U.S. patent number 3,843,975 [Application Number 05/348,936] was granted by the patent office on 1974-10-29 for prosthesis for femoral shaft.
Invention is credited to Raymond G. Tronzo.
United States Patent |
3,843,975 |
Tronzo |
* October 29, 1974 |
PROSTHESIS FOR FEMORAL SHAFT
Abstract
A prosthesis for femoral shaft having a ball at one end, a
medullary stem at the other end, a neck connecting the ball to the
stem, a head at the connection between the stem and the neck and
including means for fastening the prosthesis to the femur and
outrigger knives on the head on either side of the head oriented to
dig into the femur, from the side so that the bone fits between the
knives.
Inventors: |
Tronzo; Raymond G.
(Philadelphia, PA) |
[*] Notice: |
The portion of the term of this patent
subsequent to May 7, 1991 has been disclaimed. |
Family
ID: |
23370211 |
Appl.
No.: |
05/348,936 |
Filed: |
April 9, 1973 |
Current U.S.
Class: |
623/23.27 |
Current CPC
Class: |
A61F
2/3662 (20130101); A61F 2/30739 (20130101); A61B
17/32 (20130101); A61F 2/30767 (20130101); A61F
2002/30841 (20130101); A61F 2/367 (20130101) |
Current International
Class: |
A61F
2/30 (20060101); A61F 2/36 (20060101); A61B
17/32 (20060101); A61f 001/24 () |
Field of
Search: |
;128/92C,92CA,92R,92EC |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Other References
Vitallium Surgical Appliances Catalog, Austenal Company, Howmet
Corp. New York, N.Y., copyright 1964, Young Mechanical Knee/No.
6661, page 31. .
"New Stainless Steel Intramedullary Femoral Head-Neck Prosthesis"
M-1776-Leinbach Modification of J. Gosset type, advertisement, page
16 of American Ossacryl Co., "The Journal of Bone & Joint
Surgery," Vol. 37A, Jan. 1955..
|
Primary Examiner: Gaudet; Richard A.
Assistant Examiner: Frinks; Ronald L.
Attorney, Agent or Firm: Jackson, Jackson & Chovanes
Claims
Having thus described my invention, what I claim as new and desire
to secure by Letters Patent is:
1. In a prosthesis for a femoral shaft fixation, a ball at one end,
a medullary stem at the other end, a neck connecting the ball and
the stem, a head at the connection between the stem and the neck
and including means for fastening the medullary stem to the bone
and outrigger knives on the head, oriented for insertion into the
bone, having on the outside surface of the medullary stem from 20
to 50 percent pore area, at least 100 microns in depth of pores,
between 20 and 40 percent of the surface pore area being small
pores of between 50 and 200 microns diameter, between 20 and 40
percent of the surface pore area being intermediate pores of
between about 200 and 800 microns in diameter, and between 20 and
40 percent of the surface pore area being large pores exceeding 800
and not exceeding 3500 microns in diameter.
Description
DISCLOSURE OF INVENTION
The invention contemplates a prosthesis for making femoral shaft
for use primarily in the total prosthesis of a hip joint but
permissibly on the partial prosthesis. It is for use in making
implants in mammals such as human beings and higher animals in
veterinary surgery, particularly experimental animals such as
dogs.
In making a femoral shaft, the ball on the femur is removed by
surgery and must be replaced by an implant or prosthesis.
Most of the implants are part of total hip joint replacements, but
on occasion they may be used as femoral head components
exclusively.
My invention particularly involves a new prosthesis making an
intermedullary fixation by inserting this prosthesis in the
sawed-off femur so that it will complete an artificial hip
joint.
One purpose is to insert a new femoral component having a medullary
extension at one end, a head at the top of the medullary extension,
outrigger knives from the head extending toward the bone and a neck
connected with a ball at the top.
A further purpose is to coat the medullary extension with a porous
material having three sizes of pores, small, medium and large, and
distributing them according to the later development of this
application.
In the invention FIG. 1 is a section showing the prosthesis
inserted in the femur bone.
FIG. 2 is a front view of the prosthesis by itself.
FIG. 3 is a side view of the prosthesis.
In the invention the femur 10 is cut off by removing its ball from
the top and cutting down so that the new prosthesis will complete
the joint making the substitute femur of the same approximate
length as the original femoral neck and head.
