SPLIT STEM SURGICAL SAW BLADE

LAME DE SCIE CHIRURGICALE COMPORTANT UNE TIGE FENDUE

English Abstract

This invention is a bone plug cutting blade (3) for a
peripheral drive oscillating surgical saw. The blade (3) has
a split stem (1, 2) so that it can be placed around a tendon
(11) attached to the bone (12) before being inserted into
the saw blade holder (8).

French Abstract

L'invention concerne une lame (3) de scie chirurgicale oscillante à moteur périphérique, servant à découper un bouchon osseux. Cette lame (3) possède une tige fendue (1)(2), ce qui permet de la placer autour d'un tendon (11) attaché à l'os (12) avant de l'introduire dans le support de lame de la scie.

Claims

5


CLAIMS

1. A peripherally driven bone cutting surgical blade
in operative combination with an oscillating drive mechanism,
said blade comprising an open ring with teeth protruding from a
leading edge and peripheral drive attachment means, said open
ring of teeth being closeable to form a substantially circular
teeth ring, and said oscillating drive mechanism causing the
blade to oscillate about a central longitudinal axis of the teeth
ring.

2. The blade of claim 1 in which the peripheral drive
attachment means is provided by two stems, one of said stems
being an extension of the ring on one side of the ring opening
and the other of said stems being an extension of the ring on the
other side of the ring opening, and both of said stems extending
substantially outward radially from the center of the ring.

3. The blade of claim 1, else having teeth protruding
from a trailing edge of the ring.

4. A peripherally driven bone cutting surgical blade
and blade holder in operative combination with an oscillating
drive mechanism, comprising:
an open ring with teeth protruding from a leading edge,
said ring having two stems, one of said steps being an extension
of the ring on one side of the ring opening and the other of said
stems being an extension of the ring an the other side of the
ring opening, both of said stems extending substantially outward
radially from the center of the ring, said ring and said atoms
being closeable to form a substantially circular teeth ring with
said stems being in contact with each other, and
a holder for said stems, said holder and said stems in
combination having locking means whereby stems and said holder
can be firmly locked together, and
an oscillating drive mechanism attached to the holder,
said oscillating drive mechanism causing the holder


6



and blade to oscillate about a central longitudinal axis of
the teeth ring.

Description

~O 96104855 PCTIOS95109616
Description
SPLIT STEM SU12GICAL SAW BLADE
I Background of the Invention


' 1. Field of the Invention


This invention relates in general to surgery


and specifically to bone-tendon-bone graft harvesting


l0 for knee ligament reconstruction. It would be found in


the patent files in a classification for surgical bone


cutting implements.


2. Prior Art


There has long been a need for a more


efficient means of harvesting the graft for ACL


reconstruction of the knee. In such surgery a graft


consisting of a portion of tibia bone, a portion of


patella tendon and another bone portion from the patella


is removed from the knee of the patient and


arthroscopically relocated inside the knee to replace a


damaged anterior cruciate ligament (ACL). Historically


the preferred method of bone portion removal has been


with osteotomes (chisels), leaving irregular pieces of


bone which then have to be trimmed and sized by hand to


the approximate shape of cylinders for fitting into the


drilled out tibial and femoral tunnels inside the knee.


In order to more efficiently harvest the


graft, introduce less trauma at the donor site and


provide for a better bone plug/drilled tunnel fit, the


ACL bone saw was developed (U. S. Patent Number


5,092,875). The ACL bone saw peripherally oscillates a


ring of teeth about its center by means of an attached


drive arm. Thus the ACL saw is substantially different


from a standard plug cutter in that it has no shaft and


therefore can easily be inserted into precut notches in


the tibia and patella for removal of cylindrical bone


plugs.


A device from Australia called the Helical
Tube Saw has also been developed to harvest the graft.
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It appears much the same as a standard plug cutter with
the exception of an additional helical slot open ended
at the teeth and running longitudinally along the tube.
Such a configuration allows the cutting tube to wrap
around the tendon portion of the graft as it cuts the
bone portion from the proximal end (tendon end first)
with the knee flexed to 90 degrees. The device must be
oscillated by hand and the complexity of the blade
hinders its use as a one-time only disposable item.
. However, from a physician's standpoint, it is
desirable to initiate the bone cut from the tendon end
rather than the distal bone plug end. Also, if the ACL
bone saw could be made to cut in that direction, it
would further reduce trauma at the donor site by
eliminating the need for pre-cut blade insertion
notches.
Summarv of the rnventj~~
In order to satisfy the objective of allowing
the ACL bone saw to harvest the graft by cutting the
bone portions from the tendon end first, the split stem
blade was conceived. A further object of the invention
is to provide a one-time use blade that is easy to
fabricate. A still further object is to provide such a
blade which is simple to use in that it can be easily
inserted into the blade holder, positively locked, and
then easily removed without the need for additional
tools.
The split stem blade satisfies all the
objectives of the invention. Instead of having a closed
ring of teeth, the split stem blade has an open teeth
ring with two stems, one on each side of the opening.
During the ACL reconstruction procedure the split stem
concept allows the surgeon to slip the open blade around
the graft tendon portion, close the blade and push the
stems into the blade holder. The first bone portion can
then be cut, its end separated by an osteotome and that
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WO 96104855 PCT/US95109616
3
portion of the graft pulled back through the saw blade.
The saw can then be turned around, the graft slipped
back through the blade end the second bone portion can
then be removed by the same process.
Brief Describtion of tr,p nra~..in~
Fig. 1 is a front view isometric drawing
showing the entire blade.
Fig. 2 is a top view showing the blade in its
.closed position.
Fig. 3 is a front view isometric drawing
showing the blade in its holder with a tendon passing
through the blade and attached to a bone.
Fig. 4 is a side view of a self-entering
version of the blade.
Detained Descrsption
The blade as shown in its open configuration
in Fig. 1 has two slotted stems 1 and 2. When squeezed
together the two stems form a single split blade stem
and the toothed portion becomes a circular ring 3 having
an inside diameter of either 8, 9, 10 or 11 mm. to
accommodate different sized patients. The split stem
configuration is actually easier to fabricate than a
closed ring with a stem attached. The stems are tapered
slightly so as to be easily inserted into the blade
holder and they are also bent outward slightly at the
slots 4 and 5 to form tabs 6 and 7 as shown in Fig. 2.
Insertion of the blade into the holder 8 of Fig. 3
causes the tabs to be pushed back together until they
pass the lower stop 9 of the holder, at which point the
tabs are allowed to snap apart and thereby prevent the
blade from moving downward while the top of the blade
stem contacts the holder's upper stop 10 and thereby
prevents the blade from moving upward. Thus the blade's
own spring force is used to lock the blade into place.
To remove the blade the tabs are simply squeezed
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together and the blade pulled out. Fig. 3 shows a
tendon portion 11 passing through the blade and attached
to the bone 12 from which the bone plug is to be cut.
Fig. 4 illustrates an alternative version of
the blade which includes a tapered teeth ring with a
second set of teeth 13 around the back of the blade. By
tilting this blade forward and back while cutting
forward and back the surgeon can cause the blade to
self-enter or self-exit the bone, thereby eliminating
.the need for an osteotome to separate the bone plugs at
their ends.
what is claimed is:
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Representative Drawing