Note: Descriptions are shown in the official language in which they were submitted.
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Pfeil and Veith -- 0752-3
UNILATERAL) EXTENSIBLE, EXTERNAL TENSIONING DEVICE
FOR TREATING BONE DISEASES.
s The invention concerns a unilateral, extensible, external tensioning device
far treating bone diseases.
Such an orthopedic device is described in the US patent 4,312,336 for the
axial, external fixation of bones or bone fragments.
Already unilateral screw affixing device for treating bone diseases of the
,o extremities have been described several times. The multitude of different
bone diseases
sets different requirements on external fixation. Accordingly a kit system
meeting the
diverse requirements shall be advantageous. The apparatus described herein
meets many
demands in external fixation. It also makes possible taking care of double
stage fractures,
mono- and bi-focal extension) also motor-driven extension and callus
stimulation. As
,s regards pseudo-arthrosis, it allows fragment displacement. Also the
described apparatus
permits continuous change in all directions of motion.
Comparable orthopedic devices, for instance as described in the German
patent 3,543,402 (Orthofix), are only able to take care of part of the above
indications
and especially it has been impossible heretofore to take care of double-stage
fractures)
zo bifocal extensions and continuous changes or motor-driven extensions and
fragment
shifting using the Monofixateur (single affixing means). As regards these
indications,
affixing means heretofore were required) which are difficult to put in place
by operation
and which perforate the skin from several directions. The previously available
orthopedic
devices suffered from the drawback that depending on the location of the
indication) a
zs completely new device had to be used, because illustratively it was
impossible by means
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of one device to carry out both fracture care and extension. The previous
systems
moreover incurred the drawback that different parts had to be mounted on the
affixing
means during treatment, and as a consequence frequently parts of this affixing
means
were lost and unnecessary additional costs were borne.
Accordingly it is the object of the present invention to create a unilaterally
extensible external tensioning device for treating bone diseases) the
pertinent bone
segments being fixed in position relative to each other) tensioned, shifted in
controlled
manner and be dynamizcd in guided, dynamic, irrotational manner by means of
bone
screws held in clamping jaws.
~o This problem is solved by the invention in that at least one piston is
mounted in extensible manner on each side of a tubular central part) various
link means
being attachable in rotatable manner to the outer ends of the inner pistons.
The scope of the invention is such as to provide both two pistons only in
the central part on one hand, and two further telescoping pistons inside the
above pistons
is on the other. The links are always mounted to the innermost piston.
The orthopedic device of the invention makes it possible on account of the
special double telescoping and the high strength of the articulating links
relative to flexure
to use only one type of affixing device for the lower extremity and a further
type of
affixing device for the upper one. This means that fewer types of bone-
fixation devices
2o need be stored in an orthopedic or emergency clinic, while on the other
hand the scope
of indications of this device is much wide than for comparable single fixation
means. The
orthopedic device of the invention is designed in such a way that before
treatment and
with corresponding problem definition,various parts are apposed in the manner
of the kit
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system. Therefore no part shall be removed during treatment, and there is no
danger of
losing any.
The advantages made possible in this manner can be summarized as
follows:
s By means of one size each for the lower and upper extremities, the
orthopedic device described herein makes it possible to treat all bone
diseases wherein
the indication points to a fixation device. No parts are screwed on or off the
orthopedic
device during treatment and therefore there is no danger of Losing any during
it. Handling
is technically comprehensible and simple. Nevertheless a large scope of
indications is
io covered by the orthopedic device.
Especially preferred embodiments of the unilateral, extensible, external
tensioning device of the invention are described in the claims.
A specific length of the central part and the two pistons can be set by
means of the telescoping pistons. Various links may be fastened by a clamping
pin to the
,s pistons, and bone screw clamping jaws in turn may be affixed to said pin.
Especially
preferred designs are provided for the links, for instance an articulating
joint plugged by
means of the clamping pin onto the piston end and allowing spatial adjustment
and
fixation of a screwed-on bone screw clamping jaw.
These bone screw clamping jaws can be screwed-on longitudinally and/or
2o transversely (so-called T jaws).
Again a rigid intermediate part is preferentially provided as a link which
also can be plugged by a clamping pin onto the piston end, comprising an
inside thread
opposite the said piston end to screw-on a bone screw clamping jaw.
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Also, a so-called switch is provided as a link) which implements by means
of a self-locking worm drive the defined pivoting motion of the platform
mounted to said
worm.
Further it is possible to use a hinge means to be clamped at an arbitrary
s site as a link and which upon release of the clamping serves to dynamize
joints in the
plane of the hinge rotation.
A periodic .in-and-out motion of the piston through the intermediary of the
Schanz screws causes growing micro-motion of the fracture site and thereby
callus
stimulation; a variety of embodiments are feasible in this respect.
