Patent Application
20120059382
Not Applicable
Not Applicable
1. Technical Field
The present invention relates to an improved guide assembly to be used in the reconstruction of a ligament as well as methods for using the assembly. The present invention also relates to an improved ligament reconstruction guide assembly and methods for locating tibial and femoral bone tunnels in the reconstruction of anterior and posterior cruciate ligaments.
2. Background
Examples of guides to create tibial tunnels for anterior cruciate ligament (ACL) reconstruction include those described and disclosed in U.S. Pat. No. 6,254,605 to Howell, Stephen entitled “Tibial Guide” issued on Jul. 3, 2001 and U.S. Pat. No. 5,300,077 to Howell, Stephen entitled “Methods and instruments for ACL reconstruction” issued on Apr. 5, 1994 both of which are herein incorporated by reference in their entirety. These disclosures describe assemblies and methods for ACL bone tunnel creation from the front, anterior position of the knee.
Similarly, publication WO2007107697, published Sep. 27, 2007 for PCT application PCT/GB2007/000767 filed Mar. 5, 2007 and US publication US20090171355, published Jul. 2, 2009 for U.S. application Ser. No. 12/225,460 filed Mar. 5, 2008 to Andrew AMIS et al., both publications of which are incorporated by reference in their entirety, disclose a guide for ACL repair.
In one example embodiment of a guide assembly for locating a tunnel position on an attachment surface of a bone for a joint ligament reconstruction, the guide assembly comprises a reference element, a cannulated guide with at least one longitudinal bore having at least one longitudinal axis and the longitudinal axis being aligned relative to the reference element, a bracket connecting the reference element and the cannulated guide and the bracket having a means to align the longitudinal axis relative to the reference element positioned from a posterior position to a bone. In some embodiments, the means to provide the reference may be a footprint target tip to position an attachment site for single or double bundle ligament reconstruction procedure. In some embodiments, the means to provide the reference can be positioned from an anterior position to the bone.
In one example embodiment of a guide assembly for locating a tunnel position on an attachment surface of a bone for a joint ligament reconstruction, the guide assembly comprises a reference element having a footprint target tip, the footprint target tip having a plurality of apertures, at least one cannulated guide having a longitudinal bore defining a longitudinal bore axis, a bracket to align the longitudinal bore of the cannulated guide relative to the plurality of apertures and the bracket connecting the referent element and the cannulated guide whereby the reference element can be positioned from a posterior position to the bone. In some embodiments, the bracket is an adjustable curved bracket connecting the reference element and the cannulated guide whereby the footprint target tip can be positioned on the bone from a posterior position to the bone and the cannulated guide can be positioned anterior to the bone.
In one example embodiment of the guide assembly for locating a tunnel position on an attachment surface of a bone for a joint ligament reconstruction comprises a reference element having a footprint target tip having a plurality of apertures, at least one cannulated guide having a longitudinal bore defining a longitudinal bore axis and a bracket to align the longitudinal bore of the cannulated guide relative to the plurality of apertures whereby the reference element can be positioned from a anterior position to the bone. In some embodiments, the bracket is an adjustable curved bracket connecting the reference element and the cannulated guide whereby the footprint target tip can be positioned on the bone from an anterior position to the bone and the cannulated guide can be positioned anterior to the bone.
In some embodiments, the plurality of apertures comprises at least a first, second and third aperture, each aperture being generally aligned serially on the footprint target tip with the second aperture being positioned between the first and the third aperture, each aperture having a center with each center offset by a predetermined separation and the predetermined separation being within an inclusive range of about two (2) to six (6) millimeters between the second center and the first and between the second center and the third center whereby the alignment of the second aperture and the cannulated guide locates a tibial bone tunnel position for a single bundle ACL replacement procedure and the alignment of the first and the third aperture and the cannulated guide locates the tibial bone tunnel positions for a multi bundle ACL replacement procedure.
In some embodiments, the footprint target tip comprises a flattened lower surface configured to nest with a tibial plateau of an intercondylar notch of the bone for an ACL replacement procedure.
In some embodiments, the footprint target tip comprises a flattened lower surface configured to nest with a roof surface of a femoral intercondylar notch of the bone for an ACL replacement procedure.
In some embodiments, the footprint target tip comprises a flattened lower surface configured to nest with a roof surface of a femoral intercondylar notch of the bone for a PCL replacement procedure.
