Classifications

• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
  • A61F2/02—Prostheses implantable into the body
  • A61F2/30—Joints
  • A61F2/32—Joints for the hip
  • A61F2/36—Femoral heads ; Femoral endoprostheses
  • A61F2/3601—Femoral heads ; Femoral endoprostheses for replacing only the epiphyseal or metaphyseal parts of the femur, e.g. endoprosthetic femoral heads or necks directly fixed to the natural femur by internal fixation devices
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
  • A61F2/02—Prostheses implantable into the body
  • A61F2/30—Joints
  • A61F2/32—Joints for the hip
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B17/00—Surgical instruments, devices or methods, e.g. tourniquets
  • A61B17/16—Bone cutting, breaking or removal means other than saws, e.g. Osteoclasts; Drills or chisels for bones; Trepans
  • A61B17/1662—Bone cutting, breaking or removal means other than saws, e.g. Osteoclasts; Drills or chisels for bones; Trepans for particular parts of the body
  • A61B17/1664—Bone cutting, breaking or removal means other than saws, e.g. Osteoclasts; Drills or chisels for bones; Trepans for particular parts of the body for the hip
  • A61B17/1666—Bone cutting, breaking or removal means other than saws, e.g. Osteoclasts; Drills or chisels for bones; Trepans for particular parts of the body for the hip for the acetabulum
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B17/00—Surgical instruments, devices or methods, e.g. tourniquets
  • A61B17/56—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor
  • A61B17/58—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor for osteosynthesis, e.g. bone plates, screws, setting implements or the like
  • A61B17/68—Internal fixation devices, including fasteners and spinal fixators, even if a part thereof projects from the skin
  • A61B17/74—Devices for the head or neck or trochanter of the femur
  • A61B17/742—Devices for the head or neck or trochanter of the femur having one or more longitudinal elements oriented along or parallel to the axis of the neck
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
  • A61B17/00—Surgical instruments, devices or methods, e.g. tourniquets
  • A61B17/56—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor
  • A61B17/58—Surgical instruments or methods for treatment of bones or joints; Devices specially adapted therefor for osteosynthesis, e.g. bone plates, screws, setting implements or the like
  • A61B17/68—Internal fixation devices, including fasteners and spinal fixators, even if a part thereof projects from the skin
  • A61B17/84—Fasteners therefor or fasteners being internal fixation devices
  • A61B17/86—Pins or screws or threaded wires; nuts therefor
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
  • A61F2/02—Prostheses implantable into the body
  • A61F2/30—Joints
  • A61F2/32—Joints for the hip
  • A61F2/34—Acetabular cups
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
  • A61F2/02—Prostheses implantable into the body
  • A61F2/30—Joints
  • A61F2/32—Joints for the hip
  • A61F2/36—Femoral heads ; Femoral endoprostheses
  • A61F2/3609—Femoral heads or necks; Connections of endoprosthetic heads or necks to endoprosthetic femoral shafts
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
  • A61F2/02—Prostheses implantable into the body
  • A61F2/30—Joints
  • A61F2002/30001—Additional features of subject-matter classified in A61F2/28, A61F2/30 and subgroups thereof
  • A61F2002/30108—Shapes
  • A61F2002/30199—Three-dimensional shapes
  • A61F2002/30224—Three-dimensional shapes cylindrical
  • A61F2002/30235—Three-dimensional shapes cylindrical tubular, e.g. sleeves
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
  • A61F2/02—Prostheses implantable into the body
  • A61F2/30—Joints
  • A61F2002/30001—Additional features of subject-matter classified in A61F2/28, A61F2/30 and subgroups thereof
  • A61F2002/30316—The prosthesis having different structural features at different locations within the same prosthesis; Connections between prosthetic parts; Special structural features of bone or joint prostheses not otherwise provided for
  • A61F2002/30329—Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements
  • A61F2002/30405—Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements made by screwing complementary threads machined on the parts themselves
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
  • A61F2/02—Prostheses implantable into the body
  • A61F2/30—Joints
  • A61F2002/30001—Additional features of subject-matter classified in A61F2/28, A61F2/30 and subgroups thereof
  • A61F2002/30621—Features concerning the anatomical functioning or articulation of the prosthetic joint
  • A61F2002/30639—Features concerning the anatomical functioning or articulation of the prosthetic joint having rolling elements between both articulating surfaces
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
  • A61F2/02—Prostheses implantable into the body
  • A61F2/30—Joints
  • A61F2/30767—Special external or bone-contacting surface, e.g. coating for improving bone ingrowth
  • A61F2/30771—Special external or bone-contacting surface, e.g. coating for improving bone ingrowth applied in original prostheses, e.g. holes or grooves
  • A61F2002/30795—Blind bores, e.g. of circular cross-section
  • A61F2002/30797—Blind bores, e.g. of circular cross-section internally-threaded
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
  • A61F2/02—Prostheses implantable into the body
  • A61F2/30—Joints
  • A61F2/30767—Special external or bone-contacting surface, e.g. coating for improving bone ingrowth
  • A61F2/30771—Special external or bone-contacting surface, e.g. coating for improving bone ingrowth applied in original prostheses, e.g. holes or grooves
  • A61F2002/30878—Special external or bone-contacting surface, e.g. coating for improving bone ingrowth applied in original prostheses, e.g. holes or grooves with non-sharp protrusions, for instance contacting the bone for anchoring, e.g. keels, pegs, pins, posts, shanks, stems, struts
  • A61F2002/30886—Special external or bone-contacting surface, e.g. coating for improving bone ingrowth applied in original prostheses, e.g. holes or grooves with non-sharp protrusions, for instance contacting the bone for anchoring, e.g. keels, pegs, pins, posts, shanks, stems, struts externally-threaded
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
  • A61F2/02—Prostheses implantable into the body
  • A61F2/30—Joints
  • A61F2/32—Joints for the hip
  • A61F2/34—Acetabular cups
  • A61F2002/348—Additional features
  • A61F2002/3493—Spherical shell significantly greater than a hemisphere, e.g. extending over more than 200 degrees
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2/00—Filters implantable into blood vessels; Prostheses, i.e. artificial substitutes or replacements for parts of the body; Appliances for connecting them with the body; Devices providing patency to, or preventing collapsing of, tubular structures of the body, e.g. stents
  • A61F2/02—Prostheses implantable into the body
  • A61F2/30—Joints
  • A61F2/46—Special tools or methods for implanting or extracting artificial joints, accessories, bone grafts or substitutes, or particular adaptations therefor
  • A61F2002/4635—Special tools or methods for implanting or extracting artificial joints, accessories, bone grafts or substitutes, or particular adaptations therefor using minimally invasive surgery
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2220/00—Fixations or connections for prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof
  • A61F2220/0025—Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2230/00—Geometry of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof
  • A61F2230/0063—Three-dimensional shapes
  • A61F2230/0069—Three-dimensional shapes cylindrical
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
  • A61F2310/00—Prostheses classified in A61F2/28 or A61F2/30 - A61F2/44 being constructed from or coated with a particular material
  • A61F2310/00005—The prosthesis being constructed from a particular material
  • A61F2310/00011—Metals or alloys
  • A61F2310/00023—Titanium or titanium-based alloys, e.g. Ti-Ni alloys

