Implant with reinforced resorbable stem

• US 5,571,193 A
• Filed: 06/11/1992
• Issued: 11/05/1996
• Est. Priority Date: 03/12/1992
• Status: Expired due to Fees

• Current Assignee: Stanley L. Kampner
• Original Assignee: Stanley L. Kampner
• Inventors: Kampner, Stanley L.
• Primary Examiner(s): Prebilic, Paul B.
• Application Number:
  US07/897,197
• Time in Patent Office: 1,608 Days
• Field of Search: 623/16, 623/17, 623/18, 623/19, 623/20, 623/21, 623/22, 623/23, 606/76, 606/77
• US Class Current: 623/23.57
• CPC Class Codes: A61B 17/86 Pins or screws or threaded wires; nuts therefor A61B17/72 take precedence
• CPC Class Codes: A61B 2017/00004 (bio)absorbable, (bio)resorbable, resorptive for implantable prostheses A61F2210/0004
• CPC Class Codes: A61F 2/30734 Modular inserts, sleeves or augments, e.g. placed on proximal part of stem for fixation purposes or wedges for bridging a bone defect
• 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 2/3603 implanted without ablation of the whole natural femoral head endoprosthetic cartilage A61F2/30756
• CPC Class Codes: A61F 2/3662 Femoral shafts
• CPC Class Codes: A61F 2/38 for elbows or knees
• CPC Class Codes: A61F 2/3859 Femoral components
• CPC Class Codes: A61F 2/389 Tibial components A61F2/3868 takes precedence
• CPC Class Codes: A61F 2/40 for shoulders
• CPC Class Codes: A61F 2002/30062 (bio)absorbable, biodegradable, bioerodable, (bio)resorbable, resorptive
• CPC Class Codes: A61F 2002/30112 Rounded shapes, e.g. with rounded corners
• CPC Class Codes: A61F 2002/30153 rectangular
• CPC Class Codes: A61F 2002/30331 made by longitudinally pushing a protrusion into a complementarily-shaped recess, e.g. held by friction fit
• 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 2002/30919 Sleeves
• CPC Class Codes: A61F 2002/3401 with radial apertures, e.g. radial bores for receiving fixation screws
• CPC Class Codes: A61F 2002/3495 Spherical shell significantly smaller than a hemisphere, e.g. extending over less than 160 degrees
• CPC Class Codes: A61F 2210/0004 : bioabsorbable
• 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 2230/0004 : Rounded shapes, e.g. with rounded corners
• CPC Class Codes: A61F 2230/0019 : rectangular
• CPC Class Codes: A61F 2310/00017 : Iron- or Fe-based alloys, e.g. stainless steel
• 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
• CPC Class Codes: A61F 2310/00179 : Ceramics or ceramic-like structures
• CPC Class Codes: A61F 2310/00239 : containing zirconia or zirconium oxide ZrO2
• CPC Class Codes: Y10S 623/908 : Bone

Abstract

A prosthetic implant for a bone joint has an anchor formed of a resorbable sleeve reinforced with a nonresorbable core. Also disclosed are methods of installation.

Claims

1. An anchor for a bone joint implant adapted to be inserted in a cavity defined by a bone and having a given cross section for affixing the implant to the bone without substantial motion of the implant relative to the bone after affixation, the anchor comprising:

a nonresorbable core sized for insertion in the cavity and having a cross section sufficiently smaller than the cross section of the cavity so that contact between the bone and the core is prevented; and

a resorbable sleeve applied to the core and having a size so that it tightly engages the cavity in the bone to thereby immovably secure the anchor to the bone.

2. The anchor of claim 1 further comprising:

a permanent, articulating implant component having a surface to contact the bone and a surface to interact with a cooperating surface of a joint; and

a securing means for joining the articulating implant component to the core.

3. The anchor of claim 2 wherein the securing means comprises a taper lock.

4. The anchor of claim 1 wherein the core is formed of a metal alloy selected from a group consisting of titanium-6-aluminum-4-vanadium, cobalt-chromium, and stainless steel.

5. The anchor of claim 1 wherein the resorbable sleeve is formed from a material selected from a group consisting of polymers of glycolic acid, polymers of lactic acid, polyamides of α

-amino acids, polyglycolic acid, polylactic acid-polyglycolic acid copolymers, polyetheretherketone (PEEK), polyorthoester, polycarbonate, calcium hydroxyapatite and tricalcium phosphate.

6. The anchor of claim 1 wherein the anchor is part of a prosthetic hip.

7. An implant for a bone joint comprising:

a component defining an operative portion of the joint, the component having an interface facing generally away from the joint and adapted to be placed into intimate contact with an actual bone to which the component is to be fixed, at least part of the interface including means promoting bony ingrowth when the interface is in intimate contact with the natural bone; and

an anchor connected to the component and adapted to be inserted in a cavity in the bone for orienting and immovably fixing the component to the bone immediately upon implantation, the anchor comprising;

a relatively high strength, permanent core having a cross section sufficiently smaller than the cross section of the cavity so that contact between the bone and the core is prevented;

an outer layer applied to the core and shaped so that the layer, upon implantation, securely engages a bone surface defining the cavity, the layer being constructed of biodegradable material so that it resorbs after a period of time and thereby vacates a portion of the cavity; and

whereby, after the layer has resorbed, the core of the anchor is spaced from and out of contact with the bone surface defining the cavity so that substantially no load transference between the bone surface defining the cavity and the core takes place.

8. The implant of claim 7 further comprising means for removably securing the anchor to the component.

9. The implant of claim 8 wherein the securing means comprises a taper lock defined by the component and the core.

10. The implant of claim 7 wherein the component comprises a joint socket.

11. The implant of claim 7 wherein the component comprises a convex surface adapted to cooperate with a concave surface of another joint member.

12. The implant of claim 11 wherein the convex surface is defined by a ball joint member.

13. The implant of claim 12 wherein the component further includes a body connected with the ball and defining the interface.

14. The implant of claim 13 including means for detachably securing the body and the ball to each other.

15. The implant of claim 7 wherein the outer layer is removably connected to the core to enable the selection of the outer layer from a supply of differently formed outer layers and thereby fit the outer layer to the shape of the cavity.

16. An implant for a bone joint comprising:

a component defining an operative portion of the joint, the component including a ball joint member, a body having an interface facing generally away from the joint and adapted to be placed into intimate contact with an actual bone to which the component is to be fixed, at least part of the interface including means promoting bony ingrowth when the interface is in intimate contact with the natural bone and means for detachably securing the ball joint member and the body to each other; and

an anchor connected to the component and adapted to be inserted in a cavity in the bone for orienting and immovably fixing the component to the bone immediately upon implantation, the anchor comprising;

a relatively high strength, permanent core having a cross section sufficiently smaller than the cross section of the cavity so that contact between the bone and the core is prevented;

an outer layer applied to the core and shaped so that the layer, upon implantation, securely engages a bone surface defining the cavity, the layer being constructed of biodegradable material so that it resorbs after a period of time and thereby vacates a portion of the cavity; and

whereby, after the layer has resorbed, the core of the anchor is spaced from and out of contact with the bone surface defining the cavity so that substantially no load transference between the bone surface defining the cavity and the core takes place.