U.S. patent number RE28,502 [Application Number 05/467,147] was granted by the patent office on 1975-08-05 for intramedullary rod.
This patent grant is currently assigned to The Sampson Corporation. Invention is credited to William C. Allen, Albert H. Burstein.
United States Patent |
RE28,502 |
Burstein , et al. |
August 5, 1975 |
Intramedullary rod
Abstract
An intramedullary rod for internal fixation of long bone
fractures in the form of an elongated hollow tube having
longitudinal flutes about the periphery. Each end is
.[.castellated.]. .Iadd.formed .Iaddend.to provide .[.alternate.].
.Iadd.a plurality of .Iaddend.sharp cutting surfaces and .Iadd.an
.Iaddend.angled face guide .[.projections.]. .Iadd.means
.Iaddend.to facilitate emplacement in the medullary canal.
Inventors: |
Burstein; Albert H. (Shaker
Heights, OH), Allen; William C. (Gainesville, FL) |
Assignee: |
The Sampson Corporation
(Pittsburgh, PA)
|
Family
ID: |
27276214 |
Appl.
No.: |
05/467,147 |
Filed: |
May 6, 1974 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
Reissue of: |
301473 |
Oct 27, 1972 |
03783860 |
Jan 8, 1974 |
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Current U.S.
Class: |
606/62 |
Current CPC
Class: |
A61B
17/72 (20130101); A61B 17/7283 (20130101) |
Current International
Class: |
A61B
17/72 (20060101); A61B 17/68 (20060101); A61f
005/04 () |
Field of
Search: |
;128/92BC,92BB,92BA,92B,92R,92EC,92D ;85/13,19 |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Down Bros. and Mayer & Phelps, Ltd., Surgical Catalogue, p.
G20, 1966. .
Journal Bone & Joint Surgery, Nov. 1951, page 11..
|
Primary Examiner: Gaudet; Richard A.
Assistant Examiner: Yasko; J.
Attorney, Agent or Firm: Dennison, Dennison, Townshend &
Meserole
Claims
We claim:
1. An intramedullary rod for fracture fixation comprising an
elongated hollow tube open at each end and hollow throughout, said
tube having at least one end surface castellated and defined by a
plurality of longitudinal projections, a first group of said
projections having pointed, relatively sharp, end surfaces defining
cutting faces, a second group of said projections being spaced
alternately with said first set of projections and having angled
flat end surfaces defining guiding faces.
2. An intramedullary rod as defined in claim 1, wherein each end
surface of said tube is castellated.
3. An intramedullary rod as defined in claim 1, wherein said tube
is provided with a plurality of longitudinally extending elongated
flutes about the external surface thereof.
4. An intramedullary rod as defined in claim 3, wherein the flutes
extend longitudinally and join the first group of projections.
5. An intramedullary rod for fracture fixation comprising an
elongated tube open at each end and hollow throughout, a plurality
of longitudinally extending elongated flutes about the external
surface of said tube, on at least one end face of said tube the
flutes being sharply sloped inwardly at an acute angle to define a
plurality of cutting surfaces, the tube portions intermediate said
flutes having their end surfaces on said one end face sloped
gradually inwardly at an obtuse angle to define a plurality of
guide surfaces.
6. An intramedullary rod as defined in claim 5 and including a
rectangular slot in the tube wall surface for reception of a
retraction tool. .Iadd. 7. An intramedullary rod for fracture
fixation comprising an elongated tube open at each end and hollow
throughout, a plurality of longitudinally extending elongated
flutes about the external surface of said tube, on at least one end
face of said tube the flutes being sharply sloped inwardly at an
acute angle to define a plurality of cutting surfaces, guide means
extending axially from said one end face beyond said cutting
surfaces and having a guide surface sloped gradually inwardly at an
obtuse angle..Iaddend.
Description
BACKGROUND OF THE INVENTION
This invention relates generally to a tool for use in orthopedic
surgery and more specifically to a new intramedullary rod or nail
for use in surgical fracture fixation to maintain the fractured
portions of long bones together.
In the field of orthopedic surgery it has become common practice in
certain situations to use as a fracture fixation means an elongated
nail or rod, commonly known as an intramedullary rod. Such a rod is
driven into the narrow cavity or medullary passage longitudinally
in a fractured bone after lateral reduction and serves to hold the
severed parts thereof in longitudinal alignment incident to
knitting and healing of the fracture. Such nails or rods are
generally used in treatment of long bone fractures, and, for
example, in treatment of the fracture of the femur, the nail or rod
is driven percutaneously longitudinally through the tip of the
trochanter and into the medullary canal and serves to bridge the
point of fracture in the stem on either side thereof.
