# US 5,755,809 A · Femoral head core channel filling prothesis

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- Number: US 5,755,809 A
- Document ID: US5755809A
- Status: Granted
- Kind: A
- Application number: 08/717,204
- Filed: 1996-09-20
- Granted: 1998-05-26
- Earliest claimed: 1995-06-07
- Assignees: Implex Corporation
- Inventors: Robert C. Cohen; Michael J. Christie
- Web page: https://patentgrep.com/patent/US5755809A

## CPC

- A61B 17/742: {having one or more longitudinal elements oriented along or parallel to the axis of the neck}
- A61F 2/28: Bones
- A61F 2/30767: {Special external or bone-contacting surface, e.g. coating for improving bone ingrowth}
- A61F 2/3094: {Designing or manufacturing processes}
- A61F 2/4601: {for introducing bone substitute, for implanting bone graft implants or for compacting them in the bone cavity}
- A61F 2002/2828: {Femoral head}
- A61F 2002/2832: {Femoral neck}
- A61F 2002/30224: {cylindrical}
- A61F 2002/30851: {Multiple threadings}
- A61F 2002/30858: {Threads interrupted by grooves or sidewalls, e.g. flat sidewalls}
- A61F 2002/30859: {having threaded portions of different pitches}
- A61F 2002/30861: {having threads of increasing or decreasing height}
- A61F 2002/30863: {the entry end surface having flutes, relief grooves, starter notches or bevelled indentations}
- A61F 2002/30871: {Trapezoidal threads}
- A61F 2002/3092: {having an open-celled or open-pored structure}
- A61F 2230/0069: cylindrical
- A61F 2310/00161: Carbon; Graphite
- A61F 2310/00544: Coating made of tantalum or Ta-based alloys
- A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D)
- A61F: FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS (dental prosthetics A61C)

## Abstract

A prosthesis for interfacing with an internal region of a bone of a given structure and function such as a femoral head and/or neck, wherein the internal region of the bone can be an avascular necrotic region. The prosthesis comprises porous filling member for filling a cored channel provided in the internal region of the bone to provide mechanical stability which preserves the function and the structure of the bone and accommodate an ingrowth of healthy vascularized bone tissue into the internal region of the bone. Also, a method for mechanically stabilizing a bone using the prosthesis.

## Claims

### Claim 1

A prosthesis for interfacing with an internal region of a femoral bone, comprising:
porous filling means for filling a cored channel provided in the internal region of a femoral head, said porous filling means comprising a unitarily formed rod-shaped member of reticulated vitreous carbon foam having tantalum deposited thereon, wherein said unitarily formed rod-shaped member has a first end, a second end, and a thread located marginally adjacent to said second end, said thread having a pitch of approximately 3 mm and substantially flat roots and crests whereby said porous filling means provides mechanical stability which preserves the function and the structure of the bone and accommodates an ingrowth of healthy vascularized bone tissue into the internal region of the bone.

### Claim 2 (depends on 1)

The prosthesis according to claim 1, wherein the internal region is an avascularized necrotic region of said femoral head and said porous filling means comprises a volumetrically large porous structure of interconnecting pores that operate as conduits which allow the healthy vascularized bone tissue to pass into the avascular necrotic region of the bone.

### Claim 3 (depends on 1)

The prosthesis according to claim 1, wherein said porous filling means comprises a bulk volume porosity between approximately 50 and 90 percent.

### Claim 4 (depends on 1)

The prosthesis according to claim 1, wherein said first end of said rod-shaped member comprises a spherical-shape.

### Claim 5 (depends on 1)

The prosthesis according to claim 1, wherein said second end of said rod-shaped member comprises means for driving said prosthesis into the cored channel of the bone.

### Claim 6

A core channel filling prosthesis for interfacing with an internal region of a femoral head to substantially prevent the femoral head from collapsing and fracturing, comprising:
a unitarily formed porous rod-shaped member having a first end, second end, and a thread located marginally adjacent to said second end, said thread having a pitch of approximately 3 mm and substantially flat roots and crests, said member for filling a cored channel provided in the internal region of the femoral head, said porous member comprising reticulate vitreous carbon foam having tantalum deposited thereon, said foam forming a volumetrically large structure of interconnecting pores which operate as conduits which allow healthy vascularized bone tissue to pass into the internal region of the femoral head, whereby said prosthesis provides mechanical stability which preserves the function and the structure of the femoral head.

### Claim 7 (depends on 6)

The prosthesis according to claim 6, wherein said first end of said porous rod-shaped member comprises a spherical-shape and said second end of said rod-shaped member comprises means for driving said device into the cored channel of the femoral head.

### Claim 8 (depends on 6)

The prosthesis according to claim 6, wherein said porous rod-shaped member comprises a bulk volume porosity of between approximately 50-90 percent.

### Claim 9 (depends on 6)

The prosthesis according to claim 6, wherein said internal region is an avascularized necrotic region of the bone.