Femoral prosthesis

• US 5,571,204 A
• Filed: 07/13/1995
• Issued: 11/05/1996
• Est. Priority Date: 07/14/1994
• Status: Expired due to Fees

• Current Assignee: Berthold Nies
• Original Assignee: Merck Patent GmbH (Merck & Co., Inc.)
• Inventors: Nies, Berthold
• Primary Examiner(s): Milano, Michael J.
• Application Number:
  US08/501,923
• Time in Patent Office: 481 Days
• Field of Search: 623/22, 623/23
• US Class Current: 623/23.19
• CPC Class Codes: A61B 17/7098 wherein the implant is permeable or has openings, e.g. fenestrated screw hollow surgical screws A61B17/864
• CPC Class Codes: A61B 17/8802 Equipment for handling bone cement or other fluid fillers
• CPC Class Codes: A61F 2/30723 Plugs or restrictors for sealing a cement-receiving space tools for inserting plugs A61F2/4614; sealing collars for use during cementing A61B17/8808
• CPC Class Codes: A61F 2/30724 Spacers for centering an implant in a bone cavity, e.g. in a cement-receiving cavity
• CPC Class Codes: A61F 2/30907 Nets or sleeves applied to surface of prostheses or in cement
• CPC Class Codes: A61F 2/3662 Femoral shafts
• CPC Class Codes: A61F 2/367 Proximal or metaphyseal parts of shafts trochanteric devices connected to said proximal parts A61F2/30739
• CPC Class Codes: A61F 2/3676 Distal or diaphyseal parts of shafts
• CPC Class Codes: A61F 2002/30062 (bio)absorbable, biodegradable, bioerodable, (bio)resorbable, resorptive
• CPC Class Codes: A61F 2002/30563 having elastic means or damping means, different from springs, e.g. including an elastomeric core or shock absorbers
• CPC Class Codes: A61F 2002/30583 filled with hardenable fluid, e.g. curable in-situ
• CPC Class Codes: A61F 2002/30677 Means for introducing or releasing pharmaceutical products, e.g. antibiotics, into the body
• CPC Class Codes: A61F 2002/30917 for avoiding direct contact between bone and implant, e.g. extensible membrane for preventing contamination or for easy removal
• CPC Class Codes: A61F 2002/3694 with longitudinal bores
• CPC Class Codes: A61F 2002/4631 the prosthesis being specially adapted for being cemented
• CPC Class Codes: A61F 2210/0004 bioabsorbable
• CPC Class Codes: A61F 2210/0085 hardenable in situ, e.g. epoxy resins

Abstract

A femoral prosthesis for implantation by cementation, has the stem with a longitudinal borehole extending proximally to distally for the transprosthetic application of the bone cement. The prosthesis stem is surrounded by an elastic sheath of a biocompatible polymeric material in such a way that, on application of the cement, the sheath is filled advancing distally to proximally and, when the space between stem and bone bed is completely filled, pressed flush against the bone bed.

Claims

1. A femoral prosthesis (1) for implantation by cementation in a bone bed (6), the prosthesis having a prosthesis stem (2) thereof with a longitudinal borehole (3) extending from a proximate end to a distal end for transprosthetic application of bone cement, the improvement comprising:

spaces (7) for centering and aligning the prosthesis in the proximal region;

a medullary space blocker (8) for fastening the sheath (4) in the distal region;

an elastic sheath (4) of a biocompatible polymeric material, the sheath (4) having pores therein and surrounding the prosthesis stem in such a way that, on application of the cement through the bore hole, the sheath is filled starting at the distal end and advancing to the proximate end of the prosthesis, wherein when a space (5) between stem (2) and the bone bed (6) is completely filled, the elastic sheath (4) is pressed flush against the bone bed (6) and the pores widen so that the bone cement comes into contact with the bone bed (6).

2. The femoral prosthesis according to claim 1, wherein the sheath (4) is comprised of a bioabsorbable polymeric material.

3. The femoral prosthesis according to claim 2, wherein the sheath (4) is comprised of a bioabsorbable polymeric material containing osteoinductive and osteoconductive fillers.

4. The femoral prosthesis according to claim 3, wherein the sheath (4) is impregnated with agents which are selected from the group consisting of antibiotics and bone growth promoters.

5. A femoral prosthesis (1) for implantation by cementation in a bone bed (6), the prosthesis having the prosthesis stem (2) thereof with a longitudinal borehole (3) extending from a proximate end to a distal end for transprosthetic application of bone cement, the improvement comprising:

an elastic sheath (4) of a biocompatible polymeric material, the sheath (4) having pores therein and surrounding the prosthesis stem in such a way that, on application of the cement through the bore hole, the sheath is filled starting at the distal end and advancing to the proximate end of the prosthesis, wherein when a space (5) between stem (2) and the bone bed (6) is completely filled, the elastic sheath (4) is pressed flush against the bone bed (6) and the pores widen so that the bore cement comes into contact with the bone bed (6).

6. The femoral prosthesis according to claim 5, wherein the sheath (4) is fastened in the distal region to a medullary space blocker (8).

7. The femoral prosthesis according to claim 5, wherein the sheath (4) is comprised of a bioabsorbable polymeric material.

8. The femoral prosthesis according to claim 5, wherein the sheath (4) is comprised of a polymeric material selected of the group consisting of osteoinductive and osteoconductive fillers.

9. The femoral prosthesis according to claim 5, wherein the sheath (4) is impregnated with agents which are selected from the group consisting of antibiotics and bone growth promoters.

10. An implantation kit for implanting a prosthesis in a bone bed comprising:

(a) a bone cement which is ready for use and is prepared for application;

(b) a femoral prosthesis for implantation by cementation, wherein the prosthesis stem has a selected shape and a longitudinal borehole extending from a proximate end to a distal end for the transprosthetic application of the bone cement; and

(c) a sheath comprising an elastic biocompatible polymeric material, which sheath is adapted in initial shape and dimensions to conform to the shape of the prosthesis stem, the sheath having pores which widen as the sheath is filed with bone cement introduced into the longitudinal bore hole of the prosthesis stem to expand the sheath outwardly to conform in shape and size to the inner surface of the bone bed.

11. The implantation kit according to claim 10, wherein medullary space blocker with, where appropriate, a centering device for the prosthesis is attached at the distal end of the sheath.