Definitions

• the present invention relates to a hip joint prosthesis for permanent anchoring in the human hip joint, which prosthesis consists of a first joint unit designed to be anchored in the neck of a human femur and a second joint unit designed to be anchored in the human pelvis, in which respect the first joint unit comprises a joint head and an anchoring arrangement for anchoring the joint head in the femur, and the second joint unit comprises a socket with a concave joint surface shaped and dimen ⁇ sioned to bear against and to articulate under sliding contact with the joint head, and an anchoring arrangement for anchoring the socket in a cavity in the pelvis, the anchoring arrangement in the femur comprising at least one sleeve-shaped anchoring element and at least one tightening element connected to the joint head in order to create, by engaging with the anchoring element, a prestressable anchoring of the joint head with the tightening element introduced into the sleeve-shaped anchoring element.
• prostheses intended for anchoring by means of bone cement and, on the other hand, prostheses intended for cement-free anchoring by screwing into the bone tissue or by creating primary fixation by means of a positive lock in another way, and at the same time creating the preconditions for further consolidation by bone tissue growing into the porous surface structures of the associated prosthesis components.
• the stem length has varied between 10 and 30 cm.
• the stems of the cement- free prosthesis systems have had a surface structure for osseous in-growth either along the entire stem or along only parts thereof.
• Patent publication DE A 2,845,231 discloses a prosthesis in which respect it is assumed that anchoring of the joint ball unit is obtained by direct osseous in-growth in porous surface structures.
• the known prosthesis has a non-threaded anchoring sleeve which is so short that the main part of a shaft incor ⁇ porated in the joint ball unit makes bone contact, and this means that joint surface replacement must be effec ⁇ ted in a single stage with simultaneous assembly of both an anchoring arrangement and the joint ball unit.
• the preconditions for this type of unique anchoring have been shown to be the use of commercially pure titanium as metal component with unique biocompatibility and cor- rosion resistance, combined with a controlled and atrau- atic operating technique, and the avoidance of direct loading by means of the implant being inserted in a 2- stage procedure in which an anchoring element is simply implanted in the first stage and is only coupled to a loaded function element in a second operation.
• One aim of the present invention is to provide a hip joint prosthesis which is based on the experiences from - 5 -
• the aim is, therefore, to create an osseointegrated hip joint prosthesis in which the metal component consists of titanium and in which anchoring element and function element are introduced in separate operating stages with a load-free interval of at least 3 months.
• the metal component consists of titanium
• anchoring element and function element are introduced in separate operating stages with a load-free interval of at least 3 months.
• it is of course intended, in the first place, to create the conditions for a satisfactory anchoring stability which will make it possible to extend the indications for hip prosthesis surgery to more active and younger individuals than has been the case up till now, but a further aim is to reduce the theoretical risks related to the transport of toxic metal ions from the prosthesis material to the body tissues.
• the metal alloys used in prosthesis systems in clinical use today offer a good compromise as regards satisfying requirements for mechanical strength, wear resistance, corrosion resistance and production economy, important objections can theoretically, be raised as regards their biocompatibility properties.
• the alloy substances such as chromium, cobalt, nickel, aluminium and vanadium, are thus potentially toxic, even though it has not been possible to elucidate the threshold value for toxic and allergic reactions to these metals.
• there are only 10 or so reported cases in which there has been cause to suspect a connection between development of cancer and the use of prostheses of cobalt-based alloy but there is nevertheless concern that this type and other types of complications are essentially increasing in parallel with the increasing use of prosthesis systems for the large joints of the body.
• One aim of the present invention is to produce a hip joint prosthesis by means of which the surgical defect in prosthetic surgery is reduced, i.e. the cutting of intact bone tissue in connection with the operation can be reduced by preserving a large part of the femoral neck.
• the said aims are achieved by means of a hip joint prosthesis according to the present invention, which is characterized in that the sleeve-shaped anchoring element with a grooved outer surface is designed to be separately implanted in a channel passing through the femoral neck and to extend essentially over the entire length thereof in order to form an anchorage in the femur via the said outer surface and to form a guide for the tightening .
