Patent Application
20240374394
The present invention relates generally to a medical device for implantation in a human patient.
Knee replacement surgery is one of the most commons surgical procedures to date performed at more than a million patients every year worldwide. The most common reason for performing a knee replacement surgery is that the patient suffers from knee joint osteoarthritis, which is a syndrome in which a low-grade inflammation results in pain in the joints. The low-grade inflammation is caused by abnormal wearing of the cartilage that covers and acts as a cushion inside joints, which results in a decrease of the synovial fluid that lubricates the knee joint.
In conventional surgery the surgeon places a prosthesis on the lateral condyle, the medial condyle or both the medial and the lateral condyle. The prosthesis could further more comprise a contacting surface placed on the top part of the tibia bone and an artificial part replacing the knee cap.
The procedure usually takes up to two hours and the surgeon will make a single cut (10 to 30 cm long) down the front of the knee. The kneecap is moved to one side to reach the knee joint. The worn or damaged surfaces are removed and the bone are shaped to fit the artificial knee joint.
The average patient age is between 65 and 75. Of these surgeries, approximately 80% are unilateral (only one knee replaced) and 20% are bilateral.
The knee joint comprises proximal contacting surfaces, being sections of the medial condyle, the lateral condyle and an area of the femoral bone between the medial and the lateral condyle and a distal contacting surface being a cross-section of the proximal part of the tibia bone. Furthermore the knee joint comprises the patella which is a, triangular bone which articulates with the femur and covers and protects the knee joint. The knee joint also comprises the minisci which are cartilaginous elements within the knee joint which serve to protect the ends of the bones from rubbing on each other. The minisci also acts as shock absorbers in the knee. There are two menisci in each knee, the medial meniscus and the lateral meniscus.
Osteoarthritis is a common condition of cartilage failure that can lead to limited range of motion, bone damage and invariably, pain. Due to a combination of acute stress and chronic fatigue, osteoarthritis directly manifests itself in a wearing away of the articulating surface and, in extreme cases, bone can be exposed in the joint. Some additional examples of cartilage failure mechanisms include cellular matrix linkage rupture, chondrocyte protein synthesis inhibition, and chondrocyte apoptosis.
A medical device for implantation in a knee joint of a human patient is provided. The medical device comprises at least two parts adapted to be connected to each other after implantation in the knee joint of the patient to form an assembled medical device. The assembled medical device has an outer surface, being curved, creating a curved outer surface along a frontal to dorsal curved length axis following the curved outer surface, having a middle section, when said medical device is implanted in a functional position in the knee joint. The middle section is placed in the middle of the curved outer surface along the length axis. The medical device further comprising; an inner surface comprising a first point, a second point, a third point, a fourth point. The inner surface or an imaginary special extension of said inner surface comprising a fifth point, and a sixth point. The imaginary special extension fills out a circumferential discontinuity transverse to the length axis extension, wherein said curved inner surface along the frontal to dorsal curved length axis is hollow and has an opening. An imaginary circle is immersed within the opening, with maximum size, wherein any discontinuity in the circumferential extension of the end portions of the artificial femur surface, closest to the opening, along the circumferential extension of the circle, is filled out by said circle, wherein said inners surface or said imaginary circular wall created by the circle immersed within the hole, comprising the position for the fifth and sixth point. All points are located on different places along an inner length axis of said inner surface, or an imaginary special extension thereof. The inner length axis is adapted to be a length axis distributed in a defined relation to the outer length axis. The first straight line, reaching from the first point to the second point is parallel to a second straight line reaching from the third point to the fourth point, which in turn is parallel to a third straight line reaching from the fifth point to the sixth point. The first straight line is placed closer to the middle section of the curved outer surface, than the second and third straight lines. The second straight line is longer or of equal length than the first straight line and placed between the first and third straight lines. The second straight line is longer than the third straight line when the medical device is placed in the functional position in the knee joint, and the assembled medical device is rigid and adapted to clasp the distal portion of the femoral bone such that the assembled medical device cannot be removed when assembled and placed on the distal portion of the femoral bone.
According to one embodiment, the medical device could be adapted to be placed on an intact distal portion of the femoral bone.
