Patent ID: 12232968

DETAILED DESCRIPTION

The anatomy of the hip joint and its surroundings is further disclosed in: Marieb et al., Human Anatomy, 2003, Benjamin Cummings, San Francisco, pages 195-202 and in Moore et al., Clinically oriented anatomy, 1999, Lippincott, Williams & Wilkins, Baltimore, pages 501-653, both hereby incorporated by reference.

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.

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 articulating surfaces 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.

FIG.1shows the right leg of a human patient. The femoral bone102having a distal part comprising the lateral condyle105, the medial condyle106and an area between said lateral and said medial condyle109. The sections of the distal part of the femoral bone102comprises contacting surfaces of the knee joint. The knee joint furthermore comprises the patella101, which is a triangular bone which articulates with the femur102and covers and protects the knee joint. The knee joint also comprises the minisci107,108which are cartilaginous elements within the knee joint which serve as articulating surfaces to protect the ends of the bones from rubbing on each other. The minisci107,108also acts as shock absorbers in the knee joint, to absorb the shocks from the movement of the human patient. There are two menisci107,108in each knee, the medial meniscus107and the lateral meniscus108. In patients with osteoarthritis, the menisci107,108which acts as articulating surfaces i.e. weight carrying surfaces are worn away and, in extreme cases, bone can be exposed in the joint. The knee joint is protected by the knee joint capsule132also known as the articular capsule of the knee joint or the capsular ligament of the knee joint. The knee joint capsule132is wide and lax; thin in front and at the side; and contains the patella101, ligaments, menisci107,108, and bursae, which are small fluid-filled sacs made of white fibrous tissue. The knee joint capsule132consists of a synovial and a fibrous membrane separated by fatty deposits anteriorly and posteriorly.

FIG.2shows the left leg of a patient with dotted lines indicating the bone elements of the left leg, the femoral bone102, the tibial bone104, the fibula bone103and the patella. A bone channel B have been drilled in the bones from a frontal area of the thigh, into the femoral bone102, penetrating the first cortical bone, entering the cancellous bone of the femoral bone102reaching inside of the femoral bone, substantially in the prolongation thereof, penetrating the cortical bone of the distal end of the femoral bone102preferably in an area between the lateral and medial condyles, penetrating the cortical bone of the proximal portion of the tibial bone and entering the cancellous bone of the tibial bone104substantially in the prolongation thereof.

FIG.3ashows an anterior view of the leg of the human patient when a bone channel B has been made in the bone, for example as described with reference toFIG.2. A femoral anchoring device201have been introduced through the cortical femoral bone102into the cancellous bone of the marrow of the femoral bone102at an area proximal to the knee joint, such as an area in the mid-portion of the femoral bone102. The femoral bone anchoring device201have exited the bone marrow through the cortical bone, exiting at an area inside the normal knee joint, here shown as an area between the lateral and medial condyle. The femoral anchoring device shown inFIG.3acomprises an artificial knee joint surface204acreating at least a part of an artificial knee joint. However, in other embodiments, the femoral anchoring device201could be used as a support for at least one artificial knee joint surface, or as a support for at least one artificial knee joint cruciate ligament.

In the embodiment shown inFIG.3aa tibial anchoring device205have further been introduced through the cortical tibial bone104into the cancellous bone of the marrow of the tibial bone104at an area distal to the knee joint, such as an area in the mid-portion of the tibial bone104. The tibial bone anchoring device205have exited the bone marrow through the cortical bone exiting at an area inside the normal knee joint, here shown as an area centrally of the tibial plateau. The tibial anchoring device shown inFIG.3acomprises an artificial knee joint surface204bcreating at least a part of an artificial knee joint. However, in other embodiments, the tibial anchoring device201could be used as a support for at least one artificial knee joint surface, or as a support for at least one artificial knee joint cruciate ligament,

