Note: Descriptions are shown in the official language in which they were submitted.
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BACKGROUND OF THE INVENTION
The present invention pertains to an osteosynthesis
aid for bone fixation, particularly for application to pelvic-
bone structure.
German Patent No. 3,917,916 C1 discloses and
describes an external fixation device, particularly for
application to the pelvis. The device comprises two bone-pin
or screw-holding clamps, and these clamps are ball-joint
connected and selectively clamped to a central body. The
central body consists of two pivotally connected elongate arms
each of which has telescopically guided parts which provide a
measure of arm-length adjustability. The telescopic
adjustments and the pivotal connection of the arms are both
releasably securable to hold given adjustment thereof.
The known device is rather expensive and has a
limited range of length adjustability, so that several
different sizes must be kept in stock in order to provide the
surgeon with the proper osteosynthesis aid for a specific case
of use.
BRIEF STATEMENT OF THE INVENTION
The principal object of the invention is to provide
an osteosynthesis aid for use in connection with pelvic bones,
offering a great range of possible releasably locked
adjustment but of simple low-cost construction; and it is also
an object to provide in such a simple device for the
previously available feature of selectively adjusted
articulation. A specific object is to provide improved
releasably lockable means for positive retention of any
desired adjustment.
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The invention provides an osteosynthesis aid for
bone fixation, particularly for application to the pelvis,
comprising a central multi-part body of variable length
between spaced ends of said body, first and second bone-pin or
screw clamps having a releasably lockable ball-joint
connection to the respective ends of said body, said body
comprising two arm or link members each of which has an
elongate slot and a lock bolt through the slot of each of said
arm or link members, for releasably locked retention of said
link members in a selected position of adjusted angular
relation and overall length, wherein said lock bolt comprises
a shank of length to exceed passage through the slot of each
of two arm members to be connected, a head at one end of the
shank and of diametral extent to span the width of the arm
member adjacent thereto, said shank having a cylindrical
portion for at least a proximal region adjacent said head,
with the cylindrical portion extending through the thickness
of the arm member adjacent said head, said shank being
enlarged and configured at its distal end for keying
engagement with at least a portion of the slot of the other
arm member and distally projecting beyond said other arm
member, and locking means including rotatable eccentric means
on an axis transverse to said shank and reacting between the
distal projection of said shank and said other arm member for
eccentrically driven development of axial compression of said
arm members between said head and said eccentric.
The invention provides an osteosynthesis aid for
bone fixation, particularly for application to the pelvis,
comprising a central multi-part body of variable length
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between spaced ends of said body, first and second bone-pin or
screw clamps having a releasably lockable ball-joint
connection to the respective ends of said body, said body
comprising two arm or link members each of which has an
elongate slot, and a lock bolt through the slot of each of
said arm or link members, for releasably locked retention of
said link members in a selected position of adjusted angular
relation and overall length, wherein said lock bolt comprises
first and second slide members each of which is configured for
non-rotatable but longitudinally slidable engagement with and
along one to the exclusion of the other of said arm members,
two disc members having confronting complimentary pluralities
of axially engageable and angularly distributed tooth
formations, means extending through the slots of both arm
members for keying one of said disc members exclusively to one
of said slide members, means keying the other disc member to
the other of said slide members, and a threaded bolt having
headed engagement to one of said slide members and passing
through aligned apertures in said discs and having threaded
engagement exclusively with a part of the other of said slide
members.
The invention provides an osteosynthesis aid for
bone fixation, particularly for application to the pelvis,
comprising a central multi-part body of variable length
between spaced ends of said body, first and second bone-pin or
screw clamps having a releasably lockable ball-joint
connection to the respective ends of said body, said body
comprising two arm or link members each of which has an
elongate slot, and a lock bolt through the slot of each of
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said arm or link members, for releasably locked retention of
said link members in a selected position of adjusted angular
relation and overall length, wherein said lock bolt comprises
first and second slide members each of which is configured for
non-rotatable but longitudinally slidable engagement with and
along one to the exclusion of the other of said arm members,
two disc members having confronting complimentary pluralities
of axially engageable and angularly distributed tooth
formations, means extending through the slots of both arm
members for keying one of said disc members exclusively to one
of said slide members, means keying the other disc member to
the other of said slide members, and selectively operable
axially actuable clamping means having referencing engagement
to one of said slide members and axially engaged to the other
of said slide members via passage through aligned apertures in
said discs for releasably actuated lock up or free up of
toothed engagement of said disc members.
