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
  • A61F2/30988—Other joints not covered by any of the groups A61F2/32 - A61F2/4425
  • A61F2/3099—Other joints not covered by any of the groups A61F2/32 - A61F2/4425 for temporo-mandibular [TM, TMJ] joints
• • 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
  • A61F2002/3011—Cross-sections or two-dimensional shapes
  • A61F2002/30112—Rounded shapes, e.g. with rounded corners
  • A61F2002/30125—Rounded shapes, e.g. with rounded corners elliptical or oval
• • 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
  • A61F2/30721—Accessories
  • A61F2002/30754—Implants for interposition between two natural articular 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
  • A61F2230/00—Geometry of prostheses classified in groups A61F2/00 - A61F2/26 or A61F2/82 or A61F9/00 or A61F11/00 or subgroups thereof
  • A61F2230/0002—Two-dimensional shapes, e.g. cross-sections
  • A61F2230/0004—Rounded shapes, e.g. with rounded corners
  • A61F2230/0008—Rounded shapes, e.g. with rounded corners elliptical or oval

Definitions

• the present invention relates to an endoprosthesis for the joint disc of the temporomandibular joint.
• Endoprostheses for the temporomandibular joint are already known, see DE-PS 21 02 454 and US Pat. No. 3,178,728, which are used when the joint disc of the temporomandibular joint has to be removed due to injury or illness.
• These known endoprostheses are partial endoprostheses that are attached to the zygomatic bone and can be inserted into the socket of the temporomandibular joint with a correspondingly contoured section. Due to the rigid connection to the zygomatic bone, these endoprostheses are not suitable for simulating the joint function of the healthy joint, which is a double joint, with the condyle (joint head) performing a rotational movement and a linear movement.
• the invention has for its object to provide an endoprosthesis for the joint disk of the temporomandibular joint in the event of failure, which largely ensures the natural joint function and which is permanent and the occurrence avoids side effects in the human body.
• the endoprosthesis is formed from a disk-shaped body which is approximately elliptical in outline from a material with a greater surface hardness than that of the bones of the temporomandibular joint, the disk-shaped body being seen in cross-section to its longer axis XX in each case an upper and a has lower concavely curved surface and the radii of curvature of the two surfaces are so different that that the upper surface is larger than that of the lower.
• the invention is based on the knowledge that the shape according to the invention makes it possible to maintain the natural joint function without the need for a muscular connection as with the natural temporomandibular joint.
• the endoprosthesis according to the invention surrounds the condyle in a cap-like manner, with overemphasized enlarged ridges ensuring the functional stability of the artificial disc, so that pathological sliding of the disc cannot occur.
• the design of the artificial disc as a double concave disc, with the concave surfaces having a constant or changing radius of curvature parallel to the smaller axis of the ellipse, is surprising for the person skilled in the art, since this differs fundamentally from the natural design, in which the flexible disc is flexible due to its flexibility has a changing surface shape during the movement of the temporomandibular joint, the shape of which can be described by means of chain line functions. Deviating from this, a constant radius of curvature or changing radius of curvature is provided according to the invention.
• the natural two-chamber joint is changed into a single-chamber joint by the endoprosthesis according to the invention.
• the hardness of the surface of the disc according to the invention is greater than the hardness of the bones of the temporomandibular joint. This ensures permanent function without any adverse side effects, since during the adjustment phase in the joint on the bones of the same (due to necrosis), sharp burrs form which would have a cutting effect on a soft material of the disc. These chips would lead to foreign body granuloma trousers. The invention avoids this danger. Further advantageous embodiments of the invention are contained in the subclaims.
• FIG. 2 is a perspective view of a joint disc according to the invention from the top
• FIG. 3 is a perspective view of a joint disc according to the invention from the bottom view
• FIG. 5 shows a frontal section along the section line VV in FIG. 2.
• a human temporomandibular joint from an articular socket 1 (temporal bone) and a joint head 2 (condyle) of the lower jaw and a joint disc 3 (discus) inserted between them is shown in section according to the invention.
• the precise configuration of the joint disk 3 according to the invention is shown in FIGS. 2 to 5.
• the joint disk 3 has an essentially elliptical circumferential contour, the longer ellipse axis XX in FIG. 1 running perpendicular to the plane of the drawing and the short ellipse axis YY being identified.