Illustratively a flange-
~o mounted step motor may be driven in such a way that the adjustment nut
shall be rotated
counterclockwise at the desired rate. The piston in such a case also would
move in and
out and the fracture site thereby would experience a growing micro-motion.
As described, the rotating adjustment nuts control the piston-setting relative
to the central part. In principle it is possible to provide an adjustment nut
detachable
,s from the central part and remaining on the piston in order achieve quick
setting to match
the anatomical particulars or for purposes of dynamization.
In principle, an adjustment nut detachable from the central part can be
provided, which remains on the piston to allow rapid adjustment to match
anatomical
particulars or to allow dynamization.
zo Next the invention shall be elucidated in relation to the attached
drawings.
Fig. 1 shows the central part and the two pistons of the external tensioning
device in partly sectioned form,
Fig. 2 is the elevation of the various parts of the external tensioning device
in partly sectioned form,
5
Fig. 3 is a sideview in partial sectioned form of the parts of Fig. 2)
Fig. 4 is a rigid intermediate part,
Fig, S is a clamping hinge,
Fig. 6 is the section of the adjustment nut 8 and the ring 12 of Fig. 8,
s Fig. 7 is the cross-section of the adjustment nut 8 and the ring 12 shown in
Fig. 6,
Fig. 8 is the partially sectioned elevation of a further central part)
Fig. 9 is the topview of the central part shown in Fig. 1, with retracted
piston 3) and '
io Fig. 10 is the section I-I of Fig. 9.
Essentially Fig. 1 shows the central part 1 and the pistons 3 and 4 of the
external tensioning device. The tubular central part 1 comprises a spline
socket 2 wherein
is guided the hallow piston 3 which for that purpose is provided with a
matching spline
or key key toothing 7 over its entire length. The central part 1 and the
extensible piston
is 3 thereby are secured against rotation on one hand while on the other free
axial motion
of the two parts is ensured. This is especially significant in dynamization.
In order to
clarify and discuss the individual parts, they are shown in exploded view in
Fig: i, but it
is clear from the description that both the piston 3 the piston 4 act in
concert with the
central part 1.
zo The solid piston 4 opposite piston 3 also is provided over its entire
length
with the spline or key serration 7. It is guided by a correspondingly inside-
serrated bush
fitted into the tubular end of the central part 1.
Both pistons 3 and 4 may be telescoped into the central part 1) ie into each
other (4 into 3). The maximum length possible is achieved by extending both
pistons 3
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and 4) the central part 1 being extended almost by a factor of three. The
required overlap
of the spline at both ends of the central part reduces that length, being
necessary to
secure axial guidance and force transmission.
To allow a specific extension or shortening of the external tensionng device
s even when it is subjected to forces, both pistons 3, 4 comprise threads 51)
52 resp. which
preferably shall be of the same pitch. The adjustment nut 74, 75 fitted with
the matching
inside thread allows axially displacing the piston 3,4 relative to the central
part 1. The
displaceability of the two pistons 3) 4 is independent of that of the other.
The two adjustment nuts 74 and 75 are identical except for the different
~o inside threads corresponding to the different piston cross-sections. The
operation of these
adjustment nuts 74, 75 is elucidated by Figs. 9) 10. They are guided by means
of one or
more slide blocks.
The adjustment nuts 74, 75 are linked in rotatable manner to the central
part 1. By rotating the adjustment nut 74) 75, the resp. piston 3,4 shall
retract or advance.
,s Fig. 2 shows the various parts of the external tightening device, partly in
section, in the dismantled state.
Fig. 3 shows the parts of Fig. 2 in sideview. Figs. 2 and 3 are discussed
below. Figs. 4 and 5 show further possible links for the external tensioning
device.
As shown by Fig. 1, the borehole 14,15 is located resp. at the outer end of
xo the piston 3,4 and the arbitrary link means shown in Figs. 2, 3, 4 and 5
may be installed
in said borehole using a pin i6.
The pin 16 comprises an annular recess 17 with bevelled sides, and this
recess can be entered by correspondingly bevelled set screws 18, 19 resp.
(Fig. 1). The
moment the screw 18, 19 slightly enters the annular recess 17 of the pin 16
inserted into
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the borehole 14, 15) said pin no longer can slip away, while free rotation on
the other
hand is preserved. The end face of the piston 3,4 is provided with a radial
knurling 20)
21. A corresponding knurling 22) 23 is present at the lower side of the link
means. When
the set screw 18, 19 is turned in all the way) the bevels on the screws and on
the recess
s fully lighten the additional element (link) against the end face of the
piston, the radial
knurling or serration preventing mutual rotation of the two parts.