Intramedullary rods are known in various forms but it has been most
satisfactory in obtaining a solid and secure joinder of fractured
bones by using a rod which will not twist or turn within the narrow
passage of the bone. The ideal function of an intramedullary rod is
to hold the proximal and distal fragments of the bone which has
been fractured in correct alignment during the process of healing.
Several types of loads must be transmitted from the distal to the
proximal fragments, these include compression, bending and torsion.
The compressive loads are transmitted generally directly through
the bone surface, while torsional and bending loads are transmitted
at least in part by the intramedullary rod. In order to properly
transmit torque, the rod or nail must be capable of tightly
gripping both the proximal and distal fragments. Additionally, the
nail must be sufficiently rigid to prevent excessive bending at the
fracture site.
The current nail designs available on the market today do not
accomplish all of the functions necessary in the ideal rod as
described above. Among the designs presently available are the
Kuntscher, Schneider, and Hansen-Street nails or rods. Several of
these designs rely on friction gripping and are of open section
design which does not have sufficient torsional rigidity. Ideally,
the rod should be of such design and strength as to approach the
strength of the healed bone.
SUMMARY OF THE INVENTION
The new intramedullary rod disclosed herein is of generally hollow
internal construction and is provided with flutes extending
longitudinally on the external surface thereof. A novel
.[.castellated.]. end configuration is provided on each of the ends
of the rod providing a guiding-cutting tip to enable the nail to be
inserted in the medullary canal with greater facility and to enable
the material displaced during insertion of the rod to pass within
the rod itself. This construction provides a stronger rod and the
most efficient compromise in shape for maximum torsional and
bending strength within the confines of bone geometry.
An object of the present invention is to provide an intramedullary
nail having a high strength both in bending and in torsion
comparable to the strength of the normal femur to thereby make
early mobilization practical without fear of bending the nail.
It is a further object of this invention to provide an
intramedullary nail having similar end configurations so that the
same may be introduced either through the fracture in a retrograde
manner or through a proximal insertion over the distal femoral
neck.
A further object of this invention is to provide a high strength
hollow intramedullary rod having a fluted external surface to allow
maximal intramedullary gripping.
Yet a further object of the invention is to provide a cutting
surface on the advancing edge of the flutes of an intramedullary
rod in order to cut through bone to prevent splitting or
wedging.
Another object of this invention is to provide an intramedullary
rod that requires only a driver for insertion which may be
manufactured in various diameters and lengths.
It is another object of the present invention to provide an
intramedullary rod that has the advantage of being able to grip all
around the endosteal surface of a bone without completely filling
the endosteal volume.
Another object of the invention is to provide an intramedullary rod
which requires less force for insertion since material is being
cut.
Another object of the invention is the provision of a novel hollow
intramedullary rod which is of generally simple construction, is
relatively inexpensive to manufacture, and is safe and efficient in
use.
The above and other objects and features of the invention will
become more apparent from a consideration of the following
disclosure.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a side elevation of the right human lower limb showing a
portion thereof incised and the opening retracted to show a portion
of the trochanter and neck of the femur with the remainder of the
bones of the leg and the intramedullary rod shown in phantom.
FIG. 2 is a side elevation of a fractured human femur showing the
intramedullary rod of the present invention in position in the
medullary canal.
FIG. 3 is a side elevation of the intramedullary rod of the present
invention with selected portions shown in cross section.
FIG. 4 is an enlarged end view of the intramedullary rod shown in
FIG. 3.
FIG. 5 is an enlarged perspective view of the end portion of the
intramedullary rod.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The intramedullary rod of the present invention is shown generally
at 10 and as will be noted from FIG. 3 is preferably in the form of
an elongated hollow tube 11 having a cylindrical bore 12 extending
longitudinally therethrough. The rod may be formed of any metallic
substance compatible with human tissue.
