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
  • A61F2/38—Joints for elbows or knees
  • A61F2/3868—Joints for elbows or knees with sliding tibial bearing
• • 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
  • A61F2/38—Joints for elbows or knees
  • A61F2/3836—Special connection between upper and lower leg, e.g. constrained
  • A61F2/384—Special connection between upper and lower leg, e.g. constrained hinged, i.e. with transverse axle restricting the movement
  • A61F2/385—Special connection between upper and lower leg, e.g. constrained hinged, i.e. with transverse axle restricting the movement also provided with condylar bearing surfaces

Definitions

• the invention relates to the technical sector of knee joint prostheses comprising a femoral implant cooperating with a tibial implant.
• the invention finds a particularly advantageous application, in the case of a total knee prosthesis, which comprises a femoral element receiving a transverse articulation axis mounted with free rotation relative to a cylindrical rod, engaged in a sheath integral with the tibial element, as is apparent from the teaching of the patent FR 2,696,927.
• the tibial element comprises a base receiving a polyethylene plate which is mounted with limited rotational displacement capacity in a horizontal plane on said base.
• the tibial plateau receives the femoral element in support with angular flexion capacity.
• the femoral plate is mounted with limited rotational displacement capacity, relative to the sheath secured to the tibial base.
• the tibial plateau which is drilled right through to allow the free engagement of the sheath, has a collar intended to bear on a determined part of the tibial plateau thus ensuring its coupling relative to the tibial base.
• the problem which the invention proposes to solve is to be able to easily and instantaneously couple a tibial plateau relative to a tibial base fitted with a sheath cooperating with the articulation rod of the femoral element, while having the possibility of give the tibial plateau a limited rotational movement relative to said sheath.
• the plate has along its axis of symmetry and from its rear edge, a profiled and shouldered notch delimiting a constricted entry, for, on the one hand being engaged by elasticity around the sheath and, on the other hand, be held in the locked position relative to a flange presented by said sheath, while having a movement of freedom in rotation relative to the sheath, said flange cooperating with a shouldered area formed from the opening of the constricted entrance.
• the shouldered area is formed at a distance from the base of the plate corresponding substantially to the height separating the bearing face of the base from the underside of the flange.
• the shoulder area has, on the side of the opening of the notch, two parallel rectilinear edges which are tangentially connected with an edge semicircular, delimiting a support area for the collar.
• the notch has, on the side of its opening, and in top view, two rectilinear edges oriented in a divergent manner to be connected with two parallel rectilinear segments themselves connected to the bottom of the notch in the form of a semi circular rim which corresponds to the diameter of the sheath and extends beyond a half circumference, to enclose said sheath and create a clipping effect while allowing limited rotation of the plate.
• the inlet of the two divergent straight edges has a width less than the diameter of the sheath to ensure elastic expansion of the bottom of the notch in order to allow the engagement of the sheath under a pressure force.
• FIG. 1 is a perspective view of the tibial implant, before placement of the tray relative to the base.
• FIG. 2 is a longitudinal sectional view of the tibial implant after coupling of the plate on the base.
• FIG. 3 is a sectional view taken along line 3.3 of Figure 2.
• - Figure 4 is a cross-sectional view taken along line 4.4 of Figure 3.
• FIG. 5 is a sectional view of the entire prosthesis.
• the tibial implant finds a particularly advantageous application in the case of a total knee prosthesis, of the type described in patent FR 2696927, of which the applicant for this is also holder.
• the tibial implant comprises a polyethylene plate (1) and a metal base (2).
• the base (2) is equipped with a sheath (3) intended to receive a rod secured to a transverse axis presented by the femoral element.
• the sheath (3) is mounted on the posterior side of the tibial base (2).
• the sleeve (3) is engaged in a well (2a) of the base, being fixed there by any known and appropriate means, in particular by welding.
• the sheath (3) has, at a determined distance (d) from the bearing surface of the tibial base, a bearing and abutment collar (3a).
• the sleeve (3) and the collar (3a) are of circular cross section in order to act as a pivot axis at the tibial plateau (1) by giving it degrees of freedom of rotational movement, in a horizontal plane.
• a profiled notch delimits a constricted entry (lai) in order, on the one hand, to be engaged by elasticity around the sheath (3) and, on the other hand, to be held in the locked position, relative to the flange ( 3 a), while having a movement of freedom in rotation, with respect to said sheath.
• the profiled notch (la) has on the side of its opening (la2), a shouldered zone (la3) for the engagement of the collar (3a) of the sleeve.
• the shoulder area (la3) is formed at a distance (dl) from the base of the plate, corresponding very substantially to the distance (d) separating, as indicated above, the support base from the base (2) from the underside of the collar (3a).
• the shoulder area (la3) has, on the side of the opening (la2) of the notch (la), two parallel straight edges (a) (b) which are tangentially connected with a semi-circular edge (c) delimiting a support area (la4) for the collar (3a).
• the notch (la) has, still on the side of its opening (la2) and in top view, corresponding to the bearing and sliding face of the tibial plateau, two straight edges (d) (e), divergently oriented to connect with two straight segments parallel (f) and (g) themselves connected to the bottom (la5) of the notch in the form of a semi-circular rim which corresponds to the diameter of the sheath and which extends beyond a half circumference.
• the two rectilinear edges (f) and (g) have a width (1) less than the diameter of the sheath (3) to ensure elastic expansion of the bottom (la5) of the notch, in order to allow the engagement of said sheath ( 3) under pressure.
• the bottom (la5) of the groove (la) in which is positioned in support the sheath (3) delimits a semi-circular edge extending beyond a half circumference.
• the engagement of the plate relative to the sheath has the effect, at the time of the introduction, of spreading the notch in order to allow the engagement of said sheath then, after having crossed the zone narrowed (fg), its relaxation by elasticity, in order to close concomitantly on the cross section of said sheath, thus obtaining, in known manner, a clipping effect.

Applications Claiming Priority (3)

Publications (1)

Family

ID=9513906

Family Applications (1)

Country Status (3)

Families Citing this family (5)

Family Cites Families (4)

• 1997
  • 1997-11-24 FR FR9714962A patent/FR2771283B1/fr not_active Expired - Fee Related
• 1998
  • 1998-11-16 EP EP98955659A patent/EP1033948A1/de not_active Withdrawn
  • 1998-11-16 WO PCT/FR1998/002433 patent/WO1999026561A1/fr not_active Application Discontinuation

Non-Patent Citations (1)

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