According to the embodiment shown inFIG.3a, the femoral bone anchoring device201and the tibial bone anchoring device205are adapted to be movably connected to each other for forming an artificial knee joint by means of the femoral anchoring device comprising an artificial knee joint surface204aand the tibial bone anchoring device comprising an artificial knee joint surface204b. The artificial knee joint placed centrally in the natural knee joint assists or replaces the natural knee joint such that the knee joint could be relieved by the artificial joint if weakened, or replaced by the artificial knee joint if the natural knee joint is worn. The femoral201and tibial205anchoring members provide a stable anchoring of the artificial knee joint which if needed may additionally be supported by an adhesive such as bone cement.

According to one embodiment (not shown) one of the tibial205and femoral201anchoring devices are adapted only to be fixated to a first cortical bone of the area of the knee joint, the surface of which facing a central position of the knee joint. This embodiment could be conceivable for example in embodiments where the entire bone anchoring device is entering the femoral or tibial bone though a single hole, i.e. the femoral anchoring device and the tibial anchoring device being pre-mounted to each other including the artificial knee joint204a/204bplaced between the femoral anchoring device201and tibial anchoring device205.

In alternative embodiments, the artificial knee joint placed between the femoral anchoring device201and the tibial anchoring device205is a separate member movably connected to the tibial anchoring device205and the femoral bone anchoring device201.

The femoral anchoring device201according to the embodiment shown inFIG.3afurther comprises second joints203a,203ballowing movement between a first208a,209aand second208b,209bportion of the femoral and tibial bone anchoring device, respectively.

FIG.3bshows the leg of a patient in section, when a medical device comprising a femoral anchoring device201and a tibial anchoring device205have been placed in a bone channel B. According to the embodiment shown inFIG.3bthe bone channel have been created from one direction and the channel crating member have entered the cortical bone of the femoral bone102in one position only and thus creating the channel B as further disclosed with reference toFIG.2.

The medical device comprising the femoral bone anchoring device201and tibial bone anchoring device have been placed in the channel B through the entry hole in the cortical bone of the femoral bone. The medical device is either pre-mounted, such that the femoral anchoring device and the tibial anchoring device is pre-mounted to each o to each prior to the introduction of the medical device into the hole in the femoral bone102. According to the embodiment shown inFIG.3bthe femoral anchoring device201and the tibial anchoring device205are movably connected to each other for forming an artificial knee joint by means of the femoral bone anchoring device201comprising an artificial knee joint surface204aand the tibial bone anchoring device205comprising an artificial knee joint surface204b. The artificial knee joint placed centrally in the natural knee joint assists or replaces the natural knee joint such that the knee joint could be relieved by the artificial joint if weakened, or replaced by the artificial knee joint if the natural knee joint is worn. The femoral201and tibial205bone anchoring devices provide a stable anchoring of the artificial knee joint which if needed may additionally be supported by an adhesive such as bone cement.

InFIGS.3aand3bthe femoral201and tibial205bone anchoring devices are fixated to the inside of the femoral and tibial bones respectively by radius adjustment devices202or expanding members202adapted to adjust the maximum radius substantially transverse or at least clearly angled in relation to a center axis of the bone anchoring device, for fixating the femoral201and tibial205bone anchoring device towards the cortical bone, from the inside of the bone along the elongated portions. The details of the radius adjustment devices are described in further detail with reference toFIGS.16a-19b.

FIGS.4aand4bshows the anchoring devices201,205in an embodiment similar to the previously described with reference toFIGS.3aand3bwith the difference that in4a,4b, the bone channels B have been created both from above, entering the femoral bone102, and from below, entering the tibial bone104, which enables the introduction of the tibial bone anchoring device205through the hole in the tibial bone104and the introduction of the femoral bone anchoring device201through the hole in the tibial bone104, in which case the femoral bone anchoring device201having an artificial femoral joint surface and the tibial bone anchoring device205having an artificial tibial joint surface meet centrally in the natural knee joint for either connecting to an additional part for forming the artificial joint, or by simply connecting to each other for forming the artificial knee joint.

FIGS.5aand5bshows the second joints203a,203bin further detail. The second joint203a,ballows movement between a first208a,209aand second208b,209bportion of the femoral and tibial bone anchoring device, respectively. The second joint could enable the precise adjustment of the position of the artificial knee joint comprised of surfaces204a,bof the femoral bone anchoring device201and the tibial bone anchoring device201. The adjustment could be of great importance since the center of rotation needs to be in the right location for the movement of the artificial knee joint to correspond with the natural movements of the natural hip joint. The second joints could be manually adjustable for example by means of a tool reaching the device through the bone channel B, or using electrical means such as a motor or a solenoid built into the femoral and/or tibial bone anchoring device respectively. The electrical means could be operated using an implantable battery which could communicate via a control unit with a remote or wired control to the outside of the patient. In alternative embodiments the electrical means are operated by means of direct operation in the form of wireless energy, such as magnetic force or induction affecting the electric means being part of the femoral201and/or tibial205anchoring devices respectively.

FIG.6shows the medical device in an embodiment similar to the embodiment shown with reference toFIG.5bwhen the second joints203a,203bhave been used to position the artificial knee joint comprised of the joint surfaces of204a,204bof the femoral bone anchoring device201and the tibial bone anchoring device205.

FIG.7ashows the a posterior view of a leg of a human patient when medical device for creating an artificial knee joint has been implanted. The medical device comprises a transversal member221adapted to be placed through four layers of cortical bone111a,111b,111cand111dof the distal portion of the femoral bone102, out of the totally four cortical layers along the prolongation of the transversal member221. The transversal member221is adapted to be involved in the artificial knee joint placed centrally between the lateral and medial condyle. The transversal member221comprises at least one fixation portion adapted to be involved in fixation of the transversal member221to at least one of the four layers of femoral cortical bone111a-d. In the embodiment shown inFIG.7aone end of the transversal member221comprises a fixed stop226, whereas the other end of the transversal member221comprises a threaded portion to which a nut225is attached for fixating the transversal member in the hole though the four layers of cortical bone111a-d.

According to the embodiment shown inFIG.7athe transversal member221is adapted to be involved in the artificial joint positioned between the lateral and medial condyle and positioned between the normal lateral and medial joint surfaces cranial to the natural joint surfaces of the knee joint.

According to the embodiment shown inFIG.7athe transversal member221comprises the center of rotation and is partially encircled by a portion of a tibial anchoring member205having a U-shaped portion222adapted to articulate with the transversal member for creating the artificial knee joint.

In other embodiments (not shown) the transversal member221is adapted to comprise an artificial knee joint holding part adapted to be involved in holding the artificial knee joint, in which case the artificial knee joint comprises of additional pats.

FIG.7bshows the tibial bone anchoring device205in further detail comprising the U-shaped portion222adapted to articulate with the transversal member221for crating the artificial knee joint. The tibial bone anchoring device205comprises radius adjusting members202or expanding members202adapted to adjust the maximum radius substantially transverse or at least clearly angled in relation to a center axis of the tibial bone anchoring device205, for fixating the tibial bone anchoring device205towards the cortical bone, from the inside of the bone along the elongated portions. According to the embodiment shown inFIG.7b, the radius adjustment members202are operated by electrical means such as a motor or a solenoid built into the tibial bone anchoring device205. The electrical means could be operated using an implantable battery which could communicate via a control unit with a remote control212on the outside of the patient. In alternative embodiments the electrical means are operated by means of direct operation in the form of wireless energy, such as magnetic force or induction affecting the electric means being part of the tibial205anchoring device. The details of the radius adjustment devices are described in further detail with reference toFIGS.16a-19b.

FIG.8ashows an embodiment similar to the embodiment described with reference toFIG.7a, with the difference that the transversal member221is adapted to be placed through three layers of cortical bone111a-cof the distal portion of the femoral bone102and be fixated to a fourth layer111dby means of a threaded portion227aadapted for fixation in bone.

The tibial anchoring member205shown inFIG.8bis identical to the tibial anchoring member ofFIG.7b, and thus have a construction that is independent of the fixation of the transversal member.

FIG.9ashows an embodiment similar to the embodiment described with reference toFIG.7a, with the difference that the transversal member221is adapted to be placed through two layers of cortical bone111a-bof the distal portion of the femoral bone102and be fixated to a third layer111cby means of a threaded portion227aadapted for fixation in bone.

The tibial anchoring member205shown inFIG.9bis identical to the tibial anchoring member ofFIG.7b, and thus have a construction that is independent of the fixation of the transversal member.

FIG.10ashows an embodiment of the medical device similar to the embodiment shown with reference toFIGS.7a,8aand9a, with the difference that the medical device further comprises a femoral bone anchoring device201for further stabilizing the artificial knee joint comprised of the transversal member221and the tibial bone anchoring device205. The femoral bone anchoring device201is similar to the femoral bone anchoring devices described with reference toFIGS.3a-6, with the difference that the most distal portion222aof the tibial bone anchoring device205is U-shaped and adapted to articulate with around a center of rotation located at the transversal member221. The U-shaped proximal portion222aof the tibial bone anchoring device is adapted to interact with the U-shaped portion of the distal portion of the femoral bone anchoring device201and in some embodiments the proximal portion222aof the tibial bone anchoring member and the distal portion222bof the femoral anchoring member could comprise articulating surfaces such that the proximal portion222aof the tibial bone anchoring member205and the distal portion222bof the femoral anchoring member201could contact each other and articulate and function as joint surfaced of the knee joint supporting the surfaces of the proximal portion222aof the tibial bone anchoring member205and the distal portion222bof the femoral bone anchoring member201articulating with the transversal member221. The artificial knee joint may of course comprise many different technical solutions and the herein supplied constructions is only examples.

FIG.10bshows the embodiment of the medical device described with reference toFIG.10in a medial view further showing the leg of the patient in section. In the embodiment shown inFIG.10b, the center of rotation is positioned in the area of the transversal member221such that rotating around the transversal member221corresponds to the movement of the natural knee joint.

FIG.11shows an embodiment in which the transversal member221is fixated through four layers of cortical bone (as further disclosed with reference toFIG.7a). In the embodiment shown inFIG.11the transversal member221is used to fixate artificial knee joint surfaces231a,badapted to at least partially replace the natural knee joint surfaces. The artificial knee joint surfaces231a,bare adapted to be fixated by means of fixating portions232that enters the cancellous bone of the femoral bone and such that the transversal member221can penetrate a first layer of cortical bone, a fixating portion232of a first artificial knee joint surface231a, a second layer of cortical bone, exiting into the area between the lateral and medial condyles, entering and penetrating a third layer of cortical bone, penetrating a fixating portion232of a second artificial knee joint surface231band penetrating a fourth layer of cortical bone for providing a stabile fixation of the artificial knee joint surfaces231a,b. In the embodiment shown inFIG.11one end of the transversal member221comprises a fixed stop, whereas the other end of the transversal member221comprises a threaded portion to which a nut is attached for fixating the transversal member in the hole though the four layers of cortical bone, however it is equally conceivable that the transversal member221is adapted to be placed through three layers of cortical bone of the distal portion of the femoral bone102and be fixated to a fourth layer by means of a threaded portion adapted for fixation in bone, as is further described with reference toFIG.8a. The transversal member provides a very stabile fixation of the artificial knee joint surfaces231a,231b, however, if additional fixation is required an adhesive such as bone cement could be used to provide additional fixation. The transversal member221may be used to fixate the artificial knee joint surface both at the medial condyle231bseparate or lateral condyle231aseparate. The transversal member may in this case only be fixated to the two cortical bones on each side of the lateral or medial condyle, although this embodiment is not the preferred choice. Furthermore the transversal member may be used to fixate an artificial patella knee surface in the area between the medial and lateral condyle as well (not shown).

FIG.12ashows the medical device according to an embodiment in which a portion of the femoral and/or tibial bone anchoring device comprises a material or part of material having variable elasticity. In the embodiments shown inFIG.12athe portion242of the of the femoral bone anchoring device201comprising material or part of material having variable elasticity have a core portion242being less elastic that the surface portion244, whereas the portion241of the tibial bone anchoring device205comprising material or part of material having variable elasticity comprises a plurality of portions having variable elasticity. The loosening or anchoring members in bone could be induced by an abnormal strain being placed on the hip joint from e.g. the patient falling or making a rapid movement of the hip. Most anchoring devices are made from a material harder than the bone in which they are anchored, which adds to the tension created between the anchoring devices and the bone of the patient. The portion241comprises several sections, schematically denoted I-VII. According to this embodiment the portion241is made of a metallic material, which is hardened so that the different sections have different properties. The hardening process can be performed in a way so that there are clear sections with different properties, however it is also conceivable that said different properties propagates the portion241/242continuously i.e. there are no clear boarders, rather continuously varying properties throughout the portion241/242. According to other embodiments the material is a polymer material hardened or stretched to create different properties in the different sections of the hip joint prosthesis. According to other embodiments the hip joint prosthesis is made of ceramic or powder based material, in which case the hip joint prosthesis can be hardened or sintered to produce different properties in the different sections extending along a length axis of the portion241/242. The proximal section III-V are preferably more elastic for allowing the artificial knee joint fixated to the tibial bone anchoring device205to move slightly in relation to the fixating portions comprising the radius adjusting members222placed more distal in the tibial bone104. The distal portions I-II of the portion241is preferably less elastic for interacting with the less elastic material of the distal portion of the tibial bone anchoring device205. This varying elasticity may play an important role as a tool for chock absorbing forces towards the bone. The construction may be done in many different ways to achieve the same goal. Preferable this construction will be combined with the radius adjustment devices disclosed in for example inFIGS.3aand3bshowing the femoral201and tibial205bone anchoring devices fixated to the inside of the femoral and tibial bones respectively by the radius adjustment devices202or expanding members202towards the cortical bone, from the inside of the bone along different portions of the bone adjustment devices. The details of the radius adjustment devices or expanding members are also described in further detail with reference toFIGS.16a-19b. These radius adjustment devices or expanding members are preferable using the technology of varying elasticity. Similar result as with the varying elasticity could also be achieved by any kind of suspension including spring suspension and the construction may also be bendable or flexible achieving the same result, seeFIG.16a-19b.

FIG.12bshows the medical device comprising portions241/242having varying elasticity in a side view. The varying elasticity could be very advantageous for absorbing large strains induced for example by the patient falling. The portions241/242with varying elasticity could be used in any one of the embodiments disclosed herein.

FIG.13a,13bshows an embodiment of the medical device similar to the embodiment previously described with reference toFIGS.3a,3b, in a posterior and medial view, respectively. The difference being that the distal portion251of the femoral bone anchoring device201comprises an artificial cruciate ligament holding part251adapted to hold an artificial cruciate ligament253, which in turn is adapted to stabilize the knee joint. Furthermore the proximal portion252of the tibial bone anchoring device205comprises an artificial cruciate ligament holding part252and the artificial cruciate ligament253is thus kept in place by the cruciate ligament holding part251of the distal portion of the femoral bone anchoring device201and the proximal portion252of the tibial bone anchoring device205. By using the femoral and tibial anchoring devices201,205for holding the artificial cruciate ligament253the artificial cruciate ligament is kept in place by stable anchoring devices. The bone anchoring devices201,205could be adapted to hole an anterior artificial cruciate ligament or a posterior artificial cruciate ligament, or the bone anchoring devices201,205could be adapted such that both the anterior and posterior artificial cruciate ligament could be fixated to the anchoring devices201,205. Preferable mounted on different positions especially in anterior posterior direction.

