Needle for directional control of the injection of bone cement into a vertebral compression fracture

A needle for use in a surgical procedure includes an outer cannula including a shaft portion having a side wall and an end wall. A first aperture extends through the side wall of the outer cannula, and a second aperture extending through the end of the outer cannula. The needle also includes an inner cannula that is disposed within the outer cannula and includes a shaft portion having a bore extending therethrough. The inner cannula is selectively movable relative to the outer cannula between a first orientation and a second orientation. In the first orientation, communication is provided between the bore of the inner cannula and a first external region that is located adjacent to the second end of the outer cannula. In the second orientation, communication is provided between the bore of the inner cannula and a second external region that is located adjacent to the second end of the outer cannula.

BACKGROUND OF THE INVENTION

This invention relates in general to the field of orthopedic surgery including, more specifically, the field of spinal surgery. In particular, this invention relates to an improved structure for a needle that can provide selective directional control of the injection of a bone cement or other material into a fractured bone, such as a vertebra of a spine, during a spinal surgical procedure.

A compression fracture is a common fracture of a vertebra of the spine. In a typical compression fracture, the vertebra has suffered a crush or wedging injury. Vertebral compression fractures are common, especially in older adults who suffer from osteoporosis. Traditional conservative treatment includes bed rest, pain control, and physical therapy. For those patients who do not respond to conservative treatment, interventional procedures such as kyphoplasty and vertebroplasty can be considered. During a kyphoplasty procedure, a void is created within the fractured vertebra by initially inflating a balloon therein, then injecting a bone cement material under a relatively low pressure into the void. During a vertebroplasty procedure, a relatively high viscosity bone cement material is injected directly into the fractured vertebra without the initial creation of a void by balloon inflation.

In both of these procedures, the bone cement material may be injected into the fractured vertebra using a vertebral needle that can facilitate the directional flow of bone cement material to a desired location, thus improving the fill of the bone cement material within the vertebra. Most currently available vertebral needles allow the bone cement material to be injected either only (1) axially straight through a hole provided at the tip of the vertebral needle or (2) radially sideways through a hole provided in the sidewall of the vertebral needle. Thus, to optimize the control of the flow of the bone cement material into the vertebra, both of the two known types of the vertebral needles need to be used during the course of the surgical procedure. However, the intra-operative changing of the vertebral needles is relatively difficult and time consuming. Thus, it would be desirable to provide an improved structure for a needle that can provide selective directional control of the injection of a bone cement or other material into a fractured bone, such as a vertebra of a spine, during such a spinal surgical procedure.

SUMMARY OF THE INVENTION

This invention relates to an improved structure for a needle that can provide selective directional control of the injection of a bone cement or other material into a fractured bone, such as a vertebra of a spine, during a spinal surgical procedure. The needle includes an outer cannula including a shaft portion having a side wall and an end wall. A first aperture extends through the side wall of the outer cannula, and a second aperture extending through the end of the outer cannula. The needle also includes an inner cannula that is disposed within the outer cannula and includes a shaft portion having a bore extending therethrough. The inner cannula is selectively movable relative to the outer cannula between a first orientation and a second orientation. In the first orientation, communication is provided between the bore of the inner cannula and a first external region that is located adjacent to the second end of the outer cannula. In the second orientation, communication is provided between the bore of the inner cannula and a second external region that is located adjacent to the second end of the outer cannula.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring now to the drawings, there is illustrated inFIG. 1three vertebrae10,11, and12of a portion of a human spine. The three vertebrae10,11, and12may be located in any region of the human spine, but typically are located in the thoracic and lumbar regions. In the illustrated embodiment, the upper vertebra10and the lower vertebra12are undamaged, while the intermediate vertebra11has experienced a compression fracture as shown at11a. As a result of such compression fracture11a, the intermediate vertebra11can become collapsed between the upper vertebra10and the lower vertebra12, which can cause pain or an abnormal curvature of the spine. Although this invention will be described and illustrated in the context of repairing the compression fracture11aof the intermediate vertebra11, it will be appreciated that this invention may be practiced in connection with any other desired surgical procedure and for any other desired purpose.

