir 110 to both material delivery elements 155 A and 155 B and opening release valve 140 ), before switching to a desired one of material delivery elements 155 A and 155 B.

To begin filling cavity 325 A, pressure source 120 is used to pressurize pressure reservoir 110 , thereby forcing bone filler material 305 from material dispensing element 155 A, as shown in FIG. 3D . In the embodiment shown, storage chamber 157 A includes a piston 153 A that expresses bone filler material 305 through delivery nozzle 151 A and into cavity 325 A in response to hydraulically-delivered pressure P 1 from pressure reservoir 110 .

Once a sufficient amount of bone filler material 305 is delivered to cavity 325 A, diverter 130 can be used to switch the output of material delivery system 100 . As described with respect to FIGS. 2C and 2D , initiating this switching process as shown in FIG. 3E can open pressure release valve 140 (via triggering feature 132 ) to vent pressure reservoir 110 to the predetermined baseline pressure PO (e.g., ambient pressure). In conjunction, flow path 131 of diverter couples both material dispensing elements 155 A and 1558 to pressure reservoir 110 , thereby ensuring that the flow of bone filler material from delivery nozzle 151 A is stopped and that no unintended flow of bone filler material occurs from delivery nozzle 151 B.

Upon completion of the switching operation of diverter 130 , material dispensing element 155 A is isolated from, and material dispensing element 1556 is coupled to, pressure reservoir 110 , as shown in FIG. 3F . Consequently, as pressure source 120 pressurizes pressure reservoir 110 anew, this new pressure P 2 only drives bone filler material 305 from delivery nozzle 325 B of material dispensing element 355 B. In this manner, bone filler material 305 can be delivered to vertebral body 300 in a controlled and user-friendly manner.

Note that a sequential two-step bone filler material delivery operation (i.e., fill cavity 325 A, and then fill cavity 325 B) is described for exemplary purposes only. In various other embodiments, cavities 325 A and 325 B can be filled in any order, using any number of discrete filling operations. For example, cavity 325 A could be partially filled via material dispensing element 155 A, diverter 130 could be used to switch the output of material delivery system 100 to material dispensing element 155 B to allow partial filling of cavity 325 B. Diverter 130 could then switch the output back to material dispensing element 155 A, to enable additional material delivery to cavity 325 A. The filling process could continue alternating between cavities 325 A and 325 B until a desired amount of bone filler material 305 is delivered to each.

Once the filling operation is complete, delivery nozzles 151 A and 151 B, and cannulas 310 A and 310 B are removed from vertebra 300 (and the patient's body) as shown in FIG. 3G . Upon hardening, bone filler material 305 provides structural support for vertebra 300 , thereby substantially restoring the structural integrity of the bone and the proper musculoskeletal alignment of the spine. In this manner, the pain and attendant side effects of a vertebral compression fracture can be addressed by the kyphoplasty procedure.

While various embodiments of the invention have been described above, it should be understood that they have been presented by way of example only, and not limitation. Where methods and steps described above indicate certain events occurring in certain order, those of ordinary skill in the art having the benefit of this disclosure would recognize that the ordering of certain steps may be modified and that such modifications are in accordance with the variations of the invention. Additionally, certain steps may be performed concurrently in a parallel process when possible, as well as performed sequentially as described above. Thus, the breadth and scope of the invention should not be limited by any of the above-described embodiments, but should be defined only in accordance with the following claims and their equivalents. While the invention has been particularly shown and described with reference to specific embodiments thereof, it will be understood that various changes in form and details may be made.