Composite allograft, press, and methods

• US 6,293,971 B1
• Filed: 06/29/1999
• Issued: 09/25/2001
• Est. Priority Date: 03/11/1996
• Status: Expired due to Fees

• Current Assignee: The Board of Trustees of the University of Arkansas (University of Arkansas System)
• Original Assignee: The Board of Trustees of the University of Arkansas (University of Arkansas System)
• Inventors: Hogue, William, Flahiff, Charlene, Nelson, Carl, Hollis, J. Marcus
• Primary Examiner(s): Isabella, David J.
• Application Number:
  US09/343,135
• Time in Patent Office: 819 Days
• Field of Search: 623/16.11, 623/22.15, 623/22.39, 623/23.15, 623/23.28, 623/23.36, 623/23.37, 623/23.5, 623/23.51, 623/23.52, 623/23.56, 623/23.57, 623/23.6, 623/23.61, 623/23.62, 623/23.63, 623/22.21
• US Class Current: 623/23.63
• CPC Class Codes: A61B 17/86 Pins or screws or threaded wires; nuts therefor A61B17/72 take precedence
• CPC Class Codes: A61F 2/28 Bones joints A61F2/30
• CPC Class Codes: A61F 2/3094 Designing or manufacturing processes
• CPC Class Codes: A61F 2/30942 for designing or making customized prostheses, e.g. using templates, CT or NMR scans, finite-element analysis or CAD-CAM techniques
• CPC Class Codes: A61F 2/34 Acetabular cups
• CPC Class Codes: A61F 2002/2835 Bone graft implants for filling a bony defect or an endoprosthesis cavity, e.g. by synthetic material or biological material
• CPC Class Codes: A61F 2002/30787 inclined obliquely with respect to each other
• CPC Class Codes: A61F 2002/30957 using a positive or a negative model, e.g. moulds
• CPC Class Codes: A61F 2002/3401 with radial apertures, e.g. radial bores for receiving fixation screws
• CPC Class Codes: A61F 2002/3429 with an integral peripheral collar or flange, e.g. oriented away from the shell centre line
• CPC Class Codes: A61F 2310/00353 Bone cement, e.g. polymethylmethacrylate or PMMA
• CPC Class Codes: A61F 2310/00359 Bone or bony tissue
• CPC Class Codes: B29C 2043/3639 hand operated
• CPC Class Codes: B29C 43/006 Pressing and sintering powders, granules or fibres
• CPC Class Codes: B29C 43/16 Forging
• CPC Class Codes: B29C 43/36 Moulds for making articles of definite length, i.e. discrete articles
• CPC Class Codes: B29C 43/50 Removing moulded articles
• CPC Class Codes: B29L 2031/3041 Trim panels
• CPC Class Codes: B29L 2031/7532 Artificial members, protheses
• CPC Class Codes: B30B 1/18 by screw means B30B9/3064 takes precedence
• CPC Class Codes: B30B 1/24 : by rack-and-pinion means B30B9/3067 takes precedence
• CPC Class Codes: B30B 15/026 : Mounting of dies, platens or press rams
• CPC Class Codes: B30B 15/14 : Control arrangements for mechanically-driven presses

Abstract

A composite allograft press comprises a loading frame and a two piece mold to form an composite allograft and in particular an acetabular cup from impacted cancellous bone chips and cement. Pressure is applied by a manually operated lever through a rack-and-pinion gear mechanism to a plunger attached to one part of the mold. Compression load switches in-line with the plunger indicate the correct loading to the mold to produce a composite allograft in which the inner surface is smooth and comprised essentially of hardened bone cement material. The outer portion of the allograft may have limited cement extrusions but the exterior of the cup primarily shows exposed cancellous bone surface. In surgery a composite allograft; e.g., an acetabular cup, is fixed in the acetabulum with bone screws to fill an acetabular defect. A plastic liner is affixed with bone cement directly to the composite allograft cup to receive the femoral component.

Claims

1. A composite allograft, comprising:

cancellous bone chips molded and compressed with bone cement to a predetermined shape having an inner surface and an outer surface;

said inner surface consisting essentially of hardened bone cement wherein said inner surface is smooth; and

said outer surface consisting essentially of exposed cancellous bone chips wherein said outer surface is irregular.

2. The composite allograft of claim 1 adapted for use in total hip replacement in a human patient having an acetabulum having defects in the acetabulum, wherein said predetermined shape conforms substantially to the acetabulum.

3. The composite allograft of claim 2 wherein said predetermined shape is substantially hemispherical.

4. The composite allograft of claim 1, further comprising a plastic liner affixed to said inner surface.

5. The composite allograft of claim 4, wherein said plastic liner is adapted to receive a femoral component.

6. The composite allograft of claim 1, wherein said cancellous bone chips are about one cubic centimeter in size.

7. The composite allograft of claim 2, wherein said allograft is adapted to receive a plurality of bone screws whereby said allograft may be attached to the acetabulum.

8. The composite allograft of claim 2, wherein said predetermined shape comprises a circular rim around the outer edge of said allograft.