Each of the ball-joint equipped arms has a slot
which extends preferably over virtually the entire length of
the arm, into proximity with the associated bone-pin or screw
holding clamps, and the fixation of these holding clamps is
effected via lock-bolt connection of the arms. Thus, the arms
can be pushed together to a minimum overall length dimension,
wherein the fixation devices are in near-contact with each
other, and they can also be pulled apart to a maximum size
such that the lock bolt establishes a limit stop at the other
slot extremes. In this way, substantially greater changes in
length are possible than in the prior art, while at the same
time the entire device is of extremely economical construc-
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tion, so that a two-fold advantage is obtained, namely, on the
one hand, fewer individual parts are necessary and, on the
other hand, the manufacture of the devices is less expensive.
Furthermore, one lock-bolt setting serves to retain a length
adjustment and a selected pivoted or articulation-angle
setting of the slotted arms with respect to each other.
Various lock-bolt configurations are described.
DETAILED DESCRIPTION
Preferred embodiments of the invention will be
described in detail in conjunction with the accompanying
drawings, in which:
Fig. 1 is a partly exploded view in perspective of a
fixator device of the invention, featuring a first selectively
operable locking device;
Fig. 2 is a similar view of optional connection-link
components usable with the fixator of Fig. 1, with an exploded
showing of the locking device of Fig. l;
Fig. 3 is a perspective view of the complete
fixator, to show an assembly of the parts of Figs. 1 and 2;
Fig. 4 is a view similar to Fig. 1, to show a
different locking device;
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Fig. 5 is a view similar to Fig. 2, with an exploded
showing of the locking device of Fig. 4;
Fig. 5A is an exploded view of dissassembled elements
of one of the parts of Fig. 5;
Fig. 5B is a view similar to Fig. 5A to show a modified
construction;
Fig. 6 is another view similar to Fig. 1, to show
another 'different locking device; and
Fig. 7 is another view similar to Fig. 2, with an
exploded showing of the locking device of Fig. 6.
In Fig. 1, an osteosynthesis aid or external fixator
device is shown with two bone-pin or screw holding clamps 2,
3 of known construction, and ball joints 4 and 5, with
detachable securing devices 6 and 7 by which to establish
interconnection via a central body 1, with an adjustably
secured angular relation between the elongation axis of each
pin or screw holding clamp 2 (3) and the longitudinal axis
of the adjacent end of body 1.
The detachable securing devices 6 and 7 are also of
known construction, so that their further description is
unnecessary.
The central body 1 consists of two elongate arms or
links in the form of narrow rigid members, each having a
slot (10, 11) which extends over substantially the entire
length of each arm, one end of each arm being formed with
part of an associated detachable securing device (6, 7) and
the other end of each arm being closed around the end of its
slot (10, 11). When arms 8, 9 are caused to intersect one
above the other as shown in Fig. 1, the respective slots
(10, 11) establish adjustable passage for the bolt 12 of a
lock-bolt mechanism, consisting of a machine bolt 12 and a
nut 14, preferably with interposed friction or lock washers
13 at seating bolt-head and nut engagement with the
respective arms 8, 9.
It can be seen that the pin or screw holding clamps 2
and 3 and the securing devices 6 and 7 can now be adjusted
to such proximity that the securing devices 6 and 7
practically touch each other and that, on the other hand,
these structural parts can be pulled apart to such an extent
that the lock bolt 12 passes through the extreme ends of
slots 10, 11, i.e., at the ends' most remote from securing
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devices 6 and 7. Also, upon tightening the bolt to the nut,
via the lock washers as described, not only is the selected
length secured (as between the ball joints 4, 5) but so also
is the selected angular relation between arms 8 and 9.
For even greater spacing of the locations of bone-pin
or screw clamping, the described fixator device of Fig. 1 is
part of a kit which additionally includes the parts of
Fig. 2, namely, an elongate link,.member 15 having a slot 17
extending substantially the full longitudinal extent of link
member 15, as well as an additional lock-bolt mechanism 16,
identical to that at 12 in Fig. 1. Fig. 3 shows an
interconnected use of the parts of Figs. 1 and 2, with the
selective availability of bone-anchorage points (via holding
clamps 2, 3) at extended spacing and bowed interconnection,
so that a fixation of pelvis regions can be effected even
for a patient with a large abdomen.