A vertebral needle, indicated generally at20, is provided to treat the vertebral compression fracture11aof the intermediate vertebra11. As shown inFIG. 1, the vertebral needle20can be inserted into the intermediate vertebra11such that an end thereof is disposed within or adjacent to the region of the compression fracture11a. As will be explained in detail below, the vertebral needle20is adapted to facilitate the injection of a convention bone cement or other material into the region of the compression fracture11aduring an interventional procedure, such as kyphoplasty and vertebroplasty, to quickly and effectively ameliorate the condition.

The structure of the vertebral needle20is illustrated inFIGS. 2 through 7. As best shown inFIG. 2, the vertebral needle20includes an outer cannula, indicated generally at21, having a head portion22and a shaft portion23. The illustrated head portion22is generally hollow and cylindrical in shape and has an axially extending bore22aprovided therein that defines an inner surface. However, the head portion22of the outer cannula21can have any desired shape. The illustrated shaft portion23is also generally hollow and cylindrical in shape and has an axially extending bore23aprovided through a side wall therein having an inner surface that defines an interior space. However, the shaft portion23of the outer cannula21can have any desired shape. The inner surfaces of the bores22aand23aof the head portion22and the shaft portion23, respectively, are preferably axially aligned, although such is not required. In the illustrated embodiment, the head portion22and the shaft portion23of the outer cannula21are formed from a single piece of material, although such is not required. The head portion22and the shaft portion23may be formed from any desired material or combination of materials, such as titanium, stainless steel, cobalt-chrome, or any other suitable biomaterial.

The head portion22of the outer cannula21is provided at a first end of the shaft portion23thereof. A second opposite end of the shaft portion23terminates in an end wall24that closes the bore23aformed therethrough. In the illustrated embodiment, the end wall24has an outer surface24athat is tapered toward a point. However, the end wall24of the outer cannula21may have any desired shape. First and second apertures25and26are provided in the second end of the shaft portion23. The first aperture25extends axially through the end wall24and provides communication between the bore23aand an external region that is located axially adjacent to the second end of the outer cannula21. The second aperture26extends radially through the side wall of the shaft portion23and provides communication between the bore23aand an external region that is located radially adjacent to the second end of the outer cannula21. Additionally, a recessed area27is provided on the inner surface of the bore23aadjacent to the first aperture25. The purposes for the first aperture25, the second aperture26, and the recessed area27will be explained below.

As shown inFIG. 2, the vertebral needle20also includes an obturator, indicated generally at30, having a head portion31and a shaft portion32. The illustrated head portion31is generally cylindrical in shape. However, the head portion31of the obturator30can have any desired shape. The illustrated shaft portion32is also generally cylindrical in shape and defines an outer surface. However, the shaft portion32of the obturator30can have any desired shape. The obturator30is supported on the outer cannula21for movement relative thereto. In the illustrated embodiment, the outer surface of the shaft portion32of the obturator30is supported for sliding movement on the inner surface of the bore23aof the shaft portion23of the outer cannula21. The obturator30has a tip portion33that, in the illustrated embodiment, includes a tapered end surface33a. In the illustrated embodiment, the head portion31and the shaft portion32of the obturator30are formed from a single piece of material, although such is not required. The head portion31and the shaft portion32may be formed from any desired material or combination of materials, such as titanium, stainless steel, cobalt-chrome, or any other suitable biomaterial.