In some embodiments, the plurality of apertures comprises at least a first, second and third aperture, each aperture being generally aligned serially on the footprint target tip with the second aperture being positioned between the first and the third aperture, each aperture having a center and each center offset by a predetermined separation and the predetermined separation being within an inclusive range of about two (2) to six (6) millimeters between a second center and a first and a third center whereby the alignment of the second aperture and the cannulated guide locates a tibial bone tunnel position for a single bundle ACL replacement procedure and the alignment of the first and the third aperture and the cannulated guide locates the tibial bone tunnel positions for a multi bundle ACL replacement procedure.
In one example embodiment of a method for locating a tunnel position on an attachment surface of a bone for a joint ligament reconstruction, the method comprises the steps of positioning a reference element having a footprint target tip posterior on a tibia through a posterior entry portal to locate a tibia tunnel exit point and positioning a distal end of at least one cannulated guide on the tibia to locate at least one tibial tunnel position for at least one tibial bone tunnel. In some embodiments, the step of positioning the reference elements comprises positioning the footprint target tip having a first aperture for locating an anteromedial bundle tunnel position and a second aperture for locating a posterolateral bundle tunnel position and the step of positioning the distal end of at least one cannulated guide comprises positioning the distal end of a first cannulated guide for locating an anteromedial bundle tunnel position and a second cannulated guide for locating a posterolateral bundle tunnel position whereby the at least one tibial tunnel position comprises an anteromedial bundle tunnel position and a posterolateral bundle tunnel position. In some embodiments, the reference element is positioned from an anterior entry portal.
In order that the manner in which the above-recited and other advantages and features of the invention are obtained, a more particular description of the invention briefly described above will be rendered by reference to specific embodiments thereof which are illustrated in the appended drawings. Understanding that these drawings depict only typical embodiments of the invention and are not therefore to be considered to be limiting of its scope, the invention will be described and explained with additional specificity and detail through the use of the accompanying drawings in which:
A ligament reconstruction guide assembly and methods for use will now be described in detail with reference to the accompanying drawings. It will be appreciated that although embodiments are described for use with ligament reconstruction, it is understood that the methods and systems described can be use for use in similar medical procedures where the positioning of tunnels, holes or other portals must be carefully placed. Notwithstanding the specific example embodiments set forth below, all such variations and modifications that would be envisioned by one of ordinary skill in the art are intended to fall within the scope of this disclosure.
Embodiments of this invention recognize the benefits that are available by positioning the ligament reconstruction guide assembly from either posterior or anterior positions to the knee. By positioning the target tip of the assembly from a posterior position, it has been found that proper tunnel locations can be made more easily on the surgical table which is an environment where space and time to act are limited. Positioning the target tip of the assembly from an anterior position can also provide accurate tunnel positioning for certain reconstruction procedures.
Embodiments of this invention also relate in part to advancing the art of single and double-bundle reconstruction surgery by recognizing that it is important to locate the bundle attachment sites in order to be able to properly guide the surgeon to create the correct tunnel sites. Embodiments of this invention provide several different systems for accurately locating the bundle attachment points in single and double-bundle procedures in ACL and PCL reconstructions. In particular, these systems enable accurate positioning of ACL and PCL attachment sites from a posterior or anterior position as well as attachment sites for either single of double bundle procedures. This provides a greater degree of flexibility, accuracy and reproducibility than with currently available instruments.
One embodiment of the ligament reconstruction guide assembly 100, as shown in
One embodiment of the bracket 160, as shown in
The rod bracket arm 270 has a connection means in its distal end to receive and connect to the distal end of the reference element. In
The guide bracket arm 280 has a connection means in its distal end to receive and connect to the cannulated guide 240. This connection means is positioned to allow proper alignment of the cannulated guide 240 with respect to the reference element 220. In the embodiment shown in
The bore 284 in the guide bracket arm 280 is also sized to receive other elements used in ligament reconstruction procedures. These other elements include but are not limited to cannulated reamers, coring drill bits, guide pins, collars and other similar instruments used in creating bone tunnels. The bore 284 has a longitudinal axis that aligns with the longitudinal axis of the cannulated guide 240 when received and other elements to ensure proper alignment of these elements with the reference element 220. The internal size of the bore 284 is also sized to closely fit the outside dimension of the received elements to minimize movement in the bore and therefore the deviation of their longitudinal axes.