Merely for the sake of completeness, it is pointed out
that the fixing of the pin or screw holding clamps (2, 3) is
preferably established between the upper and the lower
anterior iliac spine or iliac crest.
Figs. 4 and 5 show adjustably linked structures as in
Figa. 1 and 2, except for the use of a different locking
means 20 to retain an adjusted setting, as to length and as
to angle between thus-connected members.
The lock-bolt mechanism 20 is seen in Figs. 5 and 5A to
comprise four parts wherein wrenched actuation of an
eccentric surface releasably sets the mechanism. The four
parts are (i) a headed pin assembly of two parts, namely, a
disc or head part 21, and a cylindrical shank portion 23
with an enlarged distal end 22 of generally rectangular
section, featuring a transverse bore 24 through the
thickness of said section; (ii) a circular clamp seat or
washer 27 featuring a bore configured for non-rotatable but
axially guided reception of the generally rectangular
section of the distal end 22 of the headed pin, and also
featuring like cylindrically arcuate bearing grooves on
opposite sides of the width dimension of the bore 24 of
distal end 22; and (iii) a transverse eccentric-locking pin
25 having spaced cylindrical bearings sized to pass through
the transverse bore 24 of the headed pin 21 and to derive
rotational support from the bearing grooves of the clamp
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seat or washer 27, with the eccentric formation 26 of pin 25
located between the spaced cylindrical bearings.
More specifically, the width dimension of the enlarged
distal end 22 of pin 21 is such as to permit slidable
insertion through the longitudinal slots of either of two
link members to be clamped, and~a generally rectangular
central opening in washer 27 will also be seen to
accommodate keyed insertion of distal end 22.
The effective longitudinal length of the cylindrical
shank portion 23 should be such as to assure that the
enlarged distal end 22 will engage the longitudinal slot of
one to the exclusion of the other of the link members to be
clamped, thereby permitting free link-member articulation
prior to clamping. As seen in Fig. 5A, the cylindrical
shank portion 23 has a lower end adapted for threaded
engagement to a tapped central bore of the head part 21; in
initial but incomplete assembly of shank 23 to head part 21,
the threaded engagement is to a point short of final or
fully-threaded engagement, substantially to the axial extent
of the throw of the eccentric. Clamped assembly is
completed by inserting the eccentric-locking pin 25 through
the transverse bore 24, with the spaced bearings of pin 25
nested in the spaced bearing grooves of washer 27, and with
the eccentric of pin 25 displaced maximally in the direction
of the loosely threaded engagement of shank 23 to the head
or disc part 21. In this condition, the parts will be
understood to be loosely assembled, permitting slot-
positioning selection and angular adjustment of the involved
link members. Thereafter, the threaded engagement is
advanced to completion and is preferably retained, as by
suitable set-screw means, suggested at 28, whereby the
clamping action may be releasably established by wrenched
rotation of pin 25, to cause its eccentric surface to jam
the parts via eccentric action on the transverse bore 24.
In the modification of Fig. 58, parts are as described
for Fig. 5A except that the cylindrical shank portion 23' is
sized for slidable fit to the smooth central bore of the
head or disc part 21'. The shank portion 23' has a
transverse-pin bore which will register with a transverse-
pin bore in disc part 21', once the eccentric region of
locking pin 25 is correctly positioned in the transverse
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bore 24. At that time, a transverse pin 28' driven through
the aligned transverse bores of disc part 21' and shank
portion 23' will retain the parts in readiness for
releasable clamping of the involved link members, via
wrench-driven rotation of the eccentric-locking pin 25.
In the embodiment of Figs. 6 and 7, the lock-bolt
assembly 30 involves six parts, in addition to the two link
members 8, 9 which are to be adjustably set and clamped for
angular relation and for span between their respective ball-
joint centers at 4 and 5. In Fig. 7, these individual parts
are:
(i) a lower slide member 31, shown as a channel
with side plates for guidance along outer sides of
one to the exclusion of the other of the two link
members to be clamped; and with an elongate
central pedestal 32 rising from the channel base
for further stabilization of guidance solely in
the elongate slot of said one link member. An
upstanding column 33 of hexagonal section (and
having a tapped central bore) rises integrally
from pedestal 32 and is of sufficient length to
extend through the combined thickness of the two
link members to be clamped, and to extend a short
distance beyond, for a keying purpose which will
be explained;
(ii) a pