An apparatus includes a scaffold configured to be disposed in a bone. The scaffold is configured to move from a first configuration to a second configuration. The scaffold in the second configuration is expanded from the first configuration. A selectively-expandable actuator is configured to be removably disposed within the scaffold. The selectively-expandable actuator is configured to move at least a portion of the scaffold to the second configuration when the selectively-expandable actuator is moved to an expanded configuration. A shape of the selectively-expandable actuator is substantially the same as a shape of the scaffold when the selectively-expandable actuator and the scaffold are in the second configuration. The selectively-expandable actuator configured to be removed from the scaffold when in a collapsed configuration. The scaffold is configured to remain substantially in the second configuration after the scaffold has been expanded by the actuator.

BACKGROUND

The invention relates generally to expandable devices that can be inserted into a bone. More specifically, the invention relates to selectively-expandable bone scaffolds.

Small-tissue-insertion and -deployment tools allow access to the targeted tissue site through some minimally invasive procedures. When deployed within the targeted tissue site, such tools can assume enlarged, durable shapes. This allows cortical bone to be displaced in a desired manner and/or cavities to be created in cancellous bone without over-expansion, puncture, and/or abrasion of the structure. The tool can be left within the bone to provide additional support for the bone after expansion of the tool.

These known expandable tools can, for example, compact cancellous bone to fix a fracture, or to improve other osteoporotic and non-osteoporotic conditions of human and animal bones. These known devices, however, either lack sufficient directional control or fail to provide consistent compaction or distraction of the bone structure due to gaps in the structure of the tool.

Thus, a need exists for improvements in selectively-expandable structures that are disposable in bones.

SUMMARY OF THE INVENTION

An apparatus includes a scaffold configured to be disposed in a tissue (e.g., a bone, a vertebral bone, an intervertebral disc, etc.). The scaffold is configured to move from a first configuration to a second configuration. The scaffold in the second configuration is expanded from the first configuration. A selectively-expandable actuator is configured to be removably disposed within the scaffold. The selectively-expandable actuator is configured to move at least a portion of the scaffold to the second configuration when the selectively-expandable actuator is moved to an expanded configuration. A shape of the selectively-expandable actuator is substantially the same as a shape of the scaffold when the selectively-expandable actuator is in the expanded configuration and the scaffold is in the second configuration. The selectively-expandable actuator is configured to be removed from the scaffold when the selectively-expandable actuator is in a collapsed configuration. The scaffold is configured to remain substantially in the second configuration after the scaffold has been expanded by the actuator.

DETAILED DESCRIPTION

An apparatus includes a scaffold configured to be disposed in a tissue (e.g., a bone, a vertebral bone, an intervertebral disc, etc.). The scaffold is configured to move from a first configuration to a second configuration. The scaffold in the second configuration is expanded from the first configuration. A selectively-expandable actuator is configured to be removably disposed within the scaffold. The selectively-expandable actuator is configured to move at least a portion of the scaffold to the second configuration when the selectively-expandable actuator is moved to an expanded configuration. A shape of the selectively-expandable actuator is substantially the same as a shape of the scaffold when the selectively-expandable actuator is in the expanded configuration and the scaffold is in the second configuration. The selectively-expandable actuator is configured to be removed from the scaffold when the selectively-expandable actuator is in a collapsed configuration. The scaffold is configured to remain substantially in the second configuration after the scaffold has been expanded by the actuator.

The scaffold is configured to plastically deform when moved to the expanded configuration. Once the scaffold is deformed, its position is maintained within the body where positioned (i.e., a bone). Plastic deformation refers to a permanent change in shape and/or size of a material without fracture, produced by a stress sustained for a period of time beyond the elastic limit of the material.

The term “scaffold” is used herein to mean a deployable device that is configured to be disposed within a bone, such as a vertebra. The scaffold can optionally move a portion of the bodily structure in which it is disposed (e.g., cancellous bone within a vertebra). Regardless of whether the scaffold changed the position of the bodily structure upon deployment, the scaffold can maintain, or assist in maintaining, the shape and/or position of the bodily structure.

The scaffold is configured to remain substantially in its second configuration after the selectively-expandable actuator has been removed. The term “substantially” in this context refers to the fact that the scaffold may possibly undergo some insignificant amount of compression (e.g., change in shape and/or position) while remaining in the bone.

The term “selectively-expandable actuator” is used herein to mean an actuator that can be expanded and collapsed periodically for a period of time and/or randomly. Additionally, the actuator can be expanded intermittently and/or through varying degrees of expansion and collapsing. For example, the actuator need not be completely expanded or completely collapsed.

FIG. 1is a schematic cross-sectional view of a medical device10according to an embodiment of the invention. The medical device includes a scaffold20that is configured to be disposed in a bone (not illustrated). The scaffold20is configured to move between a first configuration illustrated as a solid line inFIG. 1and a second configuration illustrated as a dashed line inFIG. 1. The scaffold20is collapsed in the first configuration and is expanded in the second configuration.

A selectively-expandable actuator30is configured to be removably disposed within the scaffold20. The selectively-expandable actuator30is configured to move at least a portion of the scaffold20to the second configuration when the selectively-expandable actuator30is moved to its expanded configuration.

A shape of the selectively-expandable actuator30is substantially the same as a shape of the scaffold20when the selectively-expandable actuator30is in the expanded configuration and the scaffold20is in the second configuration. Additionally, the selectively-expandable actuator30and the scaffold20can be concentrically and/or coaxially aligned.

After the selectively-expandable actuator30has moved the scaffold20to the second configuration, the selectively-expandable actuator30can be returned to its collapsed configuration and removed from the scaffold20. The scaffold20is configured to remain substantially in the second configuration within the bone after the selectively-expandable actuator30has been removed. The selectively-expandable actuator30need only be collapsed a sufficient degree to be removed from the scaffold20. In other words, the collapsed configuration is any configuration that allows the selectively-expandable actuator30to be inserted into and/or removed from the scaffold20.

The scaffold20can be inserted into a body percutaneously and is inserted through the bone when the scaffold20is in the first configuration. After the scaffold20is moved to the second configuration, the scaffold20remains within the bone.

The scaffold20is plastically deformed when moved into the second configuration. In other words, the mechanical properties of the scaffold20change such that the scaffold20can not return to its initial configuration. The geometry of the scaffold20is permanently altered.

When the scaffold20is expanded (i.e., moved to its second configuration) in a vertebra, the scaffold20is configured to expand a volume in the cancellous bone of the vertebra. The volume can be created, for example, by compacting the cancellous bone and/or moving, and subsequently extracting, the cancellous bone or other biological material. The medical device10is able to compact bone by providing a force across the scaffold20while the scaffold is actuated. The scaffold20is moved apart by the expandable actuator30.

In some embodiments, the selectively-expandable actuator30includes a balloon. The balloon can be either symmetrical or asymmetrical about a longitudinal axis of the balloon. The balloon is configured to be expanded, for example, by a liquid and/or a gas.

The medical device10includes a shaft50, which is coupled to the scaffold20. The shaft50is configured to be moved in the direction away from the scaffold20indicated by arrows X-X inFIG. 1. The shaft50is used to insert the medical device10into the bone and is removed after expansion of the scaffold20to the second configuration. In some embodiments, shaft50can be a cannula defining a passageway or working channel55.

The scaffold20can be removably coupled to the shaft50. Prior to deployment of the scaffold20, the shaft50can be used as a filler tube. Filler material can be injected through the interstices of the scaffold20for placement within the vertebra (e.g., adjacent to the cancellous bone). The working channel55of the shaft50can also be used as a passageway for the use of additional working tools.

Shaft60that is configured to be removably inserted within passageway55defined by shaft50. To remove the selectively-expandable actuator30from within the scaffold20, shaft60can be withdrawn from the medical device10in the direction illustrated by arrow Z.

FIGS. 2aand2bare perspective views of a medical device10′ including a bone scaffold20′ according to an embodiment of the invention. As illustrated inFIG. 2, the scaffold20′ includes multiple oval shaped slots15along its length. The shape of each slot15affects the shape of the scaffold20′ when the scaffold20′ is in the expanded configuration. The slots15can be either symmetrical or asymmetrical about the circumference of the scaffold20′. As the actuator (not shown inFIG. 2aor2b) expands, the scaffold20′ expands within the bone. In some embodiments, the scaffold20′ and actuator (not shown) compact cancellous bone as the scaffold and the actuator move to their respective expanded configurations.