One embodiment of the reference element 220 is an elongated rigid rod 222 having a target tip 224 at its distal end. The reference element 220 is attached at its proximal end 226 to the free distal end of the rod bracket arm 270. The target tip 224 is positioned inside the radial opening of the curve of the bracket so that it is generally positioned at the central radial point of the arched bracket. Although not necessary, the embodiment in
The reference element 220 is made of a rigid surgical material such as but not limited to but not limited to titanium, stainless steel, nitinol, metal alloys, plastics or other suitable synthetic materials. The length and diameter of the reference element is sized to provide a small profile in the patients' body when used. Suitable dimensions for illustration, and not for limitation include the reference element having a length ranging from about 4 to 5 inches and more preferably about 4.5 inches and a diameter ranging from about 0.17 to 0.2 inches and more preferably 0.187 to 0.188 inches tapering to a point at its distal tip. For reference elements with a bend, the bend can be any angle that helps the user position the distal tip of the element. For illustration purposes and not for limitation, for embodiments of the reference elements with a bend, the inner angle of the bend in the reference element can be about 100-170 degrees and in one preferred embodiment, about 130 degrees.
In an embodiment of the reference element, a shield is also provided to help prevent the insertion of elements through the cannulated guide beyond the shield. The shield can be an enlarged portion of the target tip or is may be a portion of the reference element separate from the target tip such as a generally flat plate. It is also contemplated that embodiments of the assembly provide for the target tip to be positioned relative to a radial center of the assembly, and this shield may be placed at that radial center. These types of embodiments will allow positioning of the assembly with the target tip while the cannulated guide allows guide pins to be inserted and the shield prevents the guide pin from damaging tissues in the knee beyond the shield.
Referring to the embodiment in
The cannulated guide 240 is a rigid elongated cylinder with proximal end 242, a distal end 244 and a longitudinal bore axis running down a longitudinal bore 246 of the cannulated guide. The distal end 244 of the guide 240 can be, but need not be serrated. Serrated edges help secure the cannulated guide on bone during surgery and can help bore into the bone when necessary. The proximal end 242 of the guide 240 can be, but need not be an enlarged portion 248. The longitudinal bore 246 extends through the length of the cannulated guide 240 and is large enough to allow surgical tools such as but not limited to guide pins, drill bits and other tools to be received through the hollow center. The length and diameter of the cannulated guide 240 are sized to provide a suitable length such that the user can position the distal end 244 of the guide on or in the patient's bone while also safely inserting a guide wire or guide pin to position the tunnel. Diameters of the longitudinal bore are those typical for surgical cannulated guides used in orthopedic procedures. Other dimensions of the cannulated guide 240 are those typical for surgical cannulated guides used in orthopedic procedures. Preferably, the cannulated guide 240 is constructed of stainless steel, although it is appreciated that any suitable surgical material may be used.
For illustration, and not for limitation, one embodiment of the cannulated guide 240 includes a diameter of the longitudinal bore 246 of about 0.095-0.099 inches. For illustration and not for limitation, one embodiment of the cannulated guide 240 has an overall length of about 3.2-3.4 inches and an outer diameter of about 0.25 inches tapering towards its distal end 244. As shown in the embodiment of
The cannulated guide 240 can be graduated with a series of calibrated markings 250 thereon. In the embodiment shown in
The cannulated guide 240 is removably attached to the free distal end 289 of the guide bracket arm 280 by the bracket connection means. The distal end 244 of the cannulated guide 240 is positioned towards the inner center of the bracket arch and aligned relative to the reference element 220 of the assembly 200. The attachment of the cannulated guide 240 to the guide bracket arm 280 is such that it will always allow the extended longitudinal axis of the longitudinal bore 246 to cross the radial center of the arched bracket. This extended longitudinal axis means the center line of the longitudinal bore 246 of the cannulated guide 240, whether directly within the length of the cannulated guide 240 or extending beyond its length.
One means of removably connecting the cannulated guide 240 to the guide bracket arm 280 is to have the guide fit through a bore 284 in the free end of the bracket and have a threaded guide screw 286 frictionally hold the cannulated guide 240 in place. Other attachment means are contemplated such as clips and other frictional attachment methods.
As discussed above, the shape and design of the assembly 200 provides an alignment means to ensure a proper relationship between the assembly elements, in particular a means to align the cannulated guide relative to the reference element. As shown in
When assembled, the assembly also defines a gap between the reference point and the distal end of the cannulated guide. This gap is typically, but not necessarily, a gap ranging through the typical lengths of a tibial bone tunnel for a ligament reconstruction procedure. For illustration and not for limitation, one embodiment of the assembly has a gap range of about 1 to 1.5 inches or preferably about 1.2 inches. This gap can be adjusted by adjusting the position of the cannulated guide in the guide bracket arm bore.
