Hole caps for prosthetic implants

• US 5,725,580 A
• Filed: 07/11/1996
• Issued: 03/10/1998
• Est. Priority Date: 12/16/1994
• Status: Expired due to Term

• Current Assignee: Exactech, Inc.
• Original Assignee: Exactech, Inc.
• Inventors: Cloutier, Raymond J., Mauldin, Cary M.
• Primary Examiner(s): Willse, David H.
• Application Number:
  US08/680,276
• Time in Patent Office: 607 Days
• Field of Search: 623/16, 623/18, 623/22, 623/23, 292/256.63
• US Class Current: 623/16.11
• CPC Class Codes: A61B 17/685 Elements to be fitted on the end of screws or wires, e.g. protective caps
• CPC Class Codes: A61B 17/86 Pins or screws or threaded wires; nuts therefor A61B17/72 take precedence
• CPC Class Codes: A61F 2/30744 End caps, e.g. for closing an endoprosthetic cavity
• CPC Class Codes: A61F 2/389 Tibial components A61F2/3868 takes precedence
• CPC Class Codes: A61F 2002/30113 circular
• CPC Class Codes: A61F 2002/30169 Pi-shaped
• CPC Class Codes: A61F 2002/30433 using additional screws, bolts, dowels, rivets or washers e.g. connecting screws
• CPC Class Codes: A61F 2002/305 Snap connection
• CPC Class Codes: A61F 2002/30571 Leaf springs
• CPC Class Codes: A61F 2002/30594 slotted, e.g. radial or meridian slot ending in a polar aperture, non-polar slots, horizontal or arcuate slots
• CPC Class Codes: A61F 2002/30682 Means for preventing migration of particles released by the joint, e.g. wear debris or cement particles
• CPC Class Codes: A61F 2002/30772 Apertures or holes, e.g. of circular cross section
• CPC Class Codes: A61F 2002/30878 with non-sharp protrusions, for instance contacting the bone for anchoring, e.g. keels, pegs, pins, posts, shanks, stems, struts
• CPC Class Codes: A61F 2002/30978 using electrical discharge machining [EDM]
• CPC Class Codes: A61F 2002/4631 the prosthesis being specially adapted for being cemented
• CPC Class Codes: A61F 2220/0025 Connections or couplings between prosthetic parts, e.g. between modular parts; Connecting elements
• CPC Class Codes: A61F 2220/0041 using additional screws, bolts, dowels or rivets, e.g. connecting screws
• CPC Class Codes: A61F 2230/0006 circular
• CPC Class Codes: A61F 2230/0047 Pi-shaped
• CPC Class Codes: A61F 2310/00023 Titanium or titanium-based alloys, e.g. Ti-Ni alloys
• CPC Class Codes: A61F 2310/00029 : Cobalt-based alloys, e.g. Co-Cr alloys or Vitallium

Abstract

An apparatus and method of use directed towards protective and supportive hole caps for prosthetic implant devices are disclosed. The present hole cap supports a prosthesis and provides a physical barrier between the prosthesis and underlying bone matter. In a preferred embodiment, the hole cap includes at least one compression spring formed along the perimeter of the cap. The compression spring maintains the hole cap within a counter-bored hole after the hole cap is inserted within the counter-bored hole. In accordance with the present invention, the compression spring deflects slightly towards the center of the hole cap when the cap is inserted within the counter-bored hole. The compression spring provides sufficient compression force against the sidewalls of the counter-bored hole to thereby hold the hole cap in place within the hole. The counter-bored hole is preferably shaped to snugly receive the outer perimeter of the hole cap. Alternative configurations are disclosed for maintaining the hole cap within an associated hole formed in the implant. The hole caps are used for covering holes in implants affixed to a patient'"'"'s body with or without the use of bone screws. The hole caps prevent the flow of unwanted debris into the counter-bored hole and into the patient'"'"'s underlying bone matter.

Claims

1. A hole cap for a prosthetic implant, comprising:

a. a substantially flat disk having a disk shaped inner region surrounded by an annular shaped perimeter region the disk shaped inner region having a smooth voidless surface; and

b. at least one compression spring formed by a slot cut into the perimeter region of the disk, wherein the compression spring extends slightly beyond an outer diameter of the disk, but is deflected into an area defined by the slot, and wherein the cap is shaped to be received by a substantially round counter-bored hole formed into a prosthetic implant, the counter-bored hole having an inner bore and a larger outer bore such that said disk shaped inner region of the hole cap forms a substantially continuous surface along the prosthetic implant over the inner bore of the counter-bored hole and the slot cut into the perimeter region lies entirely over an area of the counter-bored hole between respective perimeters of the outer bore and inner bore, whereby debris is prevented from passing through said slots from above the disk to an area below the disk when the hole cap is inserted into the counter-bored hole.

2. The hole cap of claim 1, wherein the hole cap is substantially round.

3. The hole cap of claim 1, wherein the at least one compression spring includes a protrusion which extends the spring slightly beyond the outer diameter of the disk.

4. The hole cap of claim 1, wherein the disk comprises titanium alloy.

5. The hole cap of claim 1, wherein the disk comprises cobalt chromium alloy.

6. The hole cap of claim 1, wherein the counter-bored hole includes a cap insertion ramp, and wherein the insertion ramp has an inclined surface which assists insertion of the cap into the hole.

7. The hole cap of claim 1 wherein the diameter of the disk-shaped inner region is slightly smaller than the diameter of the annular shaped perimeter region.

8. The hole cap of claim 1 wherein a bottom outer edge of the peripheral region of the cap is rounded to facilitate insertion of the cap into the counter-bored hole.

9. The hole cap of claim 1 wherein the ratio of an external diameter of the cap at the uncompressed compression spring to a diameter of the outer bore is between 1.001 and 1.009.