The uppermost part shown in Figs. 2 and 3 is a bone screw clamping jaw
61 which can be affixed by an axial set screw 26 to the lower link means. ie
to the link
shown in Figs. 4 and S. To prevent the jaw 61 from rotating relative the
particular added
,o part, a longitudinal groove 31 is present at the lower side in the area of
the screw and is
entered by a matching longitudinal key 32 (or 40, S0, 68) at the communicating
side of
the link means. The clamping jaw 61 is divided centrally and longitudinally
above the
screw head. It is fitted on both part surfaces with semi-round grooves
transverse to the
center axis of the jaw 61 and serving to receive the bone screws 27 and 28.
These bone
~s screws are tightened by screwing-on the upper part.
The lowermost portion of Figs. 2 and 3 shows the described clamping jaw
61 having been rotated by 90° so that the linkage plane of the two bone
screws is
perpendicular to the central axis of the external tensioning device. In this
case the
screwing of the clamping jaw 61 to the particular link takes place by means of
a hexagon
zo socket screw. Again the clamping site is provided with a groove 30 to
prevent rotation.
Below the clamping jaw 61 shown as the uppermost component in Figs. 2
and 3, there is the switch 62 acting as a link. The defined rotation of the
platform 35 is
achieved by said switch by means of a self locking worm drive Consisting of
the worm
shaft 33 and a worm gear 34. Illustratively the clamping jaw 61 may be screwed
in
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rotation-secure manner on this platform 35. The worm is driven using a
hexagonal socket
at its end.
Fig. 2 shows a second component in its lower part in the form of an
articulating link 59 which basically is a universal joint that) together with
the rotatability
s of the clamping pin 16, allows pivoting the screw-tightened clamping jaws
61. A partly
slotted circular segment 36 encloses the cylindrical inner part 37. The
through-bolt 38
guided in the slot of the circular segment 36 passes through the inner part 37
which can
rotate by a specified angle about its axis of rotation. Clamping of the inner
part 37 takes
place by means of a hexagonal socket screw but the nut 39 cannot rotate
relative to its
1o support because of its shape matching the convex outside of the circular
segment 36 and
a key entering the groove. As a result, the clamping screw 38 can be tightened
using only
one key and without having to hold another part in place.
A square bar 40 pivotable to both sides in a plane perpendicular to the
cylinder axis is present in a slotted clearance of the inner element 37 and
also may be
is clamped in place by the through-bolt 38. To improve security against
rotation, a radial
knurling is provided in the region of the bolt borehole 38 not only on both
sides of the
square bar but also on the insides of the cylindrical clearance 37 facing it.
The square
bar 40 comprises an inside thread so that by means of a screw the clamping jaw
61 may
be tightened to it.
The central part of the external tensioning device shown by Figs. 2 and 3
displays the bone-segment fixation device 63. A ring 42 matching the outside
diameter
of the central part 1 upon removal of the adjustment nut is mounted at an
arbitrary
location on the central part 1. A cylindrical element 43 with inside thread is
present at
the circumference. A platform 44 shaped in relation to the periphery of the
central part
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1 encloses the element 43 and comprises a clearance in the area of the ring 42
below it.
If now pressure is exerted by the screw 45 through the upper clamping jaw 46
and the
bone screws 64 and 65 in-between on the platform 44) then this platform shall
be
tightened at the desired location to the central part 1) In this case the
clamping jaw 46
s is rotatable through a specific angular range about the axis of the screw 45
, making
possible the alignment of the bone screws 64 and 65 holding the bone segment.
To
prevent undesired rotation, a radial serration is present at the lower side of
the clamping
jaw 46 and on its rest 43, which will mutually engage during clamping.
Fig. 4 shows another link which may be used in lieu of the intermediate part
62 or 59 of Figs. 2 and 3. The rigid intermediate part 66 shown in Fig. 4
comprises the
above described pin 16 acting as the clamping element. Opposite this pin 16
there are
the inside thread 25 and the key SO with which the described bone screw
clamping jaw
61 can be screwed-on in irrotational manner. This intermediate part 66 also
comprises
the knurling 23.
,s Fig. 5 shows a clampable hinge joint 67. This hinge joint 67 can be clamped
anywhere and upon clamping release serves to dynamize joints in the plane of
the hinge
motion.
The pivoting square bar 68 is rigidly joined to the pivot bolt 69 supported
in an element 70 that) in U-shaped manner, encloses the square bar 68., The
end of the
2o pivot bolt 69 projecting beyond the element 70 is threaded and is milled
flat on two
mutually opposite sides. The disk 71 is radially serrated on one side and is
mounted in
irrotational mariner, by means of a borehole matching the bolt cross-section,
on this pivot
bolt 69.
so
A spiral spring 73 wound between the element 70 and the disk 71 around
the pivot bolt 69 keeps the disk 71 spaced from the clement 70. Too, the
element 70 is
provided with a matching radial serration on the side facing this disk 71. Tf
now the disk
71 is pressed by the nut 72 against the serration, the entire hinge 67 will be
locked. A
s seat and a pin 16 are provided in the square bar 68 and the element 70 resp.
for the pin
connection that was described above in relation to Figs. 2 and 3.