The knee joint includes a contacting surface of the distal portion of the femoral bone or femur, and a tibia surface, including a contacting surface of the proximal portion of the tibia bone or tibia. The contacting surfaces at least partly contacting each other in a functional knee joint, carrying weight in the knee joint, the femur also contacts the patella in the patella femur contacting surface contacting the patella contacting surface. The femoral bone has an elongated distribution leading distally to a medial and lateral condyle of the femur, wherein a center axis of the elongated distribution of the femoral bone being the elongated femur center axis, wherein the condyles are integrated in the femur in an upside-down Y-configuration having one medial and one lateral condyle with a rounded form, towards a ball shaped condyle, integrated in the upside down Y-shaped double neck of the femur. The condyle has an equatorial plane dividing the condyle in half of an imaginary complete ball shaped configuration, when imagining the condyle having a complete towards a ball shape configuration also through the neck of the femur. The condyles has a center axis substantially in the centre of both the medial and lateral condyle, perpendicular to the elongated femur centre axis, defined as the femur condyles center axis, placed dorsally to the elongated femur center axis. The condyles has a part of the circumference being the femur contacting surface, extending in frontal-dorsal direction following the movement of the knee, less than 180 degrees. The equatorial plane has a center axis extending perpendicularly from the center thereof, defining the condyle equatorial plane center axis. The hollow medical device comprises a central part and a surrounding part, the central part has a center axis in the center thereof, being aligned with the condyle equatorial plane center axis, wherein the surrounding part surrounding the surface of the femur condyle or a partly modified femur condyle surface not including the central part. The artificial knee joint surface, comprising an artificial femur surface adapted to at least partly replace and replacing at least one of; the femur contacting surface of the medial condyle and the femur contacting surface of the lateral femoral condyle and the patella femur contacting surface, and adapted to be placed to contact, at least one of and at least a part of, the tibia contacting surface or an artificial replacement therefore and the patella contacting surface or an artificial replacement therefore, when mounted in the knee joint. The artificial femur surface is hollow and distally has at least to a part an outer surface being curved, the artificial femur surface comprising; at least one first beyond part extending from the surrounding part of the artificial femur surface beyond the equatorial plane of the equatorial half of the condyle, extending away from the contacting surface, on at least one of the medial and lateral condyle, on at least a part of the artificial femur surface. The at least one beyond part is extending at least to a part on both a circumferential quarter of the equatorial plane placed; a) most dorsal and b) most frontal of the artificial femur surface, when the artificial femur surface is mounted on the femur in its functional position in the knee joint. On the inner surface of the hollow artificial femur surface, the at least one first beyond part is adapted to have, a closest distance to the condyle equatorial plane center axis, being smaller than the largest distance from the inner surface of the artificial femur surface to the condyle equatorial plane center axis, the closest and longest distance are extending from both of the two circumferential quarters of the equatorial plane placed; a) most dorsal and b) most frontal of the artificial femur surface, thus adapted to create and creating a more stable position of said artificial femur surface, when mounted on said at least one of the femoral condyles in the functional position in the knee joint.
The knee joint includes a contacting surface of the distal portion of the femoral bone or femur, and a tibia surface, including a contacting surface of the proximal portion of the tibia bone or tibia. The contacting surfaces at least partly contacting each other in a functional knee joint, carrying weight in the knee joint, the femur also contacts the patella in the patella femur contacting surface contacting the patella contacting surface. The femoral bone has an elongated distribution leading distally to a medial and lateral condyle of the femur a center axis of the elongated distribution of the femoral bone is the elongated femur center axis, the condyles are integrated in the femur in an upside-down Y-configuration having one medial and one lateral condyle with a rounded form, towards a ball shaped condyle, integrated in the upside down Y-shaped double neck of the femur. The condyle has an equatorial plane dividing the condyle in half of an imaginary complete ball shaped configuration, when imagining the condyle having a complete towards a ball shape configuration also through the neck of the femur. The condyles has a center axis substantially in the centre of both the medial and lateral condyle, perpendicular to the elongated femur centre axis, defined as the femur condyles center axis, placed dorsally to the elongated femur center axis. The condyles has a part of the circumference being the femur contacting surface, extending in frontal-dorsal direction following the movement of the knee, less than 180 degrees. A line from the femur contacting surface's most proximal-dorsal point in the periphery of the condyle, substantially in the middle of the contacting surface in medial-lateral direction, is extending perpendicular through the femur condyle center axis until it reaches the periphery of the frontal-distal part of the condyle. Such line extended to a plane, horizontally in medial-lateral direction, defines a special