A plurality of longitudinal circumferentially spaced flutes 13
extend about the circumference of the rod and terminate at either
end in inwardly sharply sloped cutting points 14. As will be
apparent from FIG. 5, the end surface of the cutting points slopes
inwardly and downwardly toward the center of the rod resulting in a
relatively sharp cutting chisel point construction. Intermediate
the flutes 13, the end surface is castellated to provide guiding
projections 16. These projections have straight side walls 17 and
the end faces thereof slope downwardly and outwardly from the inner
surface to the outer face of the rod in a manner opposite to the
slope of the cutting point 14. It will be noted that the
projections 16 extend longitudinally beyond the points 14. Note the
sloping end face 18 which is preferably cut at an angle of
approximately 45.degree. from the horizontal as shown in FIG. 5.
This end face configuration on projection 16 provides a guiding
surface and as will be apparent from a study of FIG. 4, the outer
edge of the guiding projections is spaced radially inwardly from
the outermost edge of the cutting points 14.
Each end of the hollow tube 11 is preferably provided with a
recessed counterbore 19 which, if desired, may be internally
threaded for reception of a conventional extractor. A preferred
extractor arrangement includes provision of an extractor slot 20
formed intermediate to adjacent flutes and taking the form of a
rectangular through slot. Conventional extraction means known in
the art may be inserted through the opening or slot 20 to aid in
removal of the intramedullary rod.
A typical fracture of a femur F is shown in FIG. 2 wherein the
distal end of the bone is shown at 21 and the proximal end at 22.
In order to insert the rod, under surgical conditions an incision
is made adjacent to the hip exposing the trochanter and the tissues
may be held retracted by means of conventional retractors R. A
reamer or drill may then be applied to provide a longitudinal
passageway through the bone passing through both dense compact
cortical bone as well as cancellous bone.
The intramedullary rod is then inserted into the medullary canal
through the trochanter 23 as shown in FIGS. 1 and 2, and with
application of percussive force the rod is passed downwardly
extending into the distal end 21 of the bone. The cutting points 14
on the flutes 13 serve to cut into the wall of the hole formed by
the reamer or drill. The guiding surfaces 18 on the castellated
projections 16 guide the intramedullary rod and prevent it from
cutting out of the bone. This particular end arrangement also
serves to channel loose material and extrude the same into the
hollow internal portion 12 of the rod 11. The material of the bone
which is cut by the points 14 being generally cortical will then
pass into the cavity 12. The flutes provide a means for gripping
the bone both proximal and distal to the fixation site. This will
allow better transmission of torque across the generally
torsionally unstable fixation. The mechanical locking provided is a
superior method to the frictional system as employed in the prior
art Kuntscher rods and provides a better result than the
self-broaching technique of the Schneider nail since there is less
chance of the rod cutting through the bone due to the presence of
the guiding surfaces provided herein. An additional advantage is
that less force is needed for insertion since less material is
being cut.
The present intramedullary rod has the advantage of being able to
grip all around the endosteal surface of the bone without
completely filling the endosteal volume since the nail is hollow.
The hollow structure presents the most efficient compromise in
shape for maximum torsional and bending strength within the
confines of bone geometry.
It is also contemplated that the hollow feature will permit
insertion of viscous fluids into the distal segment of the bone.
Methylmethacrylate has recently been used in such procedures and
may be applied through the proximal end which has been exposed.
Utilizing such a technique, the rod may serve as a permanent bone
bridge in cases where nonunion persists. Generally, however, after
knitting of the bone structure, the rod 10 is drawn out of the
marrow passage.
It is apparent that the strength and rigidity of the proposed rod
may be regulated by design parameters relative to the inside and
outside diameters and length. Accordingly, a large diameter rod may
be made without excessive rigidity which might produce delayed
union of the fracture.
After the bone portions have knit and healed, a subsequent
operation may be performed to expose the extractor slot 20 for
application of a conventional extractor tool to withdraw the rod
from the medullary canal. Alternatively, the recessed counterbore
19 may be provided with internal threads for reception of a
threaded insert for this purpose.
It will be apparent that both ends of the rod have similar
configurations and therefore the rod may be introduced either
through the fracture in a retrograde manner or through a proximal
insertion over the distal femoral neck. During insertion, the
advancing edge of the flutes 13 and their associated cutting points
14 cut through the bone so that unlike prior art nails splitting of
the shaft or wedging of the rod so that it sticks is clearly
minimized.
While we have described our intramedullary rod in specific detail,
it will be apparent that the same may be modified or varied in many
respects without departing from the invention, and therefore other
variations and alterations may come within the scope of the
following claims.
* * * * *