News Column

Patent Application Titled "Guide Tool for Cartilage Repair" Published Online

June 12, 2014



By a News Reporter-Staff News Editor at Politics & Government Week -- According to news reporting originating from Washington, D.C., by VerticalNews journalists, a patent application by the inventors Bake, Nina (Lidingo, SE); Wetterheim, Janarne (Bankeryd, SE); Axelsson, Robert (Granna, SE); Qvanstedt, Martin (Bankeryd, SE), filed on April 20, 2012, was made available online on May 29, 2014.

The assignee for this patent application is Episurf Ip Management Ab.

Reporters obtained the following quote from the background information supplied by the inventors: "General Background

"Pain and overuse disorders of the joints of the body is a common problem. For instance, one of the most important joints which are liable to wearing and disease is the knee. The knee provides support and mobility and is the largest and strongest joint in the body. Pain in the knee can be caused by for example injury, arthritis or infection. The weight-bearing and articulating surfaces of the knees, and of other joints, are covered with a layer of soft tissue that typically comprises a significant amount of hyaline cartilage. The friction between the cartilage and the surrounding parts of the joint is very low, which facilitates movement of the joints under high pressure. The cartilage is however prone to damage due to disease, injury or chronic wear. Moreover it does not readily heal after damages, as opposed to other connective tissue, and if healed the durable hyaline cartilage is often replaced by less durable fibro cartilage. This means that damages of the cartilage gradually become worse. Along with injury/disease comes a problem with pain, which results in handicap and loss of function. It is therefore important to have efficient means and methods for repairing damaged cartilage in knee joints.

"Today's knee prostheses are successful in relieving pain but there is a limit in the lifetime of the prostheses of 10-15 years. The surgical operation is demanding and the convalescence time is often around 6-12 months. In many cases today, surgery is avoided if training and painkillers can reduce the pain. Prostheses are therefore foremost for elderly patients in great pain, at the end of the disease process; a totally destroyed joint. There are different kinds of prostheses, such as half prosthesis, total prosthesis and revision knee, the latter used after a prosthesis failure. The materials used in today's knee prostheses are often a combination of a metal and a polymeric material, but other materials such as ceramics have also been used. The size of knee prostheses makes it necessary to insert them through open surgery.

"All treatments have shown only limited results, with implications such as high cost, risk of infection, risk of loosening, limited suitability for patients of different ages and the extent and location of damage.

"Specific Background

"Other attempts, except using prostheses, practiced at various clinics around the world with the main objective to repair or rebuild cartilage include biological approaches such as micro fractures, cartilage cell transplantation (ACI), periost flap, and mosaicplasty surgery.

"In the surgical operation of repairing cartilage tissue using transplants or implants it is critical that the cartilage repair object, for example an implant or a transplant, for example a healthy cartilage and bone plug is positioned in a precise manner. If the cartilage repair object is offset from its intended position it may cause increased wear or load on the joint. For example, if the cartilage repair object is tilted this may result in an edge that projects above the cartilage surface and causes wear on the opposing cartilage in the joint. Another example is when the cartilage repair object is placed in a position with the surface of the cartilage repair object projecting above the surface of the cartilage causing the joint to articulate in an uneven manner and increasing the load on an opposing point of the joint. For the patient, also small misplacements or deviations from an ideal position may result in pain, longer time for convalescence or even a surgical operation being done in vain and making it more difficult to repair the damage in the joint. Today there are known guide tools which may assist during placements of single implants or single transplants.

"Implantation of healthy cartilage and bone plugs into damaged cartilage areas is especially advantageous for young patients which still are growing and which has better abilities for self repair of cartilage compared to adults. Mosaicplasty involves moving round 'plugs' of cartilage and underlying bone to damaged areas. The plugs are each a few millimeters in diameter, and when multiple plugs are moved into a damaged area the result is a mosaic appearance. The multiple small plugs of cartilage look like mosaic tiles. Osteochondral autograft transfer (OATS) is a technique very similar to mosaicplasty but during OATS procedure the plugs are usually larger, and therefore only one or two plugs are needed to fill the area of cartilage damage. Because of this it does not take on the mosaic appearance, but the principle is the same.

"Today mosaicplasty or osteochondral autograft transfer (OATS) is performed using a graft harvesting tool, which harvests the osteochondral plug in a desired size. After the osteochondral plug is collected the plug is then placed in the recipient hole by using a plunger which is a part of the harvesting tool. These tools are not easy to use and a large burden is therefore placed on the surgeon in order not to misplace or misfit the implant.

"Supported grafts heal well, but unsupported grafts tend to subside and become covered by fibrous tissue. It is therefore important that the implanted plugs are correctly sized and the graft is seated in a well-supported recipient site.

"The guide tools on the market are lacking supportive design which gives a reliable, repeatable, cartilage repair with exact preciseness during placement of the implants. The implants on the market today is relying on the skills of the surgeon."

In addition to obtaining background information on this patent application, VerticalNews editors also obtained the inventors' summary information for this patent application: "The present invention provides a method for replacing a portion, e.g. diseased area and/or area slightly larger than the diseased area, of a joint, e.g. cartilage and/or bone, with a cartilage repair object and a guide tool which achieves a near anatomic fit of the cartilage repair object with the surrounding structures and tissues.

"A first aspect of the invention is a guide tool for cartilage repair at an articulating surface of a joint used to guide harvesting and also insertion of a healthy cartilage and bone plug from a non bearing part of a joint to an area replacing the cartilage of a cartilage injury site. The guide tool according to the invention may also be used to guide insertion of implants. The actual harvesting may be performed using a cartilage harvesting tool inside the guide tool according to the invention. The individually designed guide tool according to the invention may be designed to harvest plugs or designed for placement of plugs into the damage site or designed to be able to guide both harvesting and placement of plugs or implants. The cartilage harvesting tool used inside the guide tool may also be equipped with a plunger used for the placement of the harvested cartilage and bone plug into the damaged cartilage area.

"The guide tool is equipped with a positioning body and a guide body with at least one guide channel which goes through said positioning body and said guide body. The positioning body has a cartilage contact surface that is designed to fit the contour of the cartilage or subchondral bone in the joint in a predetermined area surrounding the site of diseased cartilage. The positioning body has a guide channel which has at least one cross-sectional profile that is designed to correspond to an insert tool. The guide channel has at least one muzzle facing the cartilage surface at a position corresponding to the site of the diseased cartilage.

"The insert tools are used inside the guide channel of the guide tool. The insert tools may fit in the guide channel, with a slight tolerance to allow a sliding movement of the cartilage harvesting and the insert tool into the guide channel. The insert tools are in different embodiments of the invention provided e.g. as a cartilage harvesting and insert tool or as a drill bit.

"A guide tool according to the invention is equipped with a positioning body comprising a guide body comprising at least one or more guide channels and a cartilage contact surface and wherein the cartilage contact surface is designed to fit the individual contour of the cartilage or subchondral bone in the joint in a predetermined area surrounding a site of diseased cartilage and said guide channels have a cross-sectional profile that is designed to correspond to a cross-section of the insert tools and each guide channel has a muzzle facing a cartilage damage at a position facing the site of the diseased cartilage, characterized in that the guide channels are placed or designed for placement within the guide body in a predetermined pattern, wherein the position and relative distance and angle of said guide channels are designed to fit an individual cartilage damage site.

"In another embodiment the guide tool 1 according to the invention has at least one of said guide channels 200 having an outer portion 234 and an inner portion 232 and that said outer portion 234 is larger in volume than said inner portion 232 and between the outer portion 234 and the inner portion 232 is a stop function 214 or the cross-sectional diameter 212 of the outer portion 234 is smaller than the cross-sectional diameter 262 of the inner portion 232 or for example the cross-sectional diameter 212 of the outer portion 234 is less than 30% smaller or 1-20% smaller compared to cross-sectional diameter 262 of the inner portion 232.

"In another embodiment a guide tool 1 according to the invention has a cartilage contact surface (208) of the positioning body 206 of the guide tool 1 having three contacting points, spread out around the guide body 206, for contacting parts of the joint in order to provide stable positioning of the guide tool 1 in the joint.