In the embodiment illustrated in
The embodiment shown in
Using the features of the guide assembly, guide systems can be implemented that further assist the surgeon during ligament reconstruction. Guide systems and assemblies can be configured to take advantage of defined anatomical placement sites for single or multi-bundle ligaments. The placement location of PCL ligaments on the femur (right) are shown as the dotted circle in
Using the example positionings shown in
In embodiments of the reference element of the guide assembly, a footprint target tip can be used which has guide recesses or apertures that help ensure the position of guide elements like a guide wire through the attachment site. For example, as shown in
Some embodiments are shaped to allow the guide assembly to locate tunnels from an outside-in position. The outside in position for locating the tunnels avoids the need to put the knee in hyper-flexion during surgery, helps protect the joint and minimizes condyle damage.
And
As illustrated, the footprint target tips can have an elongated tip portion 1024a and a curved neck portion 1024e to conform to the shape of the attachment location. This shaping provides a more steady reference point for the surgeon when the tip undersurface is placed on the attachment surface. The shaping also provides the opportunity to move the tip on the attachment surface until it can be referenced by or engaged with physical landmarks near the attachment location. For example, in
As shown in the examples of
To support single or double-bundle procedures, multiple cannulated guides can be used to guide the creation of the tunnels to receive the bundles. One example of a guide assembly for posterior entry is shown in
In some embodiments, rather than having the cannulated guides being generally perpendicular or parallel to the plane of the bracket adjustment, the cannulated guides may be aligned on the bracket with an offset reflecting the specific angles desired for tunnel placement for that specific procedures.
As shown in
It is contemplated that the footprint target tips can be removable tips that can be removed and replaced from a common guide system. The tips can be separate removable elements from the reference element or the reference element can be integrated with the target tip and the reference element can be removable to allow multiple shapes of footprint target tips to be used with the guide system. For example, separate tips can be made removable by having a removable connection such as a threaded end that mates with a threaded end of the rod of the reference elements. The tips can be organized in a kit to allow left, right, femur, tibia, ACL and PCL tips to be provided with the guide system. Given the different applications possible for the guide system, the length of the reference element, with or without the target tip, may be different for each application.
It is understood that although multiple cannulated guide assemblies can be used, embodiments that allow a single cannulated guide to move through different angles can also be used for multiple bundle procedures.
It is understood that the assemblies and systems disclosed can be modified so that they can be used in surgeries for either a left or a right knee. In one embodiment, there is both an assembly for use on a left knee and a different assembly for use on a right knee. In these left and right embodiments for use in knee surgeries, the assembly is modified to allow for the reference element insertion from a posterior position such as a posterior medial portal. In these left and right embodiments, footprint target tips can be used that are shaped specifically for use on a left or right knee.
Referring to one embodiment shown in
An example of a suitable guide assembly is described in U.S. Pat. No. 5,112,337, Feb. 5, 1991, entitled “VARIABLE ANGLE, SELECTIVE LENGTH TIBIAL DRILL GUIDE” to Lonnie E. Paulos et al. which is herein incorporated by reference in its entirety. For use with embodiments of the present invention, that guide assembly can be modified to have multiple cannulated guides and modified to have a footprint target tip as described above.
As shown in
If the embodiment similar to
As described earlier, embodiments can also enable tunnels to be created from an outside in position.
Using a guide assembly similar to the one of
Although the above example dimensions are listed with a degree of specificity, it is understood that the measurements are meant for illustration purposes and are not meant for limitation. Any dimension that allows the target tip to be inserted into the surgical location without damaging other tissues or interfering with other surgical devices would be suitable. Dimensions that allow for the target tip to engage landmarks on the surface of the tibia and femur are preferred.
The following description of one method of use of the ligament reconstruction assembly is to illustrate an embodiment of the methods of use for this assembly and is not intended as a limitation. It should be understood that while this invention is described in connection with particular examples and embodiments, the scope of the invention need not be so limited. Rather, those skilled in the art will appreciate that the following teachings can be used in a much wider variety of applications than the examples specifically mentioned.
One embodiment of the method is for use in arthroscopic posterior cruciate ligament (PCL) reconstruction surgery. In this embodiment, synthetic ligament grafts are provided or harvested and ligaments are reconstructed through well known methods such as those described in U.S. Pat. No. 5,300,077 filed Feb. 23, 1993 and U.S. Pat. No. 6,254,605 filed Nov. 27, 2000 to Howell both of which are herein incorporated by reference in their entirety. Specific to PCL reconstruction surgery, the location of tunnels and ligaments for the tibia and the femur are generally as described in U.S. Pat. No. 4,787,377 filed May 6, 1987 to Laboureau which is herein incorporated by reference in its entirety.