equatorial plane, including the complete femur contacting surface in the equatorial divided half of an imaginary complete ball shaped configuration of the condyle. The special equatorial plane has a center axis extending perpendicularly from the center thereof, defining the condyle special equatorial plane center axis. The medical device, comprises a central part and a surrounding part, the central part is aligned with a medical device center axis and the surrounding part surrounding the surface of the femur condyle or a partly modified femur condyle surface not including the central part. The artificial knee joint surface, comprises an artificial femur surface adapted to at least partly replace and replacing at least one of; the femur contacting surface of the medial condyle and the femur contacting surface of the lateral femoral condyle and the patella femur contacting surface, and adapted to be placed to contact, at least one of and at least a part of, the tibia contacting surface or an artificial replacement therefore and the patella contacting surface or an artificial replacement therefore, when mounted in the knee joint. The artificial femur surface is hollow and distally has at least to a part an outer surface being curved. The artificial femur surface comprising at least one first beyond part extending from the surrounding part of the artificial femur surface beyond the special equatorial plane of the equatorial half of the condyle including the complete contacting surface, extending away from the contacting surface, on at least one of the medial and lateral condyle, on at least a part of the artificial femur surface. The at least one beyond part is extending at least to a part on both a circumferential quarter of the equatorial plane placed; a) most dorsal and b) most frontal of the artificial femur surface, when said artificial femur surface is mounted on the femur in its functional position in the knee joint. On the inner surface of the hollow artificial femur surface, the at least one first beyond part is adapted to have, a closest distance to the condyle special equatorial plane center axis, being smaller than the largest distance from the inner surface of the artificial femur surface to the condyle special equatorial plane center axis, the closest and longest distance are extending from both of the two circumferential quarters of the equatorial plane placed; a) most dorsal and b) most frontal of the artificial femur surface, thus adapted to create and creating a more stable position of said artificial femur surface, when mounted on said at least one of the femoral condyles in the functional position in the knee joint.
The knee joint comprises a femur surface, being a contacting surface of the distal portion of the femoral bone or femur, and a tibia surface, being a contacting surface of the proximal portion of the tibia bone or tibia. The contacting surfaces are at least partly contacting each other in a functional knee joint. The femoral bone have an elongated distribution leading distally to a left and right condyle of the femur, the condyles having a cross-section parallel to the elongated distribution with a substantially round shaped configuration distally on the condyles, when viewed from the lateral or medial side of said femoral bone. The section have a maximum diameter, substantially perpendicular to the elongated distribution of the femoral bone, wherein the medical device comprises an artificial knee joint surface comprising; an artificial femur surface adapted to at least partly replace and replacing the joint surface of at least one of the femoral condyles, placed distally on said femoral bone and adapted to be placed to contact, at least partly, with said tibia contacting surface, or an artificial replacement therefore, when mounted in the joint. The artificial femur surface, comprising at least one first beyond part adapted to cover and/or go into the bone of the femur on at least a part of the femur beyond the maximum diameter of the condyle in the proximal direction of the elongated distribution of the femur, when mounted on the femur in its functional position in the joint. The at least one first beyond part is adapted to have a closest distance to a centre axis of the elongated distribution of the femur, being smaller than the closest distance of a point of said maximum diameter of the femoral condyle and the centre axis of the elongated distribution of the femur. Thereby the medical device is adapted to create and creating a more stable position of the artificial femur surface, when mounted on at least one of the femoral condyles in the functional position.
According to one embodiment the medical device comprises an artificial knee joint surface comprising; an artificial tibia surface adapted to at least partly replace and replacing the tibia contacting surface, placed proximally on the tibia and adapted to at least partly contact said femur contacting surface or an artificial replacement therefore, when mounted in the joint. The artificial tibia surface, comprising at least one first beyond part adapted to cover and/or going into the bone of the femoral bone or an artificial replacement therefore, on at least a part of the femoral bone beyond the maximum diameter of the condyle in the proximal direction of the elongated distribution of the femoral bone, when mounted on said femoral bone or an artificial replacement therefore in its functional position in the joint. The at least one first beyond part is adapted to have a closest distance to a centre axis of the elongated distribution of the femoral bone, being smaller than the closest distance between a point of said maximum diameter of said femoral bone and the centre axis of the elongated distribution of the femoral bone, thus adapted to create and creating a more stable position of the artificial tibia surface, when mounted on at least one of the femoral condyles, or artificial replacements therefore, in the functional position.