"In another embodiment a guide tools according to the invention has a cartilage contact surface 208 located on the positioning body 206 of the guide tool 1 and the cartilage contact surface 208 has three contacting points, spread out around the guide body 206, for contacting parts of the joint in order to provide stable positioning of the guide tool 1 in the joint. For example the cartilage contact surface may be 10-90% larger than the area of the muzzle or the cartilage contact area may be perforated in 10-90 area % by muzzle openings.

"The guide tool (1) according to the invention comprises a guide channel (200) and a positioning body (206) which further comprises a cartilage contact surface (208). The positioning body (206) extends laterally outside the periphery of the guide channel (200)

"In another embodiment a guide tool 1 according to the invention, has a guide channel 200 having a height 218 of 0.3-20 cm or preferably 3-10 cm.

"In another embodiment the repair system according to the invention, includes cartilage repair objects which are implants or a healthy cartilage and bone plugs.

"In another embodiment a guide tool 1 according to the invention has a relative shortest distances 804 between the guide channels of 1-3 mm.

"In another embodiment a guide tool 1 according to the invention comprises guide channels with a relative shortest distances 804 between the guide channels of 1-3 mm.

"In another embodiment, the method of designing a guide tool 1 for cartilage repair in an articulating surface of a joint according to the invention, comprises the steps of: I. determining physical parameters for cartilage damage in a joint and generating design parameters for cartilage repair objects 600 and their relative placement in a predetermined pattern, comprising: a. selecting repair objects to fit the individual cartilage damage site wherein the repair objects have; cross sectional areas adapted to fit the surface area of the cartilage damage site lengths adapted to fit the selected joint and/or type of cartilage damage surfaces intended to align with the articular cartilage surface in the joint, based on the healthy surface contour curvature b. determining, based on the obtained image data, positions and angles of the selected cartilage repair objects, wherein the positions and angles are adapted so that the selected repair objects fit the individual cartilage damage site II. generating design parameters of the guide tools, for placement of the cartilage repair objects comprising the following steps; a) generating the design for an upper part 234 and a lower part 232 of a guide channel 200 in a guide body 206 extending from the positioning body 202, said guide channel 200 passing through said positioning body 202 and said guide body 206 wherein the angles and positions are generated dependent on and substantially corresponding to the determined angles and positions of the selected cartilage repair objects, and wherein; the design for the lower part 232 of all the guide channel 200 is generated dependent on and substantially corresponding to the determined cross sectional areas, of the selected cartilage repair objects.

"In another embodiment, the method of designing a guide tool 1 for cartilage repair in an articulating surface of a joint according to the invention, comprises the steps of: determining physical parameters for a cartilage damage in a joint and generating design parameters for a number of cartilage repair objects 600, size of cartilage repair objects 600 and their relative placement in relation to the other cartilage repair objects in a predetermined pattern depending on the cartilage damage, comprising: 2. selecting cartilage repair objects 600 to fit the individual cartilage damage site in a joint wherein said repair objects have; cross sectional areas adapted to fit the surface area of the cartilage damage site, in combination with other cross section areas of other repair objects or alone lengths adapted to fit the selected joint and/or type of cartilage damage surfaces intended to align with the articular cartilage surface in the joint, based on the healthy surface contour curvature 3. determining, based on the obtained image data received from X-ray, CT, MRI or other imaging techniques scanning the cartilage damage in a patient, positions and angles of the selected cartilage repair objects, wherein the positions and angles are adapted so that the selected repair objects fit said individual cartilage damage site 4. generating design parameters of the guide tool 1, designed for placement of the cartilage repair objects comprising the following steps; a) generating the design for an upper part 234 and a lower part 232 of a guide channel 200 in a guide body 206 extending from the positioning body 202, said guide channel 200 passing through said positioning body 202 and said guide body 206 wherein the angles and positions are generated dependent on and substantially corresponding to the determined angles and positions of the selected cartilage repair objects, and their intended or designed placement in a joint wherein; the design for the lower part 232 of all the guide channel 200 is generated dependent on and substantially corresponding to the determined cross sectional areas, of the selected cartilage repair objects. b)