FIG.14shows an embodiment in which the transversal member221(as previously disclosed with reference toFIGS.7a,8a,9a,10a,11and12a) are adapted to fixate an artificial cruciate ligament253, which could be an anterior artificial cruciate ligament or a posterior artificial cruciate ligament, or both the anterior and posterior artificial cruciate ligament. Preferable mounted on different positions both in anterior posterior direction and medial lateral direction. The support part256may be extended in different directions. The transversal member provides a stable fixation member for the artificial cruciate ligament253, which in the other end is fixated to a tibial bone anchoring device205. In alternative embodiments the cruciate ligament is the natural cruciate ligament and the transversal member221only supports the movement of the natural cruciate ligament. In yet other alternatives the cruciate ligament is a portion of the patella tensor used to create a “natural” artificial cruciate ligament.

FIG.15shows an embodiment in which the artificial cruciate ligament at the proximal end is fixated to a femoral bone anchoring device201comprising a cruciate ligament holding part251, and the distal end of the artificial cruciate ligament is fixated to in or through a bone channel B2. In the embodiment shown inFIG.15the cruciate ligament253is fixated by means of a fixation button, such that the cruciate ligament253is hindered from moving back into the bone channel B2.

FIG.16ashows a radius adjustment member for fixating the bone anchoring members (201,205throughout the application) to the inside of the cortical bone of the patient. The a radius adjustment member comprising an expanding portion654, and a bone contacting surface655on the expanding portion654. The expanding portion654is adapted to be at least partially inserted into the bone of a patient and to expand within the bone such that the bone contacting surface655is placed in contact with the inside of the bone for fixating the bone anchoring device to the inside of the bone. The radius adjustment member has a centrally placed longitudinal axis and the expanding portion654comprises a plurality of expansion members658a-d, adapted to expand radially away from the longitudinal axis656. One advantage with using the radius adjustment member is that bone cement, normally used for fixation purposes, could create a bodily macrophage reaction excavating the bone cement and thus causing loosening of the fixation. Other fixations, such as fixations using orthopedic screws penetrating the bone could also create a bodily reaction rejecting the foreign matter of the medical device. Eliminating the use of bone cement and orthopedic screws, and at the same time creating a stabile fixation would be very advantageous, furthermore, creating a fixation that has the ability to move slightly in the fixation in response to exposure to force e.g. from the patient falling would be even more advantageous.

The radius adjustment member according to the embodiment shown inFIG.16a/16bfurther comprises an operating device659adapted to operate the expanding portion564, according to the embodiment shown inFIG.16a,16bthe operating device659comprises a conical member659adapted to contact a corresponding surface660of the expanding portion654for expanding the expanding portion654. The operating device659further comprises a rotatable threaded portion661adapted to engage a corresponding threaded portion of the conical member659for moving the conical member659along the centrally placed longitudinal axis656in the direction of the connecting portion653. The threaded portion661is a portion of an elongated member662, which according to the embodiment shown inFIG.3a,3breaches from the end portion657to the top part of the prosthetic contacting portion45having a tool engaging portion663, such that the elongated member662can be rotated using a tool for rotating the threaded portion and thereby the moving the conical member659. According to other embodiments, the operating device could be operated using electrical means such as a motor or a solenoid built into the bone anchoring device. The electrical means could be operated using an implantable battery which could communicate via a control unit with a remote or wired control to the outside of the patient. In alternative embodiments the electrical means are operated by means of direct operation in the form of wireless energy, such as magnetic force or induction affecting the electric means.