• the tightening element comprises a head and is designed to be axially introduced into the associated sleeve-shaped anchoring element and connected to the joint head.
• Figs, la and lb show exploded views in section of the components incorporated in a first embodiment of the hip joint prosthesis according to the present invention.
• Fig. 2 shows a perspective view of the joint ball unit incor ⁇ porated in the prosthesis.
• Figs. 3 - 11 show schemati- cally the procedure for assembly of the hip joint pros ⁇ thesis according to Figs, la and lb, while Figs. 12 - 18 show, on a larger scale, partially broken perspective - 7 -
• FIG. 19 shows a hip joint provided with the hip joint prosthesis in the first embodiment according to the present invention.
• Fig. 20 shows the hip joint pros- thesis in a second embodiment.
• Figs. 21 - 24 show the different stages in the implantation of the prosthesis according to Fig. 20, and Figs. 25 and 26 show two further embodiments of the prosthesis according to the invention.
• the design of the hip joint prosthesis in the first embodiment emerges most clearly from Fig. la. Fig. 2 and Fig. 16.
• the prosthesis consists of two main units - on the one hand a ball unit 1 intended to be anchored in a subject's femur 2 and, on the other hand, a socket unit
• the ball unit 1 consists of a ball 5 and an anchoring arrangement, comprising an anchoring element 6 and a screw connection in the form of a threaded pin 7 projecting out from the ball 5 and a threaded screw bushing 8.
• the ball 5 is made, for example, of titanium and has a convex joint surface 9 which has the shape of a partial sphere, essentially an approximated semisphere with an essentially cylindrical cavity 10, which is open in the direction away from the joint surface 9.
• the cylindrical inner wall 11 of the cylindrical cavity 10 is designed with profiling, in the illustrated example in the form of ribs 12 in order to permit secure positive locking against the femoral neck 13 with deformation of its surface.
• the ribs extend in the axial direction parallel to the longitudinal direction of the threaded pin 7, but they can also have another design such as, for example, threads for engaging with the femoral neck.
• the pin 7 extends centrally and axially relative to the cylindrical - 8 -
• the cavity 10 forms part of a shaft 14 which extends centrally and axially and projects from the base 15 of the cavity 10.
• the unthreaded part of the shaft 14 is essentially cylindrical and has a diameter which exceeds the diameter of the threaded pin 7, and its shape and dimensions are adapted to the shape and dimensions of the anchoring element 6 in such a way that the shaft 14 can be introduced into the anchoring element.
• the anchoring element 6 forms, as shown most clearly in Fig. la, a femoral neck fixture in the form of a sleeve of, for example, titanium with a grooved, for example threaded, contact surface against the bone.
• This sleeve is essentially cylindrical and has an outer wall 16, for example cylindrical, intended for anchoring in a drilled channel 17 through the femoral neck 13, and a continuous cylindrical channel 18 with a cylindrical inner wall 19 dimensioned so as to form a guide for the shaft 14 of the ball 5.
• the anchoring element 6 has, at its end distant from the ball 5, a flange 20 intended to bear against the femur 2 in an area around the outer end of the channel 17.
• the outer wall 16 of the anchoring element 6 can be profiled by means of elongate ribs or threads for good anchoring in the femoral neck.
• the screw bushing 8 is designed as an essentially cylind- rical body with a cylindrical outer wall 21, the shape and dimensions being adapted to be introduced into the channel 18 of the anchoring element 6 so as to be posi- tionally guided in the latter with good precision.
• the cylindrical wall 21 of the screw bushing is expediently given the same diameter as the shaft 14.
• the screw bushing 8 also has a central bore 23 open at one end 22 with an internal thread dimensioned to cooperate with the screw 7 of the ball 5 in order to form the screw connec ⁇ tion.
• the screw bushing 8 furthermore has a head 24 which comprises a stop surface 25 which forms an abutment against a bearing surface 26 on the flange 20 of the anchoring element 6. In the example shown, the head is - 9 -
• the socket unit 3 is designed as a double socket with a load-absorbing base socket 28 made of a strong, tissue-compatible material, such as tita- nium, and a socket made of a material which gives low friction against the ball 5, for example a wear-resistant polymer material such as high-density polyethylene.
• the socket has a concave and essentially semispherical cavity 30 whose form and dimensions are adapted to the external form and dimensions of the joint surface 9 of the ball 5.
• the concave wall 31 of the socket 29 thus forms the joint surface of the socket unit 3.
• the socket 29 has a convex and essentially semispherical fitting surface 31 intended to be introduced into a correspondingly shaped and dimensioned and essentially semispherical concave bearing surface 32 in the base socket 28.
• the socket 29 is intended to be connected to the base socket 28 by means of a positive lock which, in the example illustrated in Fig. 14, consists of a snap lock in the form of a circum- ferential rib 33 on the fitting surface 31 of the bearing socket, which rib 33 is intended to snap into a cor ⁇ responding groove 34 in the bearing surface of the base socket 28.
• the socket unit 3 (see Fig. 16) moreover comprises an anchoring arrangement 34 for anchoring the base socket 28 in the hollow 35 of the pelvis 4 adapted by pre-fo ⁇ ning to the shape of the base socket 28.
• the anchoring arrangement comprises at least one anchoring element 36 in the form of a pelvis fixture, for example of titanium, comprising a positive lock for cooperation with a central pin 37 which projects from the base socket 28.
• the anchoring arrangement 34 has a number of anchoring screws 40 (see Fig.
• the anchoring screws 40 are intended to be anchored in bores 42 formed in the hollow 35 of the . pelvis 4.
• the inside 43 of the base socket 28 is, like the other main surfaces of the socket unit 3, essentially semispherical and forms a fitting surface for load- absorbing support against the concave hollow 35 in the pelvis.
• a trepan 44 is used (see Figs. 6 and 17) to adapt the dimension of the femoral neck 13 so that it affords a positive lock when the ball 5 with its cutting profile is tightened or screwed on. So that both the threaded cylinder wall of the ball and the central shaft are adapted correctly on the one hand to the outer contour of the femoral neck and, on the other hand, to its fixture, the trepan for form adaptation of the femoral neck is fixed with a central guide pin 45 which goes into the fixture which in this respect forms a guide bearing.
• the rotation of the trepan about the guide pin 45 produces a bearing surface, rotationally symmetrical relative to the longitudinal axis of the anchoring element, on the femoral neck whose shape is adapted to the cylindrical inner wall 11 of the joint head.
• the central shaft 14 With both its cylin- drical and threaded part slides into the centre of the cavity in the femoral neck fixture, which cavity con ⁇ stitutes a space for both the pin and also the internally threaded locking sleeve introduced from the other end of the fixture.
• This sleeve is provided with a prestressing device against the fixture so that, when it is threaded against the ball pin, it causes the ball to press against the femoral neck.
• the Jball acquires, on the one hand, a positive locking and, on the other hand, a prestressing against its bone base.
• the titanium socket is fixed in the acetabulum by means of, on the one hand, the central outer pin 37 of the socket, which pin forms a male connection in the female seat of the pelvic fixture, and, on the other hand, screw connections directly to the bone tissue via the holes 41 in the titanium socket.
• the pin on the socket has a conical finish towards its socket attachment with a gradient of 1:15. This compensates for tensile stress at the socket-leg transition, but the primary function of the pin is to neutralize the moment which arises via the various compression screws 40 which risk causing both tensile and shearing stress on the opposite side of the socket-leg connection.
• the titanium socket is thus fitted on a bone surface, well adapted by bone transplantation, by means of, on the one hand, the central conical pin and, on the other hand, three to five compression screws introduced through holes in the titanium socket.
• the joint socket is fitted to the base socket via the snap attachment 33, 34.
• the joint socket which consists for example of high-density polyethylene, is now fixed to the acetabulum via, on the one hand, an osseointegrated anchoring element in the form of a titanium fixture and, on the other hand, the base socket with its compression screws.
• the two operations required for introducing the hip joint replacement should be separated by an interval of at least 3 months.
• the first surgical intervention can be carried out via a small lateral incision, such as is used in nailing of a fracture of the collum, and in this operation, under fluoroscopy and with the patient on one side, a central hole is made in the head of the collum and this hole is extended into the acetabular base of the pelvis.
• the procedure is carried out in a precise manner, as in collum nailing, starting with a Kirschner wire in order to find the ideal position with the aid of TV fluoros- copy, and then a cannulated drill and a cannulated thread tap are used to make a hole through the entire head and the acetabular base with a diameter of about 11 to 12 mm.
• the pelvic fixture which is very short is then introduced by means of a long insertion device through the hole in the collum head, after which the femoral neck fixture is introduced through the same hole up to a level with the cartilage-bone limit on the head.
• the second operation requires considerably greater intervention.
• the approach must be from the front with regard to the anteversion angle of the collum, and the incision and technique are approximately the same as used - 13 -
• a trepan is used to cut the head of the collum, which trepan has been described above and can advantageously be manually operated.