During this arthroscopic procedure, portals for the arthroscope and graft harvesting are made on the patient. Through these portals, the knee is examined by arthroscopic procedures and any observed minor defects or irregularities are taken care of.
As shown in
It is also possible to have the reference element and the target tip enter the patient's body from other posterior positions of the knee.
With the target tip of the reference element properly placed, the bracket can be adjusted by adjusting the rod bracket arm relative to the guide bracket arm to allow step 630 which is the positioning the distal end of the cannulated guide on the tibia so that the surgeon can pass a guide wire, drill or reamer through the guide.
Step 640 comprises drilling the transtibial PCL tunnel from the surgeons preferred position on the tibia to exit at the PCL anatomic insertion site as identified by the location of the target tip. With this assembly, during a PCL reconstruction operation, the surgeon can place the distal end of the cannulated guide, and therefore start the bone tunnel, from either an anterior medial or anterior lateral positions on the tibia, depending on the surgeon's preference. The means to keep the alignment of the bone tunnel with the target tip is provided by allowing the surgeon to adjust the shape of the assembly by adjusting the assembly bracket arms and securing them in the new shape with the bracket set screw. The assembly is able to enter from the posterior medial or lateral corners of the knee and can pass a guide pin or guide wire from any anterior position desired (from anterior lateral to anterior medial of the tibial tubercle) and at the same time pass the guide pin or guide wire at the correct inferior to superior angle so as to minimize neuro-vascular damage and reduce edge stress on the graft material. After placement of the entry point of the tunnel, the guide wire, drill or reamer is advanced through the cannulated guide towards the target tip. In one embodiment, the longitudinal axis of the cannulated guide is aligned with the target tip of the rigid rod. In one embodiment, a guide wire is passed by drilling or tapping through the cannulated guide to position the tunnel. If the target tip is placed at a designated exit point for a bone tunnel, the tunnel will be created and have an exit point at that point. In this mode, with the guide wire positioned in the tunnel, the cannulated guide can be removed, a collar can be placed over the guide wire and a cannulated bone boring means can be placed through the guide arm bore and over the collar and guide wire. With the bone boring means, such as but not limited to a coring drill bit, a drill bit or a reamer, aligned over the guide wire, the bone tunnel can be created with a proper alignment to the target tip.
With this posterior entry method, damage to the vascular clump and neurovascular structures of the knee are protected by the small size of the target tip and the surgeon's ability to visualize the exit point with the arthroscope. Because the assembly and guide pin can be passed under direct vision, it is a safe technique to help avoid damage to the neurovascular structures. It is also understood that positioning of the target tip could be done with x-ray equipment as currently used in the art.
Step 650 comprising positioning and drilling the femoral attachment site for the PCL which is visually placed and marked. The femoral lateral cortex is exposed and a bone boring means is utilized to create a small tunnel through the femur.
The surgeon can proceed to the replacement of the PCL of the knee using the medial anterior approach. Step 660 comprises passing the ligament graft through the tibia tunnel. One embodiment of this step is done by means of flexible pin connected to the leading end of the graft. When the flexible pin exits the tibia tunnel posterior, the end of the pins are grasped and pulled through tunnel and then used to position and secure the trailing end of the graft in the tibia tunnel which is step 670. Once positioned in the tibia tunnel, the leading end of the graft is then inserted into the femoral tunnel as step 680. The grafts can be positioned in the tunnel through the use of the flexible pin pulling the graft through the femoral tunnel. Once the leading end is positioned it is secured in the femoral tunnel as step 690.
This embodiment of the method is completed with step 695.
Although the procedures described above include a single tunnel in the tibia and the femur, it is contemplated that the assembly and the methods are just as suitable for a double bundle ligament graft. This would entail multiple tunnels being created in the tibia and the femur to accommodate the multiple graft bundles.
It is also contemplated that although the procedures above include detail using the ligament reconstruction guide assembly to create a tibia bone tunnel, is also understood that embodiments of the guide assembly described herein can be used to create bone tunnels in the femur and other bones from a posterior entry point.
