CH660681A5 - Femoral head prosthesis - Google Patents
Femoral head prosthesis Download PDFInfo
- Publication number
- CH660681A5 CH660681A5 CH4941/85A CH494185A CH660681A5 CH 660681 A5 CH660681 A5 CH 660681A5 CH 4941/85 A CH4941/85 A CH 4941/85A CH 494185 A CH494185 A CH 494185A CH 660681 A5 CH660681 A5 CH 660681A5
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- CH
- Switzerland
- Prior art keywords
- head
- joint head
- extension
- conical
- plug
- Prior art date
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Classifications
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- 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
- A61F2002/30331—Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements made by longitudinally pushing a protrusion into a complementarily-shaped recess, e.g. held by friction fit
- A61F2002/30354—Cylindrically-shaped protrusion and recess, e.g. cylinder of circular basis
-
- 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
- A61F2002/30535—Special structural features of bone or joint prostheses not otherwise provided for
- A61F2002/30593—Special structural features of bone or joint prostheses not otherwise provided for hollow
-
- 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
- A61F2002/30667—Features concerning an interaction with the environment or a particular use of the prosthesis
- A61F2002/30673—Lubricating means, e.g. synovial pocket
-
- 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
- A61F2002/3611—Heads or epiphyseal parts of femur
- A61F2002/3621—Heads or epiphyseal parts of femur pierced with a longitudinal bore
-
- 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
- A61F2002/3625—Necks
-
- 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
- A61F2002/365—Connections of heads to necks
-
- 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
- A61F2220/0033—Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements made by longitudinally pushing a protrusion into a complementary-shaped recess, e.g. held by friction fit
-
- 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
- A61F2310/00179—Ceramics or ceramic-like structures
- A61F2310/00185—Ceramics or ceramic-like structures based on metal oxides
- A61F2310/00203—Ceramics or ceramic-like structures based on metal oxides containing alumina or aluminium oxide
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)
Abstract
The ceramic articular head (1) of a femoral head prosthesis is fixed on a metallic push-on part (3) in which a hollow cylindrical, stem-like extension (2) of the articular head (1) sits tightly on a cylindrical push-on part (3). The outer jacket of the extension (2) is conically widened toward the apex of the articular head (1) and inserted in a groove (7) which also widens conically toward the apex of the articular head (1). The groove (7) is formed by a collar (8) which surrounds the push-on part (3) annularly on the outside. In the novel conical push-on connection the articular head (1) is exposed only to pressure and no longer to traction. <IMAGE>
Description
**WARNUNG** Anfang DESC Feld konnte Ende CLMS uberlappen **.
PATENTANSPRÜCHE 1. Femurkopfprothese mit einer konischen Steckverbindung zwischen einem hohlen keramischen Gelenkkopf und einem erhabenen metallischen Aufsteckteil, auf den der Gelenkkopf aufgesteckt ist, dadurch gekennzeichnet, dass eine hohlzylindrische stammartige Verlängerung (2) des Gelenkkopfes (1) im kreiszylindrischen Pass-Sitz auf dem Aufsteckteil (3) sitzt, dass ferner der Aussenmantel der Verlängerung (2) sich gegen den Gelenkkopf(l) konisch erweitert, und dass schliesslich die konische Erweiterung in einer sich ebenfalls gegen den Gelenkkopf (1) konisch öffnenden, den Aufsteckteil (3) aussen umschliessenden Rinne (7) abgestützt ist.
2. Femurkopfprothese nach Anspruch 1, dadurch gekennzeichnet, dass die Rinne (7) durch einen separaten, auf den Aufsteckteil (3) aufgesteckten Kragen (8) gebildet ist.
3. Femurkopfprothese nach Anspruch 1, dadurch gekennzeichnet, dass zwischen der konischen Fläche des Aussenmantels (2) und derjenigen der Rinne (7) ebenfalls ein Pass-Sitz besteht.
4. Femurkopfprothese nach Anspruch 1, dadurch gekennzeichnet, dass die konische Steckverbindung zwischen der stammartigen Verlängerung (2) und der Rinne (7) selbsthemmend ausgebildet ist.
Die Erfindung betrifft eine Femurkopfprothese mit einer konischen Steckverbindung zwischen einem hohlen keramischen Gelenkkopf und einem erhabenen metallischen Aufsteckteil, auf den der Gelenkkopf aufgesteckt ist.