• the trepan has a central pin which is introduced into the femoral neck fixture, and the trepan is guided so as to cut the bone. This can be carried out in several stages if the bone is hard and, in this case, a series of trepans of gradually decreasing diameters is used.
• the hip joint prosthesis in the second embodiment is made up of two joint units here: a first joint unit -45 anchored in the human femoral neck 13 and a second joint unit 46 anchored in the human pelvis 47.
• the joint unit anchored in the femur 2 has a joint head 48 anchored by means of an anchoring arrangement 49 which uses the same anchoring principle as that in the first embodiment, but which in other respects is of a different design.
• the joint head 48 also differs to the extent that there is no cavity for receiving a shaped part of the human femoral neck 13, but has instead an essentially plane bearing surface 50 for bearing against a plane bearing surface 51, made by cutting (see Fig. 24), in the human bone tissue.
• This bearing surface 51 in the bone tissue extends preferably at right angles to the longitudinal axes of the recessed channels 57.
• the anchoring arrange ⁇ ment 49 in the second embodiment does not have only one anchoring element, and one tightening element, but at least two. In the example shown there are three sleeve- shaped anchoring elements 52, 53, 54, and a number of - 14 -
• the sleeve-shaped anchoring elements 52, 53, 54 are each introduced into a respective continuous channel 57 in the femur (see Fig. 23) and have an essentially cylindrical outer circum ⁇ ferential surface 58 which is provided with grooves which, in the example shown, are directed across the longitudinal direction of the anchoring elements and can be elongate linear grooves or, as in the example shown, can form a thread, i.e. extend in a spiral shape.
• the external diameters of the anchoring elements and the diameters of the recessed channels 57 are adapted in such a way that the anchoring elements completely fill the width of the channels and engage with the grooves in the bone tissue.
• the anchoring elements 52, 53, 54 have a section 59, directed towards the joint head 48, which does not make bone contact and expediently has a smooth cylindrical circumferential surface.
• the anchoring elements fill the entire length of the recessed channels 57 up to the bearing surface 51 of the femoral neck.
• the anchoring elements 52 - 54 thus preferably extend at ' right angles to the bearing surface 50 of the joint head 48.
• Fig. 21 shows the mutual positions and extents of the anchoring elements. It also shows that one anchoring element 52 expediently has a greater external and inter ⁇ nal diameter than the two other anchoring elements 53, 54 and that the anchoring elements have a mutual posi- tioning, viewed from their end, in which their mutually parallel longitudinal axes form, in a plane transverse thereto, the corners of an isosceles triangle with the larger anchoring element 52 positioned distal at the apex of the isosceles triangle, while the two smaller ancho- ring elements are positioned proximal and each form a corner of the triangle base, which is the shortest side of the triangle.
• the anchoring elements 52 - 54 are suitably made of a strong and tissue-compatible material. - 15 -
• Fig. 20 shows that the joint head 48 has a number of essentially cylindrical flanges 60 projecting from the bearing surface 50 of the head, the . number thereof corresponding to the number of anchoring elements.
• the flanges 60 extend rotationally symmetrical about the common longitudinal axes of the anchoring elements and tightening elements in their assembled state.
• three cylindrical flanges 60, 61 projecting from the bearing surface 50 of the joint head 48 are designed as integrated parts in the bearing surface of the joint head.
• the flanges 60, 61 have a cylindrical internal surface 62 for guiding and bearing against the external circumferential surface 58 of the associated anchoring element, more specifically at its
• each flange also has an outer, essentially cylindrical or, for example, conical bearing surface 63 which is rotationally symmetrical about the anchoring element and tightening element and which is intended to bear against a recessed bearing surface 64 in the femoral neck.
• This bearing surface 64 is thus rotationally symmetrical about the associated recessed channel 57 in the femoral neck and forms a widened part of this at the end of the channel towards the joint head 48. The procedure for making this recess is explained in greater detail below with reference to Fig. 24.
• the joint head also has a recess 65 for each tightening element 55, which recess 65 is shaped after the form of the end 66 of the tightening element and is, for example, essentially cylindrical and is either provided beforehand with internal threads or is formed for thread engagement with the end part of the tightening element, which end - 16 -
• each of the three projecting bearing flanges 60, 61 are rotationally symmetrically arranged with an axis of symmetry which coincides with the axis of symmetry of the recesses 65.