Similar methods may be used to position target tips for locating the tunnel position on the femur for the PCL replacement procedure. In this method, the target tip is inserted posterior and the bottom surface of the footprint target tip is placed against landmarks on the roof surface of the femoral intercondylar notch. Alignment of the tunnels with the cannulated guide can be made by visually aligning the guide medial to the femur and drilling the tunnels utilizing an outside in procedure.
Similar methods may be used to position target tips for ACL replacement procedures from a posterior position. In this method, for placement of the tunnel position on the tibia, the target tip is inserted posterior and the bottom surface of the footprint target tip is placed against landmarks to nest with the tibial plateau of the intercondylar notch. The cannulated guide is positioned visually from an anterior position on the tibia. With the knee in a 90 degree flexed position, the femoral tunnels may be made by extending the tibial tunnels into the femur. Additionally, the placement of the tunnel positions on the femur, the target tip is inserted posterior and the bottom surface of the footprint target tip is placed against landmarks on the roof surface of the femoral intercondylar notch and the alignment of the tunnels can be made by visually aligning the bracket and cannulated guide lateral to the femur and drilling the tunnels utilizing an outside in procedure.
For guide system embodiments with multiple cannulated guides, similar procedures are utilized with guide embodiments such as those shown in
During an ACL reconstruction, for the tibia tunnels, the footprint target tips are inserted through the anterior medial or accessory medial portal and the scope is in the lateral portal. The bottom surface of the target tip is placed against landmarks to nest with the tibial plateau of the intercondylar notch. Then a tibial incision is made so that the cannulated guide can be pushed against the tibia. For methods using a single bundle, one guide pin is placed at an angle of about 60 degrees from the tibial crest. For methods using a double bundle, one guide pin is placed at about 50 degrees and the other is placed at about 70 degrees. The 50 degree pin is to guide placement of the tunnel for the AM bundle and the 70 degree pin is to guide placement of the tunnel for the PL bundle. Although specific angles are used as examples here, the angle can range at least 10 to 20 degrees on either side of the above angles with satisfactory results.
During an ACL reconstruction, the femur tunnels can be created with the knee at generally 90 degrees of flexion. With the tibia and femur in these positions, the femur tunnels are guided by inserting guide pins through the skin and entering the superior lateral femur from an outside-in position at the same angles to the tibia as described above. An alternative method of locating the femur tunnels is to run one of the femur guide pins from inside-out through a properly aligned tibial tunnel and place the distal hole of a guide assembly on that guide pin and drill the other guide pin from outside-in. For example, the anterior medial femur pin can be placed from inside-out through the anteromedial tibial tunnel and the posterolateral pin can be placed by putting one of the guide assemblies, with the proper angle offset, over the guide pin and use the other guide assembly to position the posterolateral pin from outside -in. Another embodiment is to run one guide pin through the tibial tunnel and use the footprint target tip on a guide assembly to position the other guide pin either from an inside-out or outside-in procedure. Yet another alternative is to use the guide assembly to directly position the femur ACL tunnels using the guide assembly and having an ACL femur specific footprint target tip. Using this embodiment with an outside-in procedure, the knee does not have to be put in hyper-flexion.
For locating the femur attachment sites in a PCL reconstruction procedure, the footprint target tip of the guide assembly can be inserted through the skin from an anterior position with a PCL femur specific footprint target tip. Using this embodiment with an outside-in procedure, the knee does not have to be put in hyper-flexion.
With respect to the above description then, it is to be realized that the optimum dimensional relationships for the parts of the invention, to include variations in size, materials, shape, form, function and manner of operation, assembly and use, are deemed readily apparent and obvious to one skilled in the art, and all equivalent relationships to those illustrated in the drawings and described in the specification are intended to be encompassed by the present invention.
Therefore, the foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation shown and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention. Although this invention has been described in the above forms with a certain degree of particularity, it is understood that the present disclosure has been made only by way of example and numerous changes in the details of construction and combination and arrangement of parts may be resorted to without departing from the spirit and scope of the invention.
This application is a continuation in part of co-pending U.S. patent application Ser. No. 12/937,402, filed Oct. 12, 2010 which is the National Stage of International Application PCT App. No. PCT/US09/34988, filed Feb. 24, 2009, which claims the benefit of U.S. Pat. App. No. 61/049,430, filed on Apr. 30, 2008; this application also claims benefit of U.S. Pat. App. No. 61/411,534, filed Nov. 9, 2010; and the entire contents of all the above applications are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61411534 | Nov 2010 | US | |
| 61049430 | Apr 2008 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 12937402 | Oct 2010 | US |
| Child | 13292062 | US |
