# US 5,326,376 A · Femoral stem prosthesis

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- Number: US 5,326,376 A
- Document ID: US5326376A
- Status: Granted
- Kind: A
- Application number: 08/110,741
- Filed: 1993-08-23
- Granted: 1994-07-05
- Earliest claimed: 1993-08-23
- Assignees: Zimmer, Inc.
- Inventors: David B. Warner; Leslie N. Gilbertson; Gregory S. Meadows; Kenneth S. Shipp
- Web page: https://patentgrep.com/patent/US5326376A

## CPC

- A61L 27/06: Titanium or titanium alloys
- A61F 2/30723: {Plugs or restrictors for sealing a cement-receiving space (tools for inserting plugs A61F2/4614; sealing collars for use during cementing A61B17/8808)}
- A61F 2/30724: {Spacers for centering an implant in a bone cavity, e.g. in a cement-receiving cavity}
- A61F 2/30767: {Special external or bone-contacting surface, e.g. coating for improving bone ingrowth}
- A61F 2/3662: {Femoral shafts}
- A61F 2/367: {Proximal or metaphyseal parts of shafts (trochanteric devices connected to said proximal parts A61F2/30739)}
- A61F 2/3676: {Distal or diaphyseal parts of shafts}
- A61F 2002/30153: {rectangular}
- A61F 2002/30571: {Leaf springs}
- A61F 2002/30884: {Fins or wings, e.g. longitudinal wings for preventing rotation within the bone cavity}
- A61F 2002/30892: {parallel}
- A61F 2002/30922: {Hardened surfaces}
- A61F 2002/368: {with lateral apertures, bores, holes or openings, e.g. for reducing the mass, for receiving fixation screws or for communicating with the inside of a hollow shaft}
- A61F 2002/4619: {for extraction}
- A61F 2002/4631: {the prosthesis being specially adapted for being cemented}
- A61F 2230/0019: rectangular
- A61F 2310/00023: Titanium or titanium-based alloys, e.g. Ti-Ni alloys
- A61L: METHODS OR APPARATUS FOR STERILISING MATERIALS OR OBJECTS IN GENERAL; DISINFECTION, STERILISATION OR DEODORISATION OF AIR; CHEMICAL ASPECTS OF BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES; MATERIALS FOR BANDAGES, DRESSINGS, ABSORBENT PADS OR SURGICAL ARTICLES (preservation of bodies or disinfecting characterised by the agents employed A01N; preserving, e.g. sterilising, food or foodstuffs A23; preparations for medical, dental or toiletry purposes A61K)
- 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 tapered, collarless femoral hip joint prosthesis formed of a surface hardened titanium alloy having a highly polished surface is provided.

## Claims

### Claim 1

A method for implanting a femoral hip joint prosthesis in a prepared intramedullary canal comprising the step of:
(a) providing a prosthesis having an elongated stem extending form a proximal end to a distal end and defining a first axis, said proximal end having a neck region which joins the stem at a juncture, said stem having anterior, posterior, medial, and lateral surfaces and said surfaces tapering downwardly from said juncture to said distal end; said neck region defining a second axis disposed at an obtuse angle with the first axis, and said medial surface defining a smooth arcuate path from the stem across the juncture to the neck region and said lateral surface defining an enlarged shoulder proximal said juncture; and said surfaces having a polished finish throughout such that substantially no interfacial bonding will occur between such surfaces and bone cement in contact therewith, said stem being formed of a titanium alloy and said surfaces being surface hardened after polishing such that the hardness of the surfaces is greater than an interior of the prosthesis
(b) placing cement in said intramedullary canal;
(c) inserting said prosthesis, distal end first, into said intramedullary canal such that substantially all of said stem is encapsulated within said cement;
(d) permitting said cement to set forming an interfacial bond with bone surface of said intramedullary canal and a support for said stem; and
(e) thereafter permitting said stem to subside within said cement without disrupting said interfacial bond.

### Claim 2

A method for implanting a femoral hip joint prosthesis in a prepared intramedullary canal comprising the steps of:
(a) providing a prosthesis having an elongated stem extending from a proximal end to a distal end and defining a first axis, said proximal end having a neck region which joins the stem at a juncture, said stem having anterior, posterior, medial, and lateral surfaces and said surfaces tapering downwardly from said juncture to said distal end; said neck region defining a second axis disposed at an obtuse angle with the first axis, and said medial surface defining a smooth arcuate path from the stem across the juncture to the neck region and said lateral surface defining an enlarged shoulder proximal said juncture; and said stem being formed of a titanium alloy and said surfaces being surface hardened such that said surfaces have a hardness greater than an interior of the prosthesis, said surfaces also having a polished finish throughout before being surface hardened such that substantially no interfacial bonding will occur between such surfaces and bone cement in contact therewith
(b) placing in said intramedullary canal
(c) inserting said prosthesis, distal end first into said intramedullary canal such that substantially all of said stem is encapsulated within said cement and said distal end is engaged in the open upper end of said centralizer;
(d) permitting said cement to set forming an interfacial bond with bone surface of said intramedullary canal and a support for said stem; and
(e) thereafter permitting said stem to subside within said centralizer and within said cement without disrupting said interfacial bond.

### Claim 3

A method for implanting a femoral hip joint prosthesis in an intramedullary canal comprising the steps of:
(a) providing a prosthesis having an elongated stem extending from a proximal end to a distal end, said stem tapering from a relatively larger cross-sectional size adjacent said proximal end to a smaller cross-sectional size adjacent said distal end and being formed of a titanium ally and having a polished finish having a surface roughness no greater than 4 microinches and having substantially all surfaces hardened by a surface hardening process after polishing;
(b) placing cement in said intramedullary canal;
(c) inserting prosthesis, distal end first, into said intramedullary canal such that substantially all of said stem is encapsulated within said cement
(d) permitting said cement to set forming an interfacial bond with bone surface of said intramedullary canal and a support for said stem; and
(e) thereafter permitting said stem to subside within said cement without disrupting said interfacial bond.