• the recesses 65 are expediently dimensioned with such a depth that the tightening elements 55 do not reach the bottom of the recesses, but rather there is a certain amount of space for necessary tolerances and also for prestressing of the joint head 48 against the bearing surface 51 of the femoral neck.
• the load-absorbing surfaces consist essentially of the annular end surfaces 67 of the tightening elements, against which end surfaces there bear corresponding surfaces 68 in the bottom of the cavity 69 designed as a hollow cylinder, except for the force absorption which is effected in the screw connection between the end 66 of the tightening element and the recess 65 in the joint head 48.
• the joint head 48 rests and is thus anchored in three take- up positions, which affords a stable force absorption as regards both tensile, bending and torsional forces.
• This step-like surface 70 corresponds to the end surface 71 of each flange 60, which does not necessarily need to reach the bottom of the recess, but rather a space can exist for tolerances and prestressing. Thus, no forces are to be transmitted between these two surfaces 70, 71.
• the tightening elements 55 are designed as screws which, however, only have to be threaded in their part situated outside the sleeve-shaped anchoring element.
• the main part 72 of the tightening element extends in the con ⁇ tinuous and expediently cylindrical channel 73 formed by means of the sleeve shape of the anchoring element, with - 17 -
• the cylindrical part 72 of the tighte ⁇ ning element in the channel is expediently smooth and dimensioned for good fitting in the anchoring element with small tolerances, so that the tightening element can, during assembly, be introduced into the anchoring sleeve with satisfactory guiding therein.
• Each of the tightening elements moreover has a head 75 which is expediently recessed in a conical countersink 76 in that end of the anchoring element distant from the joint head 48.
• a groove is arranged, for example for a hexagonal wrench.
• a flange 77 common to all three anchoring elements is connected firmly to the ends of the anchoring elements by means of these being threaded into holes in the flange.
• the flange 77 is shaped in such a way that it matches as well as possible the form of the femur 2.
• An important factor for the main parts of the anchoring arrangement, namely the anchoring elements and tightening elements, is that the anchoring elements should have such an extension and also be arranged in such a way that direct contact between tightening element and bone tissue is' avoided, which is a precondition for implantation in two separate sequences. In the example shown in Fig. 20, the tightening elements are completely isolated from direct contact with bone tissue, and the anchoring is effected entirely via the anchoring elements.
• the joint head 48 and the other joint unit 46 which is a joint socket unit, can be designed in different ways.
• the joint head 48 is designed as an expediently solid partial sphere with a spherical surface 78.
• the joint head 48 is made, for example, of a strong and tissue-compatible material, such as titanium.
• the joint socket unit has a socket 79 which is likewise expediently made of titanium and which, by means of an anchoring arrangement 80, is anchored in the - 18 -
• anchoring elements 81 designed as sleeve-shaped elements, which are likewise expediently made of titanium and are introduced into previously formed channels in the hip bone. Grooves in the circumferential surface 82 ensure a secure engage ⁇ ment and osseointegration in the bone tissue.
• the anchoring elements are designed in such a way that direct contact is avoided between tightening elements 83 in the fcrm of screws, which are introduced into the anchoring elements in a later operation sequence and screwed into the threaded cavity 84 of the anchoring elements.
• the screws 83 have heads 85 which are recessed in countersinks 86 in the socket 79 in such a way that they do not cross the concave surface 87 of the socket, which is made, for example, with a polymer lining or as a separate socket part secured in the joint socket in order to provide a good bearing against the joint head.
• Implantation of the hip joint prosthesis shown in Fig. 20 is carried out in a way which shows similarities to the procedure in connection with implantation of the first embodiment.
• a drill guide (not shown) is introduced under TV fluoroscopy through the upper part of the side of the femur, up through the lower part of the femoral neck and penetrating the joint head in a direction indicated by the dot-and-dash line 89 in Fig. 22.
• the first of the channels described above in the femur 2 is then made by guiding a drill guide. Thereafter, the two other channels are made in a cutting direction indicated by the arrows 90, 91, i.e. parallel to the direction of the first channel.
• the hip With continued TV fluoroscopy, the hip is put into a position in which the first drilled channel points centrally up into the pelvis 47.
• a hole is drilled and threaded into the acetabulum 92, i.e. into the pelvis.
• One of the anchoring elements 81 for the socket unit 46 is then threaded into the acetabulum.
• channels are made in the acetabulum for other anchoring elements by suitable adjustment and - 19 -