The bone contacting surfaces655, according to the embodiments shown inFIG.16a,16bcomprise needle or nail like tapered members664adapted to at least partially enter the bone of the inside thereof for further fixating the bone anchoring device in the bone, especially axially along the centrally placed longitudinal axis656. In other embodiments, not shown, the bone contacting surface comprises a porous micro- or nano-structure adapted to promote the in-growth of bone in the medical device. The bone contacting surface655is here described in relation to the embodiment ofFIGS.16aand16b, however the adaptation of the bone contacting surface655is equally applicable in all of the embodiments disclosed herein.

FIG.16bshows the radius adjustment member according to the embodiment shown inFIG.16awhen the elongated member662has been rotated by means of a tool or electrical means such that the threaded portion661has moved the conical member659affecting the corresponding surface of the expansion members658a-dand thus expanding the expanding portion654such that the bone contacting surface655is adapted to be placed in contact with the inside of the femoral bone.

FIGS.17aand17bshows the medical device in an embodiment similar to the embodiment disclosed with reference toFIGS.16aand16b, however in the embodiment ofFIGS.17aand17bthe operation device of the medical device further comprises an elastic operation device680adapted to press on the conical member659for expanding the expanding portion654. The elastic member could be adapted to be released after the insertion of the radius adjustment member into the bone5thereby creating an elastic pressure on the expansion members658a,658bfor elastically pressing the bone contacting surfaces655onto the inside of the bone. The elastic operation device680is according to the embodiment shown inFIGS.17aand17breleased by turning the elongated member662with a tool or electric means engaging the tool engaging portion663. The elastic portion enables a fixation of the radius adjustment member to the bone that has the ability to move slightly in the fixation in response to exposure to force e.g. from the patient falling. In the embodiment shown inFIGS.17aand17bthe elastic operation device680is a spring which could be a linear spring or a non-linear spring allowing a first movement with a first elasticity and further movement with a second elasticity that requires greater force. The elastic operation device could according to other embodiments comprise an elastic material, such as an elastomer.

FIG.17bshows the medical device when the elastic operation device680has been released such that the expanding portion has been expanded pressing the bone contacting surfaces against the inside of the bone.

FIGS.18aand18bshows the radius adjustment member according to an embodiment in which the expanding portion654comprises a deformable expanding portion654, wherein the expanding portion expands by the deformable expanding portion654deforming, such that the bone contacting surface655is placed in contact with the inside of the femoral bone for fixating the radius adjustment member to the femoral bone. The deformable expanding portion654deforms at deformation points684by the threaded member661pulling the end portion657towards the connecting portion653thus expanding the expanding portion654pushing the bone contacting surfaces655radially such that they are placed in contact with the inside of the bone.

FIG.18bshows the medical device when the deformable expanding portion654has expanded pressing the bone contacting surfaces655against the inside of the bone.

FIG.19ashows the radius adjustment member according to an embodiment in which the radius adjustment member has a centrally placed longitudinal axis656, wherein the radius adjustment member comprises a plurality of expanding portions654a-d, distributed axially along the longitudinal axis656of the medical device. The plurality of expanding portions654a-ddistributed axially along the longitudinal axis656of the radius adjustment member is adapted to radially expand independently of each other, to allow different expansion of the different expanding portions654a-d. The different expansion could allow the expanding portions654a-dto adapt to the uneven surfaces of the anatomy of the inside of the bone. Since the different expanding portions expand independently of each other, one expanding portion654awill expand until the bone contacting surface655of that particular expanding portion is placed in contact with the bone of the inside of the bone, after which the other expanding portions654b-dwill continue to expand until their respective bone contacting surface is placed in contact with the inside of the bone. Each expanding portion comprises four expansion members658a-deach having a sloped surface660corresponding to a sloped surface696of the conical members659, such that the conical members presses the expansion members radially from the longitudinal axis656when the conical members659are moved in the direction of the connecting portion653.

FIG.19bshows the medical device when the expanding portions654a-dhas been expanded for pressing the bone contacting surfaces655against the inside of the 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.