"In another embodiment the method of designing a guide tool (i) for cartilage repair in an articulating surface of a joint according to the invention comprises the steps of: I. determining physical parameters for cartilage damage in a joint and generating design parameters for cartilage repair objects (600) and their relative placement in a predetermined pattern, comprising: a) obtaining image data representing a three dimensional image of a bone member of the joint; b) identifying in the obtained image data and individual cartilage damage in an articulate surface of the bone member; c) determining based on the obtained image data the location of the individual cartilage damage; d) determining based on the obtained image data the size and shape of the individual cartilage damage; e) determining a cartilage damage site based on the determined size and shape of the cartilage damage; f) determining based on the obtained image data the surface contour curvature of the individual cartilage damage site 92 and/or the subchondral bone in the joint in the predetermined area comprising the individual cartilage damage site; g) determining a representation of a healthy surface contour curvature comprising the individual cartilage damage site h) selecting repair objects to fit the individual cartilage damage site wherein the repair objects have; cross sectional areas adapted to fit the surface area of the cartilage damage site lengths adapted to fit the selected joint and/or type of cartilage damage surfaces intended to align with the articular cartilage surface in the joint, based on the healthy surface contour curvature i) determining, based on the obtained image data, positions and angles of the selected cartilage repair objects, wherein the positions and angles are adapted so that the selected repair objects fit the individual cartilage damage site II. generating design parameters of the guide tool 1, for placement of the cartilage repair objects comprising the following steps; a. generating the contact points for a cartilage contact surface 208 of a positioning body 202 dependent on said determined surface contour curvature of the cartilage and/or the subchondral bone in the joint in a predetermined area comprising and surrounding the site of cartilage damage, such that said cartilage contact surface 208 of the positioning body 202 fits to said surface contour of the cartilage or the subchondral bone in the joint. b. generating the design for an upper part 234 and a lower part 232 of a guide channel 200 in a guide body 206 extending from the positioning body 202, said guide channel 200 passing through said positioning body 202 and said guide body 206 wherein the angles and positions are generated dependent on and substantially corresponding to the determined angles and positions of the selected cartilage repair objects, and wherein; the design for the lower part 232 of all the guide channel 200 is generated dependent on and substantially corresponding to the determined cross sectional areas, of the selected cartilage repair objects 600 c. Optionally generation of suggestions of where and how the healthy cartilage and bone plug are to be harvested in a manner so that the contour curvature for the articulate surface of the bone plug corresponds to the curvature that covers the cartilage damage wherein the cartilage and bone plug are to be placed.

"In another embodiment the method of designing a guide tool 1 for cartilage repair in an articulating surface of a joint according to the invention, includes generating design parameters for the guide channel 200 to have a height 218 of 0.3-20 cm for example of 3-10 cm.

"In another embodiment the method of designing a guide tool 1 for cartilage repair in an articulating surface of a joint according to the invention includes a cartilage repair object which is an implant or a healthy cartilage and bone plug.

"In another embodiment the method of designing a guide tool 1 for cartilage repair in an articulating surface of a joint according to the invention includes image data representing an image of the joint is obtained using magnetic resonance imaging (MRI), computerized tomography (CT) imaging or a combination of both, or other suitable techniques such as delayed Gadolinium-enhanced MRI of cartilage (dGEMRIC) techniques.

"In another embodiment the guide tool is designed to replace a small cartilage damage only replacing a part of the cartilage in a joint. For example using cartilage repair objects with crossectional profiles of between 0.1 cm.sup.2 and 5 cm.sup.2, between 0.5 cm.sup.2 and 3 cm.sup.2, or preferably between about 0.5 cm.sup.2 and 2 cm.sup.2 intended to repair cartilage damages of areas between 0.1-10 cm.sup.2.

"In another embodiment the guide tool is designed to comprise at least one muzzle which in total has an area of 10-90% of the total cartilage surface area spread of the guide tool.

"In another embodiment the guide tool is designed to comprise a design for the lower part 232 of all the guide channel 200 generated dependent on and substantially corresponding to the determined cross sectional areas, of the selected cartilage repair objects boo in order to make the guide tool suitable to guide the insertion of the cartilage repair objects into the cartilage repair site.