The obturator30can be located in an installation position (illustrated inFIG. 2) relative to the outer cannula21. In this installation position, the head portion31of the obturator30abuts the head portion22of the outer cannula21. In this manner, the obturator30can be positively positioned relative to the outer cannula21. When the obturator30is located in the installation position, the tip portion33of the obturator30extends through the first aperture25provided through the end wall24of the outer cannula21. Thus, the tip portion33blocks the first aperture25, thereby preventing communication between the bore23aand the external region that is located axially adjacent to the second end of the outer cannula21. Preferably, the tapered end surface33aof the tip portion33of the obturator30is generally co-extensive with the outer surface24aof the end wall24of the outer cannula21such that the outer cannula21and the obturator30cooperate to present a pointed tip at the second end of the vertebral needle20. The purpose for this pointed tip will be explained below. Additionally, when the obturator30is located in the installation position shown inFIG. 2, the tip portion33blocks the second aperture26, thereby preventing communication between the bore23aand the external region that is located radially adjacent to the second end of the outer cannula21. The purpose for such blockage will be explained below.

As shown inFIGS. 3,6, and7, the obturator30can be removed from the outer cannula21, and an inner cannula, indicated generally at40, and be disposed in its stead. The inner cannula40includes a head portion41and a shaft portion42. The illustrated head portion41is generally hollow and cylindrical in shape and has an axially extending bore41aprovided therein that defines an inner surface. However, the head portion41of the inner cannula40can have any desired shape. The illustrated shaft portion42is also generally hollow and cylindrical in shape and has an axially extending bore42aprovided therein having an inner surface that defines an interior space. However, the shaft portion42of the inner cannula40can have any desired shape. The inner surfaces of the bores41aand42aof the head portion41and the shaft portion42, respectively, are preferably axially aligned, although such is not required. In the illustrated embodiment, the head portion41and the shaft portion42of the inner cannula40are formed from a single piece of material, although such is not required. The head portion41and the shaft portion42may be formed from any desired material or combination of materials, such as titanium, stainless steel, cobalt-chrome, or any other suitable biomaterial.

The head portion41of the inner cannula40is provided at a first end of the shaft portion42thereof. A second opposite end of the shaft portion42terminates in an end wall43that closes the bore42aformed therethrough. One or more spacers44may be provided on the outer surface of the end wall43. In the illustrated embodiment, four equally sized and shaped spacers44extend axially from the end wall43of the inner cannula40. However, the spacers44may be provided having any desired shape or combination of shapes. An aperture45is provided through a side wall in the second end of the shaft portion42of the inner cannula40. The aperture45extends radially through the side wall of the shaft portion42and provides communication between the bore42aand an external region that is located radially adjacent to the second end of the inner cannula40. The spacers44engage the end wall24of the outer cannula21so as to maintain a space between the end wall43of the inner cannula40and the end wall24of the outer cannula21.

As best shown inFIGS. 6, and7, the inner cannula40can be selectively positioned in first and second orientations relative to the outer cannula21.FIG. 6shows the inner cannula40positioned in the first orientation relative to the outer cannula21. In this first orientation, the aperture45that extends radially through the side wall of the shaft portion42of the inner cannula40is aligned with the second aperture26that extends radially through the side wall of the shaft portion23of the outer cannula21. This alignment of the apertures45and26provides communication between the bore42aprovided within the shaft portion42of the inner cannula40and the external region that is located radially adjacent to the second end of the outer cannula21, as shown by the arrow51inFIG. 6. At same time, the end wall43of the inner cannula40prevents communication between the bore42aprovided within the shaft portion42of the inner cannula40and the external region that is located axially adjacent to the second end of the outer cannula21.

FIG. 7shows the inner cannula40positioned in the second orientation relative to the outer cannula21. In this second orientation, the aperture45that extends radially through the side wall of the shaft portion42of the inner cannula40is aligned with the recessed area27that is provided in the side wall of the shaft portion23of the outer cannula21. This alignment of the aperture45and the recessed area27provides communication between the bore42aprovided within the shaft portion42of the inner cannula40and the external region that is located axially adjacent to the second end of the outer cannula21, as shown by the arrow52inFIG. 7. At same time, the side wall of the shaft portion42of the inner cannula40prevents communication between the bore42aprovided within the shaft portion42of the inner cannula40and the external region that is located radially adjacent to the second end of the outer cannula21.