Es ist bekannt, bei einer Femurkopfprothese der genannten Art mit ihrer Verbundkonstruktion aus zwei, in ihren Eigenschaften sehr verschiedenen Materialien die beiden Prothesenteile über eine konische Steckverbindung selbsthemmend miteinander zu verbinden (CH-PS 603 149). Um die Belastungen des aus einem der üblichen biokeramischen Werkstoffe bestehenden spröden Gelenkkopfes durch Zug/ Biegekräfte, die zu einem Reissen und Springen des Kopfes führen können, zu erniedrigen, hat man beide Prothesenteile mit unterschiedlichen Konuswinkeln versehen und den Verformungswiderstand der Oberfläche des erhabenen Metallteils künstlich erniedrigt (CH-PS 598 806). Die Praxis hat gezeigt, dass in bestimmten Fällen die Gefahr einer Zerstörung der Keramikkugel bei extremen Belastungen mit den geschilderten Massnahmen nicht vollständig gebannt werden kann.
Beispielsweise ist bei sogenannten Rotationsprothesen die Wandstärke des keramischen Gelenkkopfes verringert, da dieser zunächst über die konische Steckverbindung auf einer metallischen Zwischenhülse sitzt, die ihrerseits auf einem metallischen Zapfen rotieren kann (CH-PS 593 053); auch mit den erwähnten Massnahmen zur Verringerung der Belastungen des Keramikkopfes ergeben sich bei den relativ geringen Wandstärken unter Umständen Schwierigkeiten.
Aufgabe der Erfindung ist es, eine konische Steckverbindung zwischen einem keramischen Gelenkkopf und einem metallenen Aufsteckteil zu schaffen, bei der der Gelenkkopf nach Möglichkeit nur Druckbelastungen ausgesetzt ist, gegen die spröde Keramikteile bekanntlich wesentlich widerstandsfähiger sind als gegen Zugbelastungen.
Diese Aufgabe wird mit der Erfindung dadurch gelöst, dass eine hohlzylindrische stammartige Verlängerung des Gelenkkopfes im kreiszylindrischen Pass-Sitz auf dem Aufsteckteil sitzt, dass ferner der Aussenmantel der Verlängerung sich gegen den Gelenkkopf konisch erweitert, und dass schliesslich die konische Erweiterung in einer sich ebenfalls gegen den Gelenkkopf konisch öffnenden, den Aufsteckteil aussen umschliessenden Rinne abgestützt ist.
Die konische Abstützung in der den Aufsteckteil umfassenden Rinne bewirkt, dass auch bei einem Setzen des Gelenkkopfes undloder bei stossartigen Belastungen keine Zugbeanspruchungen des Gelenkkopfes auftreten und nur Druckkräfte auf den keramischen Teil wirken.
Vorteilhafterweise kann die konische Steckverbindung zwischen stammartiger Verlängerung und Rinne selbsthemmend ausgebildet sein undloder ebenfalls in einem Pass-Sitz bestehen. Aus fabrikatorischen Gründen - beispielsweise wegen der Genauigkeit der beiden Pass-Sitze - ist es zweckmässig, wenn die Rinne durch einen separaten, auf den Aufsteckteil aufgesteckten Kragen gebildet ist. Das hat den zusätzlichen Vorteil, dass für Kragen und Aufsteckteil gegebenenfalls unterschiedliche Metalle oder Metall-Legierungen verwendet werden können, falls dies wegen spezifisch verschiedener Anforderungen an den Aufsteckteil und an den Kragen oder aus wirtschaftlichen Gründen wünschenswert ist.
Im folgenden wird die Erfindung anhand eines Ausführungsbeispiels im Zusammenhang mit der Zeichnung näher erläutert.
Die einzige Figur zeigt einen Längsschnitt durch einen Gelenkkopf, der auf einen Aufsteckteil aufgesteckt ist.
Der aus einer der bekannten biokeramischen Werkstoffen, insbesondere aus Al203, gefertigte Gelenkkopf 1 besteht aus einer etwa halbkugelförmigen hohlen Schale, an deren Äquator eine hohlzylindrisch ausgebildete, stammartige Verlängerung 2 angesetzt ist. Der Hohlzylinder der Verlängerung 2, der in den Hohlraum der halbkugelförmigen Schale des Gelenkkopfes 1 übergeht, dient zur Aufnahme eines Aufsteckteils 3, der im vorliegenden Ausführungsbeispiel eines für eine Rotationsprothese bestimmten Gelenkkopfes 1 eine Hülse ist.
In ihrem Zylinderraum 4 nimmt die Hülse 3 einen Zapfen eines nicht gezeigten Schaftteiles auf der Zapfen dient dabei in bekannter Weise einerseits als Gleitlager für Rotationen des Gelenkkopfes 1 und andererseits bei Beund Entlastungen als Kolbenpumpe für das Ansaugen von Körperflüssigkeiten, die als Schmiermittel in dem zwischen Zapfen und Hülse 3 gebildeten Gleitlager dienen, für den Eintritt von Körperflüssigkeit in den Zylinderraum der Kolbenpumpe dienen Bohrungen 5 und 6 im Gelenkkopf 1 bzw. in der Hülse 3.
Der Aussenmantel der stammartigen Verlängerung 2 bildet einen sich zum Kopf 1 hin erweiternden Konus; die Verlängerung 2 sitzt in einer Rinne 7, die zwischen der Hülse 3 und einem Kragen 8 gebildet ist und sich zum Kopf 1 hin ebenfalls konisch erweitert.
Der Kragen 8 besteht, vor allem aus fabrikatorischen Gründen, aus einem separaten ringförmigen Element, das über den Gelenkkopf 1 auf die Hülse 3 aufgesteckt ist und sich an einem stufenförmigen Absatz 9 der Hülse 3 abstützt.
Sowohl der zylindrische Sitz zwischen der Hülse 3 und dem Innenzylinder der stammartigen Verlängerung 2 als auch der konische Sitz zwischen dem Kragen 8 und dem Aussenmantel der Verlängerung 2 sind als Pass-Sitze ausgebildet. Dabei weist der Konus mit Vorteil einen derartigen Öffnungswinkel auf, dass er selbsthemmend wirkt, d. h. der Öffnungswinkel beträgt z. B. 20 53'. Weiterhin sind die Wanddicke der Verlängerung 2 und die Rinnenbreite sowie -tiefe derart aufeinander abgestimmt, dass die Verlängerung 2 mit ihrer Stirnseite in der Rinne 7 Spiel hat, so dass ein Setzen des Gelenkkopfes auf der Hülse 3 möglich ist.
** WARNING ** beginning of DESC field could overlap end of CLMS **.
PATENT CLAIMS 1. Femoral head prosthesis with a conical plug connection between a hollow ceramic joint head and a raised metal plug-on part, on which the joint head is plugged, characterized in that a hollow cylindrical stem-like extension (2) of the joint head (1) in a circular cylindrical fit on the plug-on part (3) that the outer casing of the extension (2) widens conically towards the joint head (l), and that finally the conical enlargement in a conical opening also against the joint head (1) and enclosing the plug-on part (3) on the outside Channel (7) is supported.
2. Femoral head prosthesis according to claim 1, characterized in that the groove (7) is formed by a separate collar (8) which is plugged onto the plug-on part (3).
3. Femoral head prosthesis according to claim 1, characterized in that there is also a snug fit between the conical surface of the outer casing (2) and that of the groove (7).
4. Femoral head prosthesis according to claim 1, characterized in that the conical plug connection between the stem-like extension (2) and the groove (7) is designed to be self-locking.
The invention relates to a femoral head prosthesis with a conical plug connection between a hollow ceramic joint head and a raised metal plug-on part, onto which the joint head is attached.
It is known in a femoral head prosthesis of the type mentioned to connect the two prosthesis parts to one another in a self-locking manner via a conical plug connection (CH-PS 603 149) with its composite construction made of two materials which have very different properties. In order to reduce the loads on the brittle joint head, which consists of one of the usual bioceramic materials, due to tensile / bending forces, which can lead to tearing and cracking of the head, both parts of the prosthesis have been provided with different cone angles and the deformation resistance of the surface of the raised metal part has been artificially reduced (CH-PS 598 806). Practice has shown that in certain cases the risk of destroying the ceramic ball under extreme loads cannot be completely eliminated with the measures described.
For example, in the case of so-called rotary prostheses, the wall thickness of the ceramic joint head is reduced, since it initially sits on a metallic intermediate sleeve via the conical plug connection, which in turn can rotate on a metallic pin (CH-PS 593 053); even with the measures mentioned to reduce the loads on the ceramic head, difficulties may arise with the relatively small wall thicknesses.
The object of the invention is to provide a conical plug connection between a ceramic joint head and a metal plug-on part, in which the joint head is only exposed to pressure loads if possible, against which brittle ceramic parts are known to be substantially more resistant than tensile loads.
This object is achieved with the invention in that a hollow cylindrical stem-like extension of the joint head sits in a circular cylindrical fit on the plug-on part, that the outer jacket of the extension widens conically towards the joint head, and that finally the conical extension also counteracts the articulated head is supported, the gutter enclosing the outer part is supported.
The conical support in the channel comprising the plug-on part ensures that even when the joint head is set and / or in the case of impact loads, no tensile stresses occur on the joint head and only compressive forces act on the ceramic part.