• the channels are threaded and the three anchoring elements 52, 53, 54 are introduced into the associated channels. Thereafter, the first operation sequence is finished, and the implant is allowed to set.
• the second operation sequence is initiated by opening and exposing the hip joint, after which the femoral neck is sawn off at the level of the previously introduced anchoring elements 52, 53, 54, as shown in Fig. 24. This affords the plane bearing surface 51 of bone tissue in the femoral neck.
• a cutting instrument 93 in the form of a so-called trepan is then used to cut the bone tissue in order to shape the reces- ses which are intended to take up the collar-like flanges
• the cutting instrument more specifically their continuous cylindrical channel 73, form an axle guide for the cutting tool.
• the latter is in fact designed with, in addition to a drive shaft 94 connected to a drive motor, a forward extension in the form of a guide axle 95 which expediently is essentially cylindrical and has a diameter which, with suitable tolerance, corresponds to the internal diameter of the anchoring elements.
• the cutting instrument moreover has a circular saw 96 which is arranged rota ⁇ tionally symmetrical about the guide axle 95, produces a cylindrical cutting and is dimensioned in such a way that the recess in the bone tissue takes up the collar-like flanges 60 with good fitting.
• two different dimensions of the cutting instrument are thus required for matching with the two different dimensions of the anchoring elements and flanges.
• the cutting instrument is advantageously adapted so that a desired depth has been achieved when the instrument reaches the end surfaces 67 of the anchoring elements.
• the socket unit 46 is then secured in its anchoring elements 81 by means of tightening elements 83. It should be ensured that the bearing surface 51 of the femoral neck is carefully adapted to the end surfaces 67 of the anchoring elements, in which respect, for example, the bearing surface 51 can be situated slightly in front of the bearing surfaces 67 so that a certain prestressing can be achieved.
• the joint head 48 is then secured on the femoral neck by means of the flanges 60 being intro- quizd into their recesses and the tightening elements 55 being introduced into the anchoring elements and their ends screwed into the joint head until the end surfaces 67 of the anchoring elements reach the surfaces 68 of the joint head.
• the plane bearing surface 50 of the joint head 48 is advantageously pressed against the plane, cut bearing surface 51 of the femoral neck with a certain prestressing.
• the hip joint is then reset and the wound is closed, after which the operation is complete.
• Fig. 25 shows an example of a further embodiment in which the joint head, here designated by 97, has another shape with a more pronounced ball 98 and a neck part 99. Otherwise, the prosthesis is anchored in the femur in the same way as in the embodiment described above.
• the socket unit, here designated by 100 is divided into two sections: on the one hand a base socket 101, which is anchored in the manner described above for the second embodiment, and an inner socket 102, which can be made of a wear-resistant low-friction material.
• the inner socket 102 is, for example, secured in the base socket by means of a snap lock 103, locking ring or the like.
• the embodiment shown in Fig. 26 has a joint head, here designated by 104, of a completely different type.
• the joint head is designed as a ball bearing 105, mounted around an axle 106 formed in the joint head, which thus - 21 -
• the joint socket is provided with an annular element 110 which gives the socket a spherical surface, which exceeds a semisphere, by which means the joint head in the form of the ball bearing 105 cannot be removed from its articulating connection with the socket unit.
• the prestressable anchoring arrangement for the joint head can have another detail design.
• the pin 14 can have a length which corresponds essentially to the length of the anchoring element 6 so that the screw 7 projects, in the assembled state, slightly outside the flange 20 of the anchoring element and is prestressed with a nut instead of the screw bushing 8.
• the nut can be expediently countersunk or encapsulated.
• the screw 7 can be replaced by a. sleeve which forms the pin 14 and has a bore with an internal thread, in which connection the screw bushing 8 is replaced by a screw.
• the socket unit can have a completely different design from the unit shown.
• the joint head and its surfaces bearing against the bone tissue can also be designed in several different ways.
• a non-plane bearing surface between the joint head and femoral neck is also conceivable in an embodiment with three anchoring elements. Even if the anchoring arrange ⁇ ment is prestressable, it is not necessary per se to use the prestressing possibility in each application.
• the expression "grooved outer surface” also includes "threa ⁇ ded outer surface” . In the embodiment with three ancho- r i ng elements it is not necessary to choose the con ⁇ figuration of an isosceles triangle, and another triangle with different sides is conceivable.