According to one embodiment, the medical device has a substantially horseshoe-shaped section having a base, two ends, an inner surface and an outer surface. A first straight line reaches from a first end of said inner surface of said horseshoe-shaped section to a second end of said horseshoe-shaped section; the first straight line is positioned in an insertion opening of said medical device. A second straight line, reaches between two points on said inner surface of said horseshoe-shaped section. The first straight line and the second straight line are parallel, the first straight line is shorter than the second straight line, and the second straight line is placed closer to the base of the horseshoe-shaped section than the first straight line.
According to one embodiment the medical device is adapted to be fixated to the medial condyle of a human patient, which could be done through the medical device being adapted to clasp said medial condyle. However it is equally conceivable that the medical device is adapted to be fixated to the lateral condyle of a human patient, which could be done through the medical device being adapted to clasp said lateral condyle.
According to another embodiment the medical device is adapted to be fixated to both the medial condyle and the lateral condyle of the human patient, which could be done through the medical device being adapted to clasp both said medial condyle and said lateral condyle.
According to one embodiment the medical device comprises at least two parts adapted to be connected to each other after implantation in the knee joint.
According to one embodiment the medical device further have a largest cross sectional distance and at least one movable member for varying said largest cross sectional distance of the medical device. The moveable member could comprise at least one elastic member, which could be at least one part of the medical device adapted to enable mounting of the medical device on at least one of the lateral condyle and the medial condyle of the human patient.
The medical device according to any of the embodiments herein could be adapted to have a variable closest distance between said beyond part and said center axis allowing mounting of said artificial femur surface onto at least one of the femur condyles having a first larger closest distance, having a second smaller closest distance when implanted in the functional position in the knee joint.
According to one embodiment the medical device is adapted to have an opening with a variable size, larger during mounting and smaller, when implanted in the functional position in the knee joint.
The knee joint comprises a first contacting surface, being a surface of the distal portion of the femoral bone, and a second contacting surface, being a surface of the proximal portion of the tibia bone. According to one embodiment the medical device is adapted to be in connection with the first contacting surface when implanted in the knee joint. The connection could be a direct connection with the first contacting surface, or an indirect connection with the first contacting surface. In the embodiments where the connection is an indirect connection a material could be positioned between the medical device and the first contacting surface. The material could be a material selected from a group consisting of: adhesive materials, elastic materials and bone cement.
The knee joint comprises a first contacting surface, being a surface of the distal portion of the femoral bone, and a second contacting surface, being a surface of the proximal portion of the tibia bone. According to one embodiment the medical device comprises three parts wherein at least two parts are adapted to be mechanically connected to each other when implanted in the knee joint, the at least two parts are fixated to the first contacting surface. A third part is fixated to the second contacting surface. The at least two parts fixated to the first contacting surface are in moveable connection with the third part fixated to the second contacting surface, when the medical device is implanted in the knee joint. The movable connection could be a movable direct connection or a movable indirect connection.
According to one embodiment a material is positioned between at least two parts fixated to said first contacting surface and said third part fixated to said second contacting surface. The material could be a material adapted to reduce friction in the knee joint. Such as a lubricating fluid, which preferably is a biocompatible lubricating fluid such as hyaluronic acid. According to another embodiment the material adapted to reduce friction is a fluorpolymer material, such as PTFE.
According to one embodiment the medical device is adapted to be fixated to a bone of the human patient using a fixation element selected from a group consisting of: at least one screw, at least one pin, at least one portion of at least one of the parts adapted to be introduced into the other part, the parts being adapted to be sliding into the other part, form fitting, welding, adhesive, pin, wire, a ball mounted into a cup being portions of said parts, a male portion of one part mounted into a female portion of the other part, a key introduced into a lock being portions of said parts, band, or other mechanical connecting members.
According to one embodiment the medical device is adapted to be fixated to the distal part of the femoral bone using a through-going fixation element, which could be a through-going fixation element adapted to travel from the frontal part of the medical device, positioned at the frontal part of the femoral bone, through the femoral bone and into the rear part of the medical device, positioned on the rear part of the femoral bone. The through-going fixation element could be a through-going fixation element selected from a group consisting of: screws, pins, wire, rivets, band and cord. The through-going fixation element could further be assisted by an adhesive.
The at least two parts adapted to be connected to each other after implantation in said knee joint, according to any of the embodiments, could be connected to each other using at least on element selected from a group consisting of: at least one screw, at least one pin, at least one portion of at least one of the parts adapted to be introduced into the other part, the parts being adapted to be sliding into the other part, form fitting, welding, adhesive, wire, a ball mounted into a cup being portions of said parts, a male portion of one part mounted into a female portion of the other part, a key introduced into a lock being portions of said parts, band, or other mechanical connecting members.
According to one embodiment the medical device is adapted to be fixated to the distal part of the femoral bone without penetration of the cortex of said femoral bone.
The distal part of the femoral bone has a largest cross sectional distance. According to one embodiment the medical device comprises an opening smaller than the largest cross sectional distance when the medical device is mounted on the distal part of the femoral bone in a functional position. The opening could be larger than the largest cross sectional distance when the medical device travels over the distal part of the femoral bone.
The medical device according to any of the embodiments could be made of a single material, or at least a part adapted to clasp the medial and/or the lateral condyle or the proximal part of the tibia bone, could be made from the same material.
The elastic member, according to any of the embodiments above, could comprise an elastic material, which could be elastic polymer material or an elastic metal material. In embodiments where the elastic material is an elastic polymer material the elastic polymer material could be an elastic polymer material selected from a group consisting of: polystyrene, poly (ethylene-butylene), polyurethane elastomeric material, polyamide elastomeric materials, polyester elastomeric materials, elastic copolymers of ethylene, vinyl acetates, unsaturated aliphatic monocarboxylic acids and monocarboxylic acids.
In embodiment where the elastic material is an elastic metal material, the elastic material could be a biocompatible metal material, such as titanium or tantalum. It is also conceivable that the material is a multi-layered material in which at least one layer is adapted to protect against the body cells. According to one embodiment at least one layer is a Parylene layer.
The medical device according to any of the embodiments herein could have a variable closest distance being variable due to a movable beyond part, the beyond part could comprise a slit for being movable. According to another embodiment the beyond part is bendable.
The movable beyond part could comprise a locking position to lock the beyond part in its position, when implanted in the functional position in the hip joint.
The medical device could comprising a locking member for locking the movable beyond part in a locking position, when implanted in the functional position in the hip joint. The locking member could comprising at least one of a locking wire and a locking ring.
According to one embodiment the size of the opening is adapted to be fixed in a locking position, when implanted in the functional position in the hip joint.
The medical device according to anyone of the embodiments could comprise a locking wire to lock the opening to be fixed in a locking position, when implanted in the functional position in the knee joint.
The medical device according to any of the embodiments could comprise a locking ring for locking the opening to be fixed in a locking position, when implanted in the functional position in the knee joint.
The locking wire could be adapted to pass through the femur condyle, when implanted in the functional position in the knee joint, or the locking ring could be adapted to be mounted onto the femur condyle, when implanted in the functional position in the knee joint.
According to another embodiment the medical device comprises an artificial tibia surface comprising at least on of a medial and lateral tibia surface, adapted to contact at least one of the femur condyles or an artificial replacement therefore.
According to yet another embodiment the medical device could comprise an artificial femur surface, comprising at least one of an artificial medial and lateral femur surface, adapted to contact the tibia surface or an artificial replacement therefore.
In another embodiment the medical device has said beyond part in it's beyond extension from the surrounding part of the artificial femur surface, beyond the special equatorial plane of the equatorial half of the condyle, when implanted in the knee joint, is adapted to have one or more beyond parts related to the circumferential extension of the artificial femoral surface, the beyond parts is furthermore adapted to extend in different or similar lengths, in all cases adapted to be mounted around the femur condyle beyond the equatorial half of the condyle in such a way that the beyond parts fixates the artificial femur surface onto the at least one femur condyle.
Said beyond parts may comprise at least one first beyond part plus one or more further beyond part, wherein if a curved line is interconnecting said beyond parts circumferentially following the artificial femur surface, without connecting back to the first beyond part again, from the beginning of the first beyond part to the end of the last beyond part, the total circumferential extension is more than 180°.
The hollow medical device may have the opening adapted to be fitted with the femur condyle, at least partly in proximal direction, wherein the center axis of the central part of the medical device, extends out from the hollow medical device in the opening and is adapted to be centered in said opening, at least in dorsal to frontal direction.
The center axis may be adapted to be centered perpendicularly to said center axis in said smallest opening, along said center axis, at least in dorsal to frontal direction.
A surgical method of implanting a medical device in a knee joint is further provided. The method comprising the steps of: cutting the skin of a human patient, dissecting an area of the knee joint, introducing the medical device according to claim 1 into the knee joint, attaching the medical device such that said medical device clasps a portion of a bone of the knee joint.
An arthroscopic method of implanting a medical device in a knee joint is further provided, the method comprising the steps of: inserting at least one needle or a tube like instrument into the patient's knee joint, using the needle or tube like instrument to fill the joint with a fluid, placing at least two arthroscopic trocars in the joint or inserting the camera and at least one dissecting tool direct into the knee joint, inserting said camera through one of the arthroscopic trocars or direct into the knee joint, inserting said at least one dissecting tool through one of the at least two trocars or direct into the knee joint, introducing the medical device according to claim 1 into the knee joint, attaching the medical device such that said medical device clasps a portion of a bone of the knee joint.
According to one embodiment the method further comprises the step of fixating the medical device to a portion of a bone of the knee joint using a fixation element selected from a group consisting of: at least one screw, at least one pin, at least one portion of at least one of the parts adapted to be introduced into the other part, the parts being adapted to be sliding into the other part, form fitting, welding, adhesive, pin, wire, a ball mounted into a bowl being portions of said parts, a male portion of one part mounted into a female portion of the other part, a key introduced into a lock being portions of said parts, band, and other mechanical fixation elements.
The method could further comprise the step of fixating said medical device to a portion of a bone of the knee joint using a through-going fixation element.
The method could further comprise the step of fixating the medical device to a portion of a bone of the knee joint using a through-going fixation element comprises fixating said through-going fixation element from the frontal part of said medical device positioned at the frontal part of the femoral bone, through the femoral bone and into the rear part of the medical device positioned on the rear part of the femoral bone.
According to another embodiment the method further comprises the step of applying an adhesive for assisting the through-going fixation element in the fixation of the medical device.
The method could furthermore comprise the step of fixating the medical device to a portion of a bone of the knee joint using a fixation element selected from a group consisting of: at least one screw, at least one pin, at least one portion of at least one of the parts adapted to be introduced into the other part, the parts being adapted to be sliding into the other part, form fitting, welding, adhesive, pin, wire, a ball mounted into a bowl being portions of said parts, a male portion of one part mounted into a female portion of the other part, a key introduced into a lock being portions of said parts, band, and other mechanical fixation elements.
The method could according another embodiment further comprise the step of fixating the medical device to a portion of a bone of the knee joint using a through-going fixation element. The step of fixating the medical device to a portion of a bone of the knee joint using a through-going fixation element could comprise fixating the through-going fixation element from the frontal part of said medical device positioned at the frontal part of the femoral bone, through the femoral bone and into the rear part of the medical device positioned on the rear part of the femoral bone.
The method could further comprise the step of applying an adhesive for assisting the said through-going fixation element in the fixation of said medical device.
According to yet another embodiment the medical device comprises at least two medical device parts, the step of introducing the medical device further comprises the steps of: introducing a first part of the medical device, introducing a second part of the medical device, and connecting said first part of the medical device to said second part of the medical device.
The medical device could comprise at least two medical device parts, and the step of introducing the medical device further comprises the steps of: introducing a first part of the medical device, introducing a second part of the medical device, and connecting said first part of the medical device to said second part of the medical device.
Please note that any embodiment or part of embodiment, feature, method, associated system, part of system described herein may be combined in any way.
The invention is now described, by way of example, with reference to the accompanying drawings, in which:
A length axis of the femoral bone is to be understood as an axis which extends in the direction of the length of the femoral bone from the proximal part of the femoral bone to the distal part of the femoral bone.
An axis of the lateral condyle and the medial condyle is to be understood as an axis which is perpendicular to a length axis of the femoral bone. The functional knee movements of a natural knee joint are performed in around an axis of the lateral and medial condyle.
Biocompatible material is to be understood as being a material with low level of immune response. Biocompatible materials are sometimes also referred to as biomaterials. Analogous is biocompatible metals a biocompatible metal with low immune response such as titanium or tantalum. The biocompatible metal could also be a biocompatible alloy comprising at least one biocompatible metal.
A metal alloy is to be understood as a mixture of two or more elements in solid solution in which the major component is a metal. A steel alloy is hence an alloy wherein one of the components is steel which in turn is an alloy of iron and carbon. A titanium alloy is hence an alloy wherein one of the components is titanium.
Elasticity is to be understood as a materials ability to deform in an elastic way.
Carrying surface and weight carrying surface is to be understood as a surface adapted to carry weight inside of said knee joint.
Form fitting is to be understood as an element having a part or section which is adapted to enable a mechanical connection of said element to at least one other element using said part or section. Form fitted structure is a structure of an element which enables form fitting. One type of form fitting clasps an element such as a human bone, the fixation is then created through said clasping.
Functional knee movements are to be understood as movements of the knee that at least partly correspond to the natural movements of the knee. On some occasions the natural movements of the knee joint might be somewhat limited or altered after knee joint surgery, which makes the functional knee movements of a knee joint with artificial surfaces somewhat different than the functional knee movements of a natural knee joint.
The functional position of an implantable medical device or prosthesis is the position in which the knee joint can perform functional knee movements.
Functional knee joint is a knee joint that can perform functional knee movements either with or without an implanted medical device or prosthesis.
Full functional size is to be understood as the size of the medical device when said medical device is implanted in the knee joint.
The medical device according to any of the embodiments could comprise at least one material selected from a group consisting of: polytetrafluoroethylene (PTFE), perfluoroalkoxy (PFA) and fluorinated ethylene propylene (FEP). It is furthermore conceivable that the material comprises a metal alloy, such as cobalt-chromium-molybdenum or titanium or stainless steel, or polyethylene, such as cross-linked polyethylene or gas sterilized polyethylene. The use of ceramic material is also conceivable, in the contacting surfaces or the entire medical device such as zirconium or zirconium dioxide ceramics or alumina ceramics. The part of the medical device in contact with human bone for fixation of the medical device to human bone could comprise a poorhouse structure which could be a porous micro or nano-structure adapted to promote the growth-in of human bone in the medical device for fixating the medical device. The porous structure could be achieved by applying a hydroxy-apatite (HA) coating, or a rough open-pored titanium coating, which could be produced by air plasma spraying, a combination comprising a rough open-pored titanium coating and a HA top layer is also conceivable. The contacting parts could be made of a self lubricated material such as a waxy polymer, such as PTFE, PFA, FEP, PE and UHMWPE, or a powder metallurgy material which could be infused with a lubricant, which preferably is a biocompatible lubricant such as a Hyaluronic acid derivate. It is also conceivable that the material of contacting parts or surfaces of the medical device herein is adapted to be constantly or intermittently lubricated. According to some embodiments the parts or portions of the medical device could comprise a combination of metal materials and/or carbon fibers and/or boron, a combination of metal and plastic materials, a combination of metal and carbon based material, a combination of carbon and plastic based material, a combination of flexible and stiff materials, a combination of elastic and less elastic materials, Corian or acrylic polymers.
In the following a detailed description of embodiments will be given. In the drawing figures, like reference numerals designate identical or corresponding elements throughout the several figures. It will be appreciated that these figures are for illustration only and are not in any way restricting the scope of the invention. Thus, any references to direction, such as “up” or “down”, are only referring to the directions shown in the figures. Also, any dimensions etc. shown in the figures are for illustration purposes.
This application describes one embodiment in which a medical device is suitable for implantation in a knee joint. The medical device comprises an artificial knee joint surface having an outer surface, being curved, creating a curved outer surface along a frontal to dorsal curved length axis following the curved outer surface. The curved length axis has a middle section, when the artificial knee joint surface is implanted in a functional position in the knee joint. The middle section is placed in the middle of the curved outer surface along the length axis, the artificial knee joint surface further comprises an inner surface. The inner surface comprises: a first point, a second point, a third point and a fourth point. The inner surface or an imaginary special extension of the inner surface comprises a fifth point, and a sixth point (shown in
The application further describes a medical device for treating knee joint osteoarthritis. The knee joint is including a contacting surface of the distal portion of the femoral bone or femur, and a tibia surface, including a contacting surface of the proximal portion of the tibia bone or tibia. The contacting surfaces at least partly contacting each other in a functional knee joint, and carries weight in the knee joint. The femur also contacts the patella in the patella femur contacting surface contacting the patella contacting surface. The femoral bone has an elongated distribution leading distally to a medial and lateral condyle of the femur, wherein a center axis of the elongated distribution of the femoral bone being the elongated femur center axis. The condyles 105, 106 are integrated in the femur 102 in an upside-down Y-configuration having one medial 106 and one lateral 105 condyle with a rounded form, towards a ball shaped condyle, integrated in the upside down Y-shaped double neck of the femur 102, the condyle having an equatorial plane dividing the condyle in half of an imaginary complete ball shaped configuration, when imagining the condyle having a complete towards a ball shape configuration also through the neck of the femur 102. The condyles 105, 106 having a center axis substantially in the centre of both the medial 106 and lateral 105 condyle, perpendicular to the elongated femur centre axis, defined as the femur condyles center axis, placed dorsally to the elongated femur center axis. The condyles 105, 106 having a part of the circumference being the femur contacting surface, extending in frontal-dorsal direction following the movement of the knee, less than 180 degrees, wherein the equatorial plane having a center axis extending perpendicularly from the center thereof, defining the condyle equatorial plane center axis. The hollow medical device comprises a central part and a surrounding part, the central part having a center axis in the center thereof, being aligned with the condyle equatorial plane center axis, wherein the surrounding part surrounding the surface of the femur condyle 105, 106 or a partly modified femur condyle surface not including the central part. The artificial knee joint surface comprising an artificial femur surface adapted to at least partly replace and replacing at least one of; the femur contacting surface of the medial condyle 106 and the femur contacting surface of the lateral femoral condyle 105 and the patella femur contacting surface, and adapted to be placed to contact, at least one of and at least a part of, the tibia contacting surface or an artificial replacement therefore and the patella contacting surface or an artificial replacement therefore, when mounted in the knee joint. The artificial femur surface is hollow and distally having at least to a part an outer surface being curved, wherein said artificial femur surface comprises at least one first beyond part extending from the surrounding part of the artificial femur surface beyond the equatorial plane of the equatorial half of the condyle, extending away from the contacting surface, on at least one of the medial 106 and lateral 105 condyle, on at least a part of the artificial femur surface. The at least one beyond is extending at least to a part on both a circumferential quarter of the equatorial plane placed; a) most dorsal and b) most frontal of the artificial femur surface, when said artificial femur surface is mounted on the femur 102 in its functional position in the knee joint. On the inner surface of the hollow artificial femur surface, the at least one first beyond part is adapted to have, a closest distance to the condyle equatorial plane center axis, being smaller than the largest distance from the inner surface of the artificial femur surface to the condyle equatorial plane center axis. The closest and longest distances are extending from both of the two circumferential quarters of the equatorial plane placed; a) most dorsal and b) most frontal of the artificial femur surface, thus adapted to create and creating a more stable position of said artificial femur surface, when mounted on said at least one of the femoral condyles 105, 106 in the functional position in the knee joint
a,b,c shows a medical device 115 constituting an artificial knee joint surface 116 according to an embodiment in which the medical device comprises multiple ring-shaped medical device parts 71. Said multiple ring-shaped medical device parts 71 are adapted to be connected to each other to form a medical device after insertion in a knee joint. According to one embodiment said medical device parts 71 are adapted to be connected to each other using mechanical connecting members 72a,b.
The principles of all of the above mentioned embodiments of the medical device could be adapted to serve as a joint surface fixated to the medial condyle and/or the lateral condyle, as well as the upper part of the tibia bone.
Please note that any embodiment or part of embodiment as well as any method or part of method could be combined in any way. All examples herein should be seen as part of the general description and therefore possible to combine in any way in general terms.
This application is a continuation of U.S. patent application Ser. No. 13/382,863 filed Jan. 6, 2012, which is the U.S. national phase of International Application No. PCT/SE10/50827, filed Jul. 12, 2010, which designates the US and claims priority to provisional applications 61/229,811, 61/229,802, 61/229,815, and 61/229,805 all filed on 30 Jul. 2009, and to Swedish Application No 09000980-4, 0900977-0, 0900975-4, and 0900971-3 all filed on Jul. 10, 2009, the entire contents of each of which are hereby incorporated by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 13382863 | Jan 2012 | US |
| Child | 18780550 | US |