• the joint disc 3 consists of a body-compatible material that has a higher surface hardness than the bones of the temporomandibular joint.
• Corrosion-resistant metals and metal alloys such as, for example, titanium and chromium cobalt molybdenum or ceramic materials or metal-ceramic materials are particularly suitable as materials.
• plastics with corresponding properties can also be used.
• the joint disc 3 has two concavely curved surfaces 4 and 5, namely the upper surface 4 facing the joint socket and the surface 5 facing the joint head 2.
• the sagittal radius of curvature of the surface 4 corresponds to the radius of curvature of the os Temporale is designated by r o ⁇ and that of surface 5 corresponding to that of the condyle by r ⁇ .
• the thickness of the joint disk 3 in the area of the minimum disc strength is d.
• r is the radius of curvature of the joint path (axisiography) of the temporomandibular joint.
• the joint disc according to the invention can be determined.
• the therapeutically necessary achsiographic curvature is linked to the coupling formula of the anterior and posterior curvature for a given occlusion, depending on the relationship
• ⁇ is the initial angle of inclination to the functional level and "a" can have an individually constant value from 1 to 6; see also European patent application 861162204.
• ⁇ varies in a frontal direction on the eminentia.
• r ⁇ , r o ⁇ can be determined by computer tomographic recordings.
• d d ( ⁇ ) and must satisfy the above relationship.
• the necessary and therapeutically desired curvature of the joint disc according to the invention must be calculated and produced in every layer depth .
• surface 4 is slightly convexly curved in the direction of the larger axis X-X, while surface 5 is concavely curved in this direction.
• r is the radius of curvature of the axisiography of the temporomandibular joint
• r o ⁇ 1 is the radius of curvature of the temporal bone and the surface 4 facing it
• r ⁇ 1 is the radius of curvature of the condyle and the surface facing it
• d 1 is the thickness of the joint disc on a specific one Point of the joint disc.
• the joint disk according to the invention has an edge bead 6, the outside 7 of which is convexly curved. Due to the fact that the artificial disc is about 1 - 2 mm longer in the frontal and sagittal direction, the edge bead is increased. This relative reinforcement of the edge bead fixes the disc without additional suspension.
• the condyle 2 can, as in the healthy temporomandibular joint, perform a rotational movement around the temporal bone and the condyle.
• the rotational movements take place around the axes RK and ROT.
• the correspondingly assigned articular surface of the temporal bone is surface 4, which is concavely curved with the radius r o ⁇ .
• the movement of the condyle 2 takes place along the temporal bone 1 in the direction of the arrow B.
• the joint disk 3 slides on its surfaces 4 and 5; the surface 5 is also concavely curved, namely with the radius r ⁇ .
• the appropriate joint surface is thus provided for each movement, so that the loads that occur are distributed over two joint surfaces.
• the joint disc 3 lies over the entire surface on the adjacent joint surfaces of the TMJ bones, so that pressure loads are absorbed over the entire surface. Point contacts between the condyle 2 and the temporal bone 1 do not occur.
• the joint disk 3 according to the invention therefore takes on the full function of the natural disc present in the temporomandibular joint.
• the natural disc is held in the joint space, ie in the space between the condyle 2 and the temporal bone 1 by elastic bands and muscles.
• the connection of the joint disc according to the invention to these ligaments and muscles is not necessary, and yet it can sufficiently fulfill the required joint function.
• the joint disc according to the invention is slightly enlarged compared to the natural disc, which also increases the edge bead 6, it is ensured that the condyle 2 does not leave the joint disc during its movements.
• the joint disc according to the invention which rests in a cap-like manner on the condyle, is carried along. This movement of the joint disc corresponds to the natural movement of the disc.
• the synovial disc is completely flushed with synovial fluid, which results in a natural optimal lubrication of the joint and the disc replacement.

Landscapes

• Health & Medical Sciences (AREA)
• Plastic & Reconstructive Surgery (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)

Applications Claiming Priority (2)

Publications (1)

Family

ID=6294736

Family Applications (1)

Country Status (2)

Cited By (6)

Families Citing this family (2)

Citations (6)

• 1986
  • 1986-02-22 DE DE19863605776 patent/DE3605776A1/de active Granted
• 1987
  • 1987-02-19 WO PCT/EP1987/000095 patent/WO1987004917A1/de unknown

Patent Citations (6)

Non-Patent Citations (1)

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