"In another embodiment according to the invention the guide tool is designed to be suitable for preparing the cartilage damage site before placing of implants or plugs and also for guiding the placing cartilage repair objects into the cartilage repair site of a joint.

"In another embodiment according to the invention the guide tool is designed to insert plugs or implants which has a diameter of between 0.1 cm.sup.2 and 5 cm.sup.2, between 0.5 cm.sup.2 and 3 cm.sup.2, or preferably between about 0.5 cm.sup.2 and 2 cm.sup.2.

"In another embodiment according to the invention the guide tool is designed to have a muzzle with a cross sectional diameter which is determined depending on the size and shape of the crossectional diameter of the implants or bone plugs so that the muzzle of the guide tool corresponding to the crossectional diameter of the implants or bone plugs in a way that the implants or bone plugs allows to be inserted through the muzzle. For example the cross-sectional area of the muzzle is designed to differ in +/-0-5% compared to the crossectional area of the implants or plugs.

"Further a method using the guide tool 1 according to the invention comprises the steps; a) using the data and the guide tool designed according to the design method described in claims 6-9 b) inserting the individually shaped guide tool from step a) on the cartilage damage site 806 and optionally fastening the guide tool to the cartilage. c) using selected guide channels 200 in the guide tool 1 for guidance when drilling out recesses in the bone and cartilage within the cartilage damage site of the patient. d) placing selected cartilage repair objects 600 into recesses created in step c) using the guide tool 1 for guidance.

BRIEF DESCRIPTION OF THE FIGURES

"The present invention will be further explained below with reference to the accompanying drawings, in which:

"FIG. 1 shows an exemplifying embodiment of a knee joint with a cartilage repair site repaired using the cartilage repair system according to the invention and a guide tool.

"FIG. 2 shows an exemplifying embodiment of a guide tool according to the present invention placed in a knee joint.

"FIG. 3 shows an exemplifying embodiment of different insert tools which may be used inside the guide channels of the guide tool; cartilage harvesting and insert tool and a drill tool according to the present invention.

"FIG. 4 shows a schematic overview of an exemplifying embodiment of a design method in accordance with the invention used for designing a patient specific guide tool.

"FIG. 5 shows an exemplifying embodiment of a sectional view of a guide tool according to the present invention.

"FIG. 6a-c show exemplifying embodiments of cartilage repair object and a control lock tools used during mosaic implantation according to the invention.

"FIG. 7A-H show an exemplifying embodiment of a surgical method using the guide tool according to the invention.

"FIG. 8A-G show an exemplifying embodiment continuation of a surgical method using the guide tool according to the invention.

"FIG. 9A-B show an exemplifying embodiment of cartilage damage in the tibia bone. The figure represents a sample image, in a side view, from a set of several images which together represent a three dimensional image of a joint.

"FIG. 10 shows schematically in an exemplifying embodiment of the invention how image based tools of the invention may be used to visualize in an image a model of a recess in the cartilage and the subchondral bone for an implant.

"FIG. 11 shows schematically in an exemplifying embodiment of the invention how image based tools of the invention may be used to visualize in an image a model of an inserted cartilage repair object according to the generated design parameters.

"FIG. 12A-B show examples of a front view of the articular cartilage parts of the femur bone.

"FIG. 13 shows an exemplifying embodiment of the invention, wherein the guide tool covers both the harvesting cartilage area and the cartilage area of the cartilage damage.

"FIG. 14 shows an exemplifying embodiment of the invention, wherein the guide tool comprises one guide channel

"FIG. 15 shows an exemplifying embodiment of the invention, wherein the guide tool comprises guide channels having a lower and an upper part with the same diameter."

For more information, see this patent application: Bake, Nina; Wetterheim, Janarne; Axelsson, Robert; Qvanstedt, Martin. Guide Tool for Cartilage Repair. Filed April 20, 2012 and posted May 29, 2014. Patent URL: http://appft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=1281&p=26&f=G&l=50&d=PG01&S1=20140522.PD.&OS=PD/20140522&RS=PD/20140522

Keywords for this news article include: Surgery, Autograft, Prosthetics, Bone Research, Medical Devices, Episurf Ip Management Ab.

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