Advantageously, the conical plug connection between the stem-like extension and the channel can be designed to be self-locking and / or can also consist of a snug fit. For manufacturing reasons - for example because of the accuracy of the two fit seats - it is advisable for the gutter to be formed by a separate collar attached to the plug-on part. This has the additional advantage that different metals or metal alloys can optionally be used for the collar and push-on part, if this is desirable because of specifically different requirements for the push-on part and on the collar or for economic reasons.
The invention is explained in more detail below using an exemplary embodiment in conjunction with the drawing.
The single figure shows a longitudinal section through an articulated head which is attached to a plug-on part.
The joint head 1 made of one of the known bioceramic materials, in particular Al203, consists of an approximately hemispherical hollow shell, on the equator of which a hollow cylindrical, stem-like extension 2 is attached. The hollow cylinder of the extension 2, which merges into the cavity of the hemispherical shell of the joint head 1, serves to receive a push-on part 3, which in the present exemplary embodiment of a joint head 1 intended for a rotary prosthesis is a sleeve.
In its cylinder space 4, the sleeve 3 takes a pin of a shaft part, not shown, on the pin serves in a known manner on the one hand as a sliding bearing for rotations of the joint head 1 and on the other hand during loading and unloading as a piston pump for the suction of body fluids that act as lubricants in the between pins and sleeve 3 formed slide bearings, for the entry of body fluid into the cylinder chamber of the piston pump, bores 5 and 6 are used in the joint head 1 and in the sleeve 3rd
The outer jacket of the stem-like extension 2 forms a cone which widens towards the head 1; the extension 2 sits in a groove 7, which is formed between the sleeve 3 and a collar 8 and also widens conically towards the head 1.
The collar 8 consists, mainly for manufacturing reasons, of a separate annular element which is attached to the sleeve 3 via the joint head 1 and is supported on a stepped shoulder 9 of the sleeve 3.
Both the cylindrical seat between the sleeve 3 and the inner cylinder of the stem-like extension 2 as well as the conical seat between the collar 8 and the outer jacket of the extension 2 are designed as fitting seats. The cone advantageously has an opening angle such that it has a self-locking effect, i. H. the opening angle is z. B. 20 53 '. Furthermore, the wall thickness of the extension 2 and the groove width and depth are coordinated with one another in such a way that the end face of the extension 2 has play in the groove 7, so that the joint head can be placed on the sleeve 3.
Claims (4)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
CH4941/85A CH660681A5 (en) | 1985-11-20 | 1985-11-20 | Femoral head prosthesis |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
CH4941/85A CH660681A5 (en) | 1985-11-20 | 1985-11-20 | Femoral head prosthesis |
Publications (1)
Publication Number | Publication Date |
---|---|
CH660681A5 true CH660681A5 (en) | 1987-06-15 |
Family
ID=4285180
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
CH4941/85A CH660681A5 (en) | 1985-11-20 | 1985-11-20 | Femoral head prosthesis |
Country Status (1)
Country | Link |
---|---|
CH (1) | CH660681A5 (en) |
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR2631544A1 (en) * | 1988-05-20 | 1989-11-24 | Cuilleron J | Device for assembling together an element made of ceramic material and a metallic element, in particular for joint prostheses |
US5037441A (en) * | 1989-06-28 | 1991-08-06 | La Biomecanique Integree | Rotule pour prothese |
EP0663194A1 (en) * | 1994-01-17 | 1995-07-19 | Waldemar Link (GmbH & Co.) | Alloplastic bone prosthesis, especially joint endoprosthesis including a conical convection |
US5507830A (en) * | 1989-02-08 | 1996-04-16 | Smith & Nephew Richards Inc. | Modular hip prosthesis |
US5549703A (en) * | 1995-02-16 | 1996-08-27 | Smith & Nephew Richards Inc. | Orthopedic prosthesis apparatus with improved taper locking connection |
-
1985
- 1985-11-20 CH CH4941/85A patent/CH660681A5/en not_active IP Right Cessation
Cited By (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
FR2631544A1 (en) * | 1988-05-20 | 1989-11-24 | Cuilleron J | Device for assembling together an element made of ceramic material and a metallic element, in particular for joint prostheses |
US5507830A (en) * | 1989-02-08 | 1996-04-16 | Smith & Nephew Richards Inc. | Modular hip prosthesis |
US5037441A (en) * | 1989-06-28 | 1991-08-06 | La Biomecanique Integree | Rotule pour prothese |
EP0663194A1 (en) * | 1994-01-17 | 1995-07-19 | Waldemar Link (GmbH & Co.) | Alloplastic bone prosthesis, especially joint endoprosthesis including a conical convection |
US5549703A (en) * | 1995-02-16 | 1996-08-27 | Smith & Nephew Richards Inc. | Orthopedic prosthesis apparatus with improved taper locking connection |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
PL | Patent ceased |