As regards the partly sectional elevation of the central part 1 shown in Fig.
8, the adjustment nut 8 or 9 always is located at the end of the central part.
The
operation of these nuts 8 and 9 now will be elucidated in relation to Figs. 6)
7 atad 8.
so The correspondingly internally serrated bush 5 fitted into the tubular end
of the central part 1 serves to guide the solid piston -- which is omitted
from Fig. 8 but
corresponds to the piston 4 shown in Fig. 1. This bush 5 is secured by a set
screw 5
which, when being turned in the continuous inner thread borehole, can be made
to
project from the inside of the bush S and thereby can additionally clamp the
solid piston
ss 4.
The two adjustment nuts 8 and 9 comprise inside threads corresponding
to the threads 51 and 52 resp. present on the raised outer parts of the
pistons 3 and 4.
These adjustment nuts 8 and 9 allow axially displacing the pistons 3 and 4
relative to the
central part 1.
zo The two adjustment nuts 8 and 9 are identical except for the inside threads
formed for the different piston cross~sections. The nuts 8 and 9 enclose like
collars the
particular ends of the central part 1. These collars comprise boreholes 10 on
their
peripheries to receive balls 60; the boreholes 10 taper inward and allow the
balls to
partly project but prevent them from dropping out. '
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A semi-annular recess 11 at the level of the central plane of the balls 60
revolves along the circumference of both ends of the central part. The
adjustment nut
8 or 9 accordingly is rotatably connected to the central part 1. The receding
of the balls
60 prevents a ring 12, which is enclosed in freely rotatable manner by a split
ring, and
s which encloses the collar (adjustment nut 8 or 9). When the adjustment nut 8
or 9 is
rotated) the particular piston 3 or 4 appropriately advances or retracts.
For purposes of instrumentation or dynamization, it is desirable to loosen
the axial connection provided by the adjustment nut 8 or 9 between the piston
3 or 4
resp, and the central part 1. For that purpose the ring 12 of Figs. 6 and 7 is
provided at
1o its rim with a number of comically, outwardly tapering boreholes 53
matching the number
of balls and their positions and which, while offset circumferentially
equidistantly, shall
be masked upon rotation of the ring 12 with the boreholes 10 in the collar
part
(adjustment nut 8 or 9)) whereby the balls 60 may recede centrifugally without
being able
to drop out. Figs. 6 and 7 show the adjustment nut 8. However the adjustment
nut 9 is
1s of similar design and cooperates with a corresponding ring 12.
A screw 54 located at the level of the central plane of the balls in the
collar
on account of a corresponding clearance 56 in the circumference of the ring 12
allows
restriction the path and stopping the rotating ring 12. A radial set screw SS
present in
the thread plane of the adjustment nut 8 or 9 allows affixing the nut 8 or 9
detached from
2o the central part 1 at an arbitrary location of the piston 3 or 4. This
permits limited
dynamization of the bone segment supported by the external tensioning device.
In
relation to the selected axial segment) only deforming forces of defined
magnitude shall
be applied to the bone.
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In lieu of the just above described adjustment nuts 8 and 9 of Fig. 8, the
Fig. 1 shows the adjustment nuts 74 and 75 of which the operation shall now be
elucidated in relation to Figs. 1, 9 and 10. Fig. 9 is the topview of the
central part 1 with
retracted piston 3, and shows the adjustment nut 74. The adjustment 75
operates
s similarly and shall not be described in detail hereafter.
In this embodiment mode) one or several slide blocks 76 may move in at
least one or several key grooves on the piston 3. On account of a recess in
the form of
an annular arc of circle in the vicinity of the thread of the adjustment nut
74) the slide
block 76 is constrained to follow Lhe axial motion of the adjustment nut 74 on
the piston
io 3. The rim projecting on the central side of the slide block 76 also
comprises a recess.
This latter recess is entered by a radially mounted screw 77 of the central
part 1, and
thereby this screw hampers the slide block 76 regarding axial displacement.
Accordingly rotation of the adjustment nut 74 results in an appropriate
extension or retraction of the pertinent piston 3. If the screw is 77 is
tightened-in hard,
is then it shall press the slide block 76 firmly into the key°s groove
and thereby the piston
3 is prevented from moving axially) ie the adjustment nut 74 is prevented from
rotating.
If the screw ?7 in the central part 1 is turned out, then the pertinent piston
3 can be
pulled out of the central part 1 in order to effect a quick adjustment.
