Hip prosthesis with monoblock ceramic acetabular cup

• US 7,695,521 B2
• Filed: 08/12/2005
• Issued: 04/13/2010
• Est. Priority Date: 05/01/2001
• Status: Expired due to Fees

• Current Assignee: Amedica Corporation
• Original Assignee: Amedica Corporation
• Inventors: Ely, K. Scott, Khandkar, Ashok C., Lakshminarayanan, Ramaswamy, Hofmann, Aaron A.
• Primary Examiner(s): Matthews; William H.
• Assistant Examiner(s): STROUD, JONATHAN R
• Application Number:
  US11/203,047
• Publication Number:
  US 20050273176A1
• Time in Patent Office: 1,705 Days
• Field of Search: 623/22.11, 623/22.15, 623/22.18, 623/22.21, 623/22.17, 623/22.24, 623/22.28, 623/22.32, 623/22.38
• US Class Current: 623/22.21
• CPC Class Codes: A61F 2/30767 Special external or bone-contacting surface, e.g. coating for improving bone ingrowth
• CPC Class Codes: A61F 2/32 for the hip
• CPC Class Codes: A61F 2/34 Acetabular cups
• CPC Class Codes: A61F 2/36 Femoral heads ; Femoral endoprostheses
• CPC Class Codes: A61F 2/3662 Femoral shafts
• CPC Class Codes: A61F 2002/30011 differing in porosity
• CPC Class Codes: A61F 2002/30324 differing in thickness
• CPC Class Codes: A61F 2002/30332 Conically- or frustoconically-shaped protrusion and recess
• CPC Class Codes: A61F 2002/30685 Means for reducing or preventing the generation of wear particulates
• CPC Class Codes: A61F 2002/30934 Special articulating surfaces
• CPC Class Codes: A61F 2002/349 Shell having a wavy or undulated peripheral rim
• CPC Class Codes: A61F 2002/3611 Heads or epiphyseal parts of femur
• CPC Class Codes: A61F 2002/3625 Necks
• CPC Class Codes: A61F 2002/365 Connections of heads to necks
• CPC Class Codes: A61F 2220/0033 made by longitudinally pushing a protrusion into a complementary-shaped recess, e.g. held by friction fit
• CPC Class Codes: A61F 2250/0023 differing in porosity
• CPC Class Codes: A61F 2250/0036 differing in thickness
• CPC Class Codes: A61F 2310/00011 Metals or alloys
• CPC Class Codes: A61F 2310/00029 Cobalt-based alloys, e.g. Co-Cr alloys or Vitallium
• CPC Class Codes: A61F 2310/00179 Ceramics or ceramic-like structures
• CPC Class Codes: A61F 2310/00203 : containing alumina or aluminium oxide
• CPC Class Codes: A61F 2310/00239 : containing zirconia or zirconium oxide ZrO2
• CPC Class Codes: A61F 2310/00317 : containing silicon nitride
• CPC Class Codes: A61L 27/10 : Ceramics or glasses

Abstract

An improved hip prosthesis includes an acetabular cup bearing component constructed from a relatively hard and high strength ceramic material for articulation with a ball-shaped femoral head component which may be constructed from a compatible ceramic or metal material. In one form, the acetabular cup further includes a ceramic porous bone ingrowth surface adhered thereto for secure ingrowth attachment to natural patient bone.

Claims

1. A hip joint prosthesis, comprising:

a monolithic acetabular cup defining a convex upper side having a size and shape adapted for seated engagement within a patient'"'"'s natural acetabulum, and a lower side defining a downwardly open and generally part-spherical cavity lined by an articulation surface having a size and shape for articulatory reception of a matingly shaped femoral component;

said acetabular cup defining a relatively low porosity first region defining said articulation surface, and a comparatively higher porosity second region defining a bone ingrowth surface on said convex upper side thereof, wherein both of said first region and said second region comprise doped silicon nitride ceramic;

said doped silicon nitride ceramic of said relatively low porosity first region having a flexural strength greater than about 700 Mega-Pascal (MPa) and a fracture toughness greater than about 7 Mega-Pascal root meter (MPam^0.5).

2. The hip joint prosthesis of claim 1 wherein said ceramic of said comparatively higher porosity second region has pores formed therein with a pore size ranging from about 100 microns to about 500 microns.

3. The hip joint prosthesis of claim 1 further comprising said matingly shaped femoral component wherein said matingly shaped femoral component comprises a ball-shaped femoral head.

4. The hip joint prosthesis of claim 3 wherein said femoral head is formed from a ceramic material.

5. The hip joint prosthesis of claim 3 wherein said femoral head is formed from a ceramic material substantially identical to the acetabular cup ceramic material.

6. The hip joint prosthesis of claim 3 wherein said femoral head is formed from a biocompatible metal.

10. The hip joint prosthesis of claim 1 wherein said relatively high porosity second region has greater than 50% porosity to about 80% porosity.

11. The hip joint prosthesis of claim 1 wherein said ceramic of said relatively low porosity first region has a flexural strength greater than about 800 Mega-Pascal (MPa) and a fracture toughness greater than about 9 Mega-Pascal root meter (MPam^0.5).

7. A hip joint prosthesis, comprising:

a monolithic acetabular cup defining a convex upper side and having a size and shape adapted for seated engagement within a patient'"'"'s natural acetabulum, and a lower side defining a downwardly open and generally part-spherical cavity lined by an articulation surface having a size and shape for articulatory reception of a matingly shaped femoral component;

said acetabular cup being formed from a doped silicon nitride ceramic material having a flexural strength greater than about 700 Mega-Pascal (MPa) and a fracture toughness greater than about 7 Mega-Pascal root meter (MPam^0.5); and

said acetabular cup having a rim defined by the circumferential free edge between said upper and lower sides, and wherein said rim includes a pair of generally identically-shaped and diametrically opposed recesses formed therein for increased range of motion, wherein each recess extends from said upper side to said lower side.

8. The hip joint prosthesis of claim 7 wherein said pair of generally identically-shaped and diametrically opposed recesses formed in said rim provides increased range of motion in a flexion/extension plane.

9. The hip joint prosthesis of claim 7 wherein said ceramic material has a flexural strength greater than about 800 Mega-Pascal (MPa) and a fracture toughness greater than about 9 Mega-Pascal root meter (MPam^0.5).