In the new prosthesis, a medullary stem 12 is provided at one end
and a ball 14 which will mate in a socket in the acetabulum, either
the natural socket or a substitute socket is provided at the other
end. The ball is joined to the medullary extension by a neck 16.
Adjoining the top of the medullary extension and connecting the
medullary extension to the neck, is a head 18. The greater
trochanter 29 is attached to the prosthesis by screws 20 in holes
22.
On either side of this head and oriented toward the femur are
outriggers 24 which are knives having triangular blending knife
edges 26 to a point 28 for extra-medullary fixation.
There is a socket 30 on the top of the head and suitably threaded
to receive a tool (not shown) which is adapted to be hit with a
hammer at its upper end to force the medullary component 12 into
the medullary cavity of the femur and also the knife edges of
outriggers 24 into the bone so that the correct position can be
assumed by the head to receive the screws 20, and thereby prevent
rotation of the prosthesis within the femur. The effect is to
engage the bone at the side.
The size of the medullary extension will be varied lengthwise and
widthwise so that several sizes will be available to suit the
individual patient's femur. Accordingly, the stem will be tightly
fitted to the femur for immediate fixation on a press-fit basis,
thus allowing bone to grow appropriately into the graded pores.
On the medullary extension but preferably not on the knives, the
head, the neck and the ball, I preferably put a porous coating
which is at least 100 microns thick, preferably at least
one-sixteenth of an inch and most desirably at least one-eighth of
an inch. All four sides or any one side may be coated with a porous
surface, preferably the back, and the two lateral ones, leaving the
medial one plain. This is done to facilitate removal. This porous
coating is preferably made of metallic powders applied by metallic
spray technique such as that described in Welding Handbook, Third
Edition, although it could be made of ceramic or plastic applied by
suitable technique.
The important thing from the standpoint of the present invention is
that the porosity is at least 20 to 50 percent, preferably 30 to 40
percent and most desirably 33 percent of the total surface.
The pores in size must be divided between small, intermediate and
large pores, and at the surface from 20 to 40 percent of the pore
area, preferably from 30 to 36 percent and most desirably 33
percent must be in each category, large, intermediate and small
pores. For the purpose of this invention small pores have a
diameter between 50 and 200 microns, preferably 75 to 125 and most
desirably about 100 microns. Pores smaller than this are largely
ineffective for bone growth.
The intermediate pores are in the range of from 200 to 800 microns
in diameter.
The large pores are larger than 800 microns in diameter and not
larger than 3500 microns.
Additional disclosure regarding the porous bone implant is
contained in my application, Ser. No. 228,052, filed Feb. 22, 1972
for "Bone Implant with Porous Exterior Surface," now abandoned and
Ser. No. 342,461, filed Mar. 19, 1973 for "Bone Implant with Porous
Exterior Surface."
It will be understood that the medullary extension of the
prosthesis has a tendency to promote interlocking of bone growth,
the small pores anchoring initially with the bone having a tendency
to receive initial bone growth, but the intermediate and large
pores have a tendency to receive more substantial and firm bone
growth.
The coating may be of particles of stainless steel, for example 8
percent of nickel and 18 percent of chromium or for example 16
percent chromium, the balance in each case being iron.
The coating may also to advantage be Vitallium, a cobalt chromium
molybdenum alloy of which one example is the following:
cobalt 62 1/2%
chromium 31.2%
molybdenum 5.1%
manganese 0.5%
silicon 0.3%
carbon 0.4%
The Vitallium alloys have the following range:
cobalt 62.0 - 65.0%
chromium 27.0 - 35.0%
molybdenum 5.0 - 5.6%
manganese 0 - 0.6%
iron 0 - 1%
nickel 0 - 2%
silicon 0 - 0.6%
carbon 0 - 0.4%
The powder metallurgy material may also be of titanium or titanium
alloy.
As an option, I may have plastic or ceramic porous material on the
prosthesis.
In view of my invention and disclosure, variations and
modifications to meet individual whim or particular need will
doubtless become evident to others skilled in the art, to obtain
all or part of the benefits of my invention without copying the
apparatus shown, and I therefore claim all such insofar as they
fall within the reasonable spirit and scope of my claims.
* * * * *