The inner cannula40can be selectively positioned in first and second orientations relative to the outer cannula21quickly and easily by rotating the inner cannula40relative to the outer cannula21. If desired, one or more indicia (not shown) may be provided on either or both of the inner cannula40and the outer cannula21to provide a visual indication of when the first and second orientations have been achieved. Alternatively, one or more conventional detents, stops, or other structures (not shown) may be provided on either or both of the inner cannula40and the outer cannula21to provide a tactile indication of when the first and second orientations have been achieved.

The method of operation of the vertebral needle20will now be explained. Initially, the obturator30is installed within the outer cannula21and positioned in the installation position illustrated inFIG. 2. As mentioned above, when the obturator30is located in the installation position, the tip portion33of the obturator30extends through the first aperture25provided through the end wall24of the outer cannula21. Additionally, the tip portion33of the obturator30blocks the second aperture26provided through the side wall of the shaft portion23of the outer cannula21, thereby preventing communication between the bore23aand the external region that is located radially adjacent to the second end of the outer cannula21. The assembly of the outer cannula21and the obturator30can then be inserted through a relatively small incision until the tip portion33of the obturator30engages a desired location on the surface of the intermediate vertebra11.

As mentioned above, the tapered end surface33aof the tip portion33of the obturator30is preferably co-extensive with the outer surface24aof the end wall24of the outer cannula21such that the outer cannula21and the obturator30cooperate to present a pointed tip at the second end of the vertebral needle20. This pointed tip is adapted for impaction into the desired location by utilizing a conventional tool, such as an orthopedic mallet. The precise location where the tip portion33of the obturator30engages the surface of the intermediate vertebra11is usually determined using conventional fluoroscopic or other imaging or navigational techniques. The assembly of the outer cannula21and the obturator30is continued to be inserted until the tip portion33of the obturator30is disposed within the compression fracture11awithin the intermediate vertebra11.

Next, the obturator30is removed from the outer cannula21, and the inner cannula40is inserted within the outer cannula21, as shown inFIG. 3. As discussed above, the inner cannula40can be selectively positioned in either of the first and second orientations relative to the outer cannula21. Such relative positioning provides selective directional control of the injection of a bone cement or other material into the compression fracture11awithin the intermediate vertebra11. To accomplish this, a quantity of the bone cement or other material is initially inserted within the vertebral needle20through the bore41aprovided in the head portion41of the inner cannula40. Such bone cement or other material can then moved through the shaft portion42of the inner cannula40in any conventional manner, such as under pressure or by means of a conventional plunger (not shown). A preferred method would include a threaded or otherwise secure locking mechanism that would allow attachment of a cement containing device (not shown) to the delivery cannula. The cement containing device may come in the form of currently available threaded syringe or other similar mechanisms that facilitate controlled extrusion of the cement material.

When the inner cannula40positioned in the first orientation relative to the outer cannula21shown inFIG. 6, the bone cement or other material will follow the path indicated by the arrow51into the external region that is located radially adjacent to the second end of the outer cannula21. When the inner cannula40positioned in the second orientation relative to the outer cannula21shown inFIG. 7, the bone cement or other material will follow the path indicated by the arrow52into the external region that is located radially adjacent to the second end of the outer cannula21. Thus, the vertebral needle provides selective directional control of the injection of the bone cement or other material quickly and easily.

In the illustrated embodiment, the outer cannula21and the inner cannula40are structured in such a manner that the bone cement or other material pass outwardly from either, but not both, of the first and second apertures25and26. However, it will be appreciated that the outer cannula21and the inner cannula40could be structured to provide an intermediate relative orientation wherein the bone cement or other material could pass outwardly from both of the first and second apertures25and26simultaneously. Also, it will be appreciated that either or both of the outer cannula21and the inner cannula40can be provided with a greater number of apertures to provide additional selective relative positioning for greater directional control of the injection of the bone cement or other material.