Landscapes

• Health & Medical Sciences (AREA)
• Orthopedic Medicine & Surgery (AREA)
• Cardiology (AREA)
• Oral & Maxillofacial Surgery (AREA)
• Transplantation (AREA)
• Engineering & Computer Science (AREA)
• Biomedical Technology (AREA)
• Heart & Thoracic Surgery (AREA)
• Vascular Medicine (AREA)
• Life Sciences & Earth Sciences (AREA)
• Animal Behavior & Ethology (AREA)
• General Health & Medical Sciences (AREA)
• Public Health (AREA)
• Veterinary Medicine (AREA)
• Prostheses (AREA)
• Preparation Of Compounds By Using Micro-Organisms (AREA)
• Peptides Or Proteins (AREA)
• Medicines Containing Material From Animals Or Micro-Organisms (AREA)

Priority Applications (2)

Applications Claiming Priority (2)

Publications (1)

Family

ID=20372596

Family Applications (1)

Country Status (6)

Cited By (36)

Families Citing this family (11)

Citations (4)

• 1988
  • 1988-06-10 SE SE8802194A patent/SE463072B/sv not_active IP Right Cessation
• 1989
  • 1989-06-12 AT AT89906842T patent/ATE112953T1/de not_active IP Right Cessation
  • 1989-06-12 DE DE68918939T patent/DE68918939T2/de not_active Expired - Fee Related
  • 1989-06-12 WO PCT/SE1989/000329 patent/WO1989011837A1/en active IP Right Grant
  • 1989-06-12 JP JP1506230A patent/JPH03504932A/ja active Pending
  • 1989-06-12 EP EP89906842A patent/EP0418301B1/en not_active Expired - Lifetime

Patent Citations (4)

Also Published As

Similar Documents

Legal Events