Note: Descriptions are shown in the official language in which they were submitted.
20~2573
PINLESS EXTERNAL FIXATION DEVICE
Field of the Invention
This invention relates to a pincers for orthopedic purposes
and in particular to a bone gripping pincers having jaws, legs
and a hinge which can be locked to secure the jaws in a desired
position. The invention further relates to-an osteosynthetic
setting device comprising a plurality of such pincers joined to a
support bar.
Background
For treating broken bones, particularly for setting bones or
bone fragments, a number of osteosynthetic devices are available
to the surgeon.
In recent years, a trend from conservative to operative
surgical fracture treatment has been clearly evident. At the
beginning of operative fracture treatment, optimum reconstruction
of the fracture was in the foreground. No great attention was
paid to the blood supply and the soft parts around the fracture.
Efforts were made to achieve total stability without
consideration for biology. With the spread of intramedullar
nailing, it was recognized that total stability of the fracture
is not absolutely necessary. Despite somewhat greater
instability of the fracture, the minimally disrupted biology
could heal the fracture. This new knowledge was also taken into
consideration in other types of osteosynthesis. In plate
osteosynthesis, for example, fewer screws and smaller and shorter
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plates are used. The same applies to external fixation devices.
Instead of huge multi-dimensional structures with interfragment
tension bolts, the simple unilateral setting device became
accepted.
Despite the "biological~ use of the external fixation
device, the fracture does not always heal. This means that the
fracture must often be treated with a second operation and
another osteosynthetic method. The principal reason for
complications are the nails or screws that are driven from
outside through the skin and the soft tissue into the bone.
Along these nails or screws, germs get into the bone, which leads
to what is known as a "Pintrak infection.~ If such an infection
occurs, the nails or screws must be removed. While the infection
is healing, which takes about ten days, the fracture cannot be
set by means of an operation. The consequence is that during
this period the patient must be immobilized.
In addition to this risk of infection with customary
external setting devices, another disadvantage is becoming more
apparent. Measurements with doppler lasers, with which the blood
circulation in the bone can be clinically measured, have shown
that inserting nails or screws causes a considerable disruption
in the circulation in the bone. This means that in inserting
external fixation devices, nails, or screws, the surgeon is
already creating the next stage in the treatment (including the
risk of Pintrak infection and ten-day immobilization of the
patient for change of procedure). This has negative effects
when, because of time factors, or for treatment of damage to soft
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~tissue, the external setting device is temporarily used. In the
case of a catastrophe, such as an airplane crash or railroad
accident, injured persons must be treated as quickly as possible.
For such cases the external setting device is excellent. Here
too, however, the above-described problems will arise.
summarY of the Invention
The foregoing problems are in large measure overcome by the
present invention which comprises a bone pincer, comprising a
pair of jaws, a pair of legs which may act as handles and a hinge
joining the jaws which can be locked with the jaws in various
positions. The pincers can be removably attached to a bone with
little penetration of the bone, thus minimizing infection. A
plurality of the pincers, attached to a bone, may be connected to
support rods to provide a stable but easily removable external
fixation device.
Brief Description of the Drawings
The invention will be further described with reference to
the accompanying drawings, in which:
Fig. 1 is a top plan view of an example of pincers according
to the invention;
Fig. 2 is a bottom plan view of the pincers of Fig. l;
Fig. 3 is a perspective view of the pincers of Fig. 1;
Fig. 4 is an exploded view of the pincers of Fig. l; and
Fig. 5 is a perspective view of an external fixation device
using a plurality of the pincers of Fig. 1.
Detailed Description of the Invention 2 0 4 2 5 7 3
The bone gripping pincers illustrated from above and
from below in Figs. 1 and 2 consists essentially of a hinge
or swivel joint 1, a minimum of two jaws 2,3 and a minimum
of two legs 4,5, which serve as handles. The swivel joint 1
can be operated by manipulation of legs 4,5, whereby jaws
2,3 move toward each other. The two jaws 2,3, bowed like
jawbones, may be given a spring-like resilience by narrowing
cross-sections 15 or 16, so that when the surgeon grips a
bone fragment a manually determined spring force can be
exerted. The free ends of the two jaws 2,3 are sharply
pointed, in order to guarantee a secure gripping of the bone
fragments.
After the desired bone fragment has been gripped, the
swivel joint 1 or its two components, to wit, pin component
10 and bore component 20, can be locked against each other
by simple tightening of the nut 7, whereupon the spring
tension applied by the surgeon continues and prevents the
tension of the pincers from slackening. The swivel joint 1
can be unlocked by a simple unscrewing of the locking nut 7.
Once the bone gripping pincers has been fixed at the
desired position with the desired spring tension, the two
legs 4,5 can be removed from swivel joint 1. For this
purpose, as illustrated in Fig. 3, legs 4,5, are preferably
each equipped at the swivel joint end with a square boss 17
that fits into the corresponding, radially positioned
openings 18 (in the swivel bore element 20) and 19 (in
swivel pin component 10). This makes it possible to keep
the osteosynthetically effective portion of the pincers as
small as possible.
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As illustrated in Fig. 2, the pincers have a connection pin
9 which can be locked in any desired position by means of a
locking nut 8, and which pin is positioned in such manner so that
it can be rotated about axis 6 of the swivel pin component 10.
This connection pin 9 can be positioned before the operation or
during the operation, depending on space conditions. The
connection pin 9 makes it possible to connect an entire series of
bone gripping pincers together to create a larger assembly.
Connecting the pins 9 can be done in conventional manner with the
customary aides such as support rods and clamps, as in
conventional external fixation systems.
As illustrated in Fig. 4, in one preferred form the swivel
joint 1 consists of a pin joint with a pin component 10 and a
bore component element 20 for receiving pin component 10. The
two elements 10,20 have disc-shaped bases 21,22, each of which
bears one of the two jaws 2,3. The base 21 of the pin component
10 has an axially positioned cylindrical pin 6, each of the two
ends of which has a thread 23,24. The base 22 of bore component
element 20 has a central bore 24A, designed to receive the
cylindrical pin 6.
Each of the two disc-shaped bases 21,22 has two movement
stops (11,12; 13,14), offset concentrically against one another,
which limit the rotation of the two components 10,20 in clockwise
and counterclockwise directions.
So that the position of the pin component 10 can be fixed
opposite the bore component element 20 in such manner that it can
be released, in addition to locking nut 7 with its bore 26 there
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is a washer 27 between locking nut 7 and bore component element
20, which washer 27 has a hexagonal opening 28 at its center and
a concentrically positioned, radially grooved circular area 29 on
its underside. The base 22 of bore component element 20 has on
its top a radially grooved circular area 25 that corresponds to
the circular area 29 of washer 27. Lastly, that portion of
swivel pin 6 that is positioned at the level of washer 27 is
designed with a hexagonal cross-section 30, which allows washer
27 to rotate when pin 6 is rotated.
When the locking nut 7 is unscrewed, the two components 10
and 20 can move reciprocally (the two grooved circular rings
25,29 not being in contact with each other); whereas when the
locking nut 7 is screwed down the two surfaces 25 and 29 with
their ribbed structures are clamped together, so that the washer
27, and hence also the segment 30 of swivel pin 6, which sits
tight in the hexagonal opening 28, is locked with respect to the
bore component element 20.
. By means of a similar construction, it is possible to fix
the connection pin 9 in a radial position. For this purpose, the
connection pin 9 has a disc-shaped base 30A, which has an
annular, grooved zone 31 on its top surface, which zone 31
corresponds with a grooved circular area 32 on the underside of
the disc-shaped base 21 of pin component 10.
The disc-shaped base 30 has a centrally positioned bore 33,
which can accept the swivel pin 6. By means of the hexagonal nut
8, which has a central bore 34 with internal threading 35, the
connection pin 9 can be fixedly connected to the swivel pin 6,
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the internal threading 35 of bore 34 corresponding to the
external thread 24 of pin 6.
If the nut 8 is only partially screwed down on the thread
24, the connection pin 9 can, if desired, be rotated around pin
6; when the nut 8 is screwed tight, the two grooved circular
areas 31 and 32 dovetail, so that connection pin 9 can be locked
in any desired position.
As shown in Fig. 5, thanks to connection pin 9, it is
possible to connect two or more bone gripping pincers by means of
auxiliary elements (clamps, clips, etc.) to a support rod, to
achieve an extremely stable external fixation device. As shown
in Fig. 5, two pincers of the type described are connected via
their pins 9 and conventional clamps 41 to a support rod 40 on
either side of a fracture 43 in a bone 42.
From the foregoing description, it will be seen that using a
device according to the invention, instead of a screw or a nail,
the bone is held between the pointed jaws of the bone gripping
pincers. The advantage is that no hole need be drilled through
the bone, with the result that no heat necrosis is created by the
drill and there is minimal disruption of the circulation in the
bone. Several such plier-like bone gripping pincers can be
externally connected like screws or nails. The principal
indication of the bone gripping pincers according to the
invention is the temporary setting of open lower-leg fractures.
This means that they can be used merely for intra-operative
repositioning of the fracture, or they can be left on the bone,
after completed repositioning, until the soft parts have
~< ~042~7~
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completely healed. In both cases there can be a change of
procedure (e.g. marrow nailing) with the pincers left in place.
Leaving the pincers in place until the fracture has healed poses
no problem, though it is seldom appropriate because of the simple
possibility of a change of procedure. If a nPintrak infection"
occurs during the treatment period, it is merely superficial and
can be treated simply, since the bone under the tips of the bone
gripping pincers is vital.
The application of the bone gripping pincers according to
the invention is not limited merely to the classic ~external
fixation~. It can be used wherever a fracture must be
repositioned or a length of bone must be held.
An advantageous application of the bone gripping pincers
according to the invention further consists in the temporary
locking of a marrow nail, since the application of the bone
gripping pincers according to the invention, compared to screws,
is easier and faster and can be done without the use of x-rays.
The same applies in indirect repositioning with a
distractor. In place of buttressing screws the bone gripping
pincers according to the invention can be used, in order to avoid
hold drilling in the bone that is not necessary for treatment of
the fracture.
The pincers of the invention offers enormous advantages in
the treatment of persons injured in war or in catastrophes, where
fractures must be treated without large-scale auxiliary
equipment, quickly, and in some cases by persons with minimal
training. In these situations, the bone gripping pincers
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20~-25~3
according to the invention offers much lower risk of infection,
and no additional instruments or machines are needed. Fractures
not treated adequately can be corrected re reset without
difficulty at a later date.
Local application of the bone gripping pincers according to
the invention depends on the structures of the soft parts (blood
vessels, nerves, etc.) that surround the bones. In the presence
of structures that are endangered, access to the bone, as when an
external setting agent is used, must be carefully prepared.
The design of the invention in the form of a pincers has
numerous advantages.
The bone gripping pincers according to the invention can be
handled by the surgeon like other pincers-type instruments. Thus
the surgeon is already familiar with such devices, and knows how
to determine the gripping power of the pincers. The properly
positioned application of a pincers is much easier than, for
example, the proper application of a clamp. The pincers jaws are
preferably constructed in such manner that they have a spring
quality. The advantage of this is that if the pincers jaws give
way or slip slightly on the bone, the pincers will not lose their
grip on the bone. ;
The pincers lock can be activated by a simple tightening of
a screw nut. The advantage of this is that after successful
attachment of the bone gripping pincers to the bone, the handle
can be removed, so that the external construction can be designed
as small as possible.
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The connection pin, which moves freely in one direction,
makes it possible to connect several individually positioned
pincers to a straight connection rod.
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