The scaffold20′ is removably coupled to a shaft50′ which can be used as, for example, a cannula. Once the scaffold20′ is expanded, the shaft50′, is removed from the scaffold20′, leaving the scaffold20′ in the bone.

FIG. 3is a perspective view of a medical device10″ including a bone scaffold20″ , and an associated shaft50″ , according to a further embodiment of the invention. The scaffold20″ includes multiple wires22disposed about the circumference of scaffold20″. In some embodiments, the wires22are expanded into cancellous bone of a vertebra by an actuator, such as, for example, a balloon actuator. The scaffold20″ can then be moved (e.g., rotationally and/or laterally) such that the wires cut the cancellous bone and the cancellous bone is removed, thereby modifying a volume in the vertebra created by medical device10″.

FIGS. 4-6illustrate a side view of the medical device10′ ofFIG. 2in various configurations.FIG. 4is a side view of medical device10′ in the first configuration. As discussed above, the medical device10′ is in its first configuration prior to being inserted into a bone, such as a vertebra. In some embodiments, the selectively-expandable actuator30′ is disposed within the scaffold20′ when inserted into the bone, the scaffold20′ having multiple slots15′ formed along its length as shown inFIG. 4. In other embodiments, the scaffold20′ can be inserted into the bone first and then the selectively-expandable actuator30′ can be inserted through the passageway defined by shaft50′ and into an interior of scaffold20′.

FIGS. 5aand5bare side views of medical device10′ in the second configuration with the selectively-expandable actuator30′ disposed within the scaffold20′. As the selectively-expandable actuator30′ expands the scaffold20′, a volume is defined within the cancellous bone disposed about medical device10′. In some embodiments, the cancellous bone is compacted by the actuator30′ and the scaffold20′.

FIG. 6is a side view of the apparatus10′ in its second configuration after the selectively-expandable actuator30′ has been removed from the scaffold20′. Once the selectively-expandable actuator30′ has been removed from the scaffold20′, the shaft50′ is removed from the scaffold20′, and the scaffold20′ remains in the bone.

The shaft50′ can be removably coupled to the scaffold20′ by known connectors. For example, the shaft50′ can be coupled to the scaffold20′ using a threaded connector, a break-away connector, a lock-and-key connection, etc. Any suitable connection device is appropriate, provided the shaft50′ can be removed from the scaffold20′ once the scaffold20′ is positioned and expanded in the bone.

FIG. 7is a side view of a portion of a scaffold20′″ according to another embodiment of the invention when the scaffold20′″ is in its first configuration.FIG. 8is a side view of the portion of the scaffold20′″ illustrated inFIG. 7in its second configuration. In some embodiments, slits25are defined along the scaffold20′″ such that when scaffold20′″ is expanded by an actuator (not illustrated) as discussed above, scaffold20′″ moves to the second configuration illustrated inFIG. 8. In the second configuration, multiple gaps27are formed between adjacent portions of the scaffold20′″.

As illustrated inFIG. 7, openings17are defined at an end of each slit25. As the scaffold20′″ moves to the second configuration, the scaffold20′″ expands uniformly along its length. The longer the scaffold20′″, the greater the potential change in diameter within the stress limits of the material used to make the scaffold20′″. For example, if a material can tolerate three degrees of separation at the openings17, a longer scaffold20′″ would result in a larger diameter change for the same three degrees of tolerance.

In an alternative arrangement (not shown) multiple scaffolds20′″ can be oriented concentrically (i.e., one inside the other) with respect to one another. Additionally, the concentrically-oriented scaffolds20′″ can be rotated with respect to one another such that the slits17for one scaffold20′″ are out of phase (i.e., not completely overlapping) with the slits17for the other scaffold20′″. In such a configuration, when the scaffolds20′″ are expanded, the size of the gaps27collectively are reduced and the strength of the scaffold combination (i.e., the inner scaffold20′″ and the outer scaffold20′″) is increased. The scaffolds20′″ can be welded in place to maintain their relative position.

When the scaffolds20′″ are oriented concentrically and then expanded, portions of the inner scaffold20′″ expand outwardly, while portions of the outer scaffold20′″ collapse inwardly. The adjacent portions of each scaffold20′″ substantially inhibit the remaining scaffold20′″ from collapsing under external pressure. Such scaffolds20′″ can be formed, for example, from shape-memory material that is inserted in a collapsed configuration and expanded after insertion into a vertebral body.

FIGS. 9-11illustrate a medical device100that includes a scaffold200having a first portion210and a second portion220that are collectively movable between a first collapsed configuration (seeFIG. 10) and a second expanded configuration (seeFIG. 11). The first portion210and the second portion220are physically distinct. The first portion210is configured to contact the second portion220when the scaffold200is in its first configuration. When the scaffold200is moved to its second configuration, the first portion210is spaced apart from the second portion220as illustrated inFIG. 11.

An actuator130is removably coupled to the scaffold200. The actuator130is configured to move the scaffold200from the first configuration to the second configuration. A sleeve300is disposed around the scaffold200. The sleeve300is configured to bias the first portion210of the scaffold200towards the second portion220of the scaffold200. In some embodiments, the sleeve is substantially elastic. When outward pressure of the actuator130is sufficient, the outward pressure can overcome the elasticity of the sleeve300. The properties of the sleeve300may be varied such that the firs portion210of the scaffold200expands at a different rate than the second portion220of the scaffold200when actuated. In other words, the scaffold200can be expanded in an anisotropic manner.

Medical device500, according to an embodiment of the invention is illustrated inFIGS. 12 through 14.FIG. 12is a side cross-sectional view of the medical device500in its first configuration.FIG. 13is a side cross-sectional view of the medical device500as illustrated onFIG. 12in its second configuration.FIG. 14is a perspective view of medical device500according to an embodiment of the invention in its second configuration.

As illustrated inFIGS. 12 through 14, the scaffold520has a substantially spiral shape. As illustrated inFIGS. 12 and 13, when the selectively-expandable actuator530is moved to its second configuration, only a portion522of the scaffold520that is contacted by the actuator530is moved to a second configuration and the portion524of the scaffold520not contacted by the actuator does not move to the second configuration.

The scaffold520can be either elastically or plastically deformed. Additionally, the selectively-expandable actuator530can be either uniformly expandable or non-uniformly expandable such that the shape of the scaffold520in its second configuration may vary along its length.

Conclusion

While the invention has been particularly shown and described with reference to embodiments thereof, it will be understood by those skilled in art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.

For example, although the selectively-expandable actuators30,30′,130,530are described as including a single balloon, in alternative embodiments multiple independent actuators may be provided between within the scaffold. For example, the actuator(s) may include multiple chambers that are independently actuated to permit an isotropic deployment of the scaffold.

Although the scaffold is described without reference to specific materials, the scaffold can be made of any material sufficient to be inserted into body tissue and modify the volume of the tissue. For example, the scaffold can be made of Nitinol or stainless steel.

While the selectively-expandable actuator30is described above as being coupled to a separate shaft60, in alternative embodiments the actuator30can be coupled to the same shaft50as the scaffold20. In such a configuration, when the shaft50is uncoupled and removed from the scaffold20, the actuator30would also be removed.

Additionally, although the selectively-expandable actuator30is primarily described as a balloon-type actuator, selectively-expandable actuator30can be any type of mechanical actuator configured to expand the scaffold20from within the scaffold20. For example, the actuator can be a laterally expandable device including laterally extending projections that are configured to engage the scaffold20to move it to its expanded configuration. In other embodiments, the mechanical actuator can cause the expandable scaffold to be biased to have a substantially greater resistance to retrograde axial motion than to anterograde motion.

Although the scaffold20is described as being substantially cylindrical in the first configuration, in alternative embodiments, any shape sufficient to be modified to an expanded configuration to change the volume of tissue around the scaffold can be used. For example, the scaffold can be triangular, hexagonal, octagonal, etc.

Although removal of the actuator after expanding the scaffold is disclosed, in alternative embodiments, the actuator can remain in place within the scaffold, detach from the shaft to which it is attached and remain in the scaffold within the vertebra. In some embodiments, bone filler material may be inserted into the void created within the vertebra adjacent the scaffold.

Although described separately with respect to the various embodiments above, features of the disclosed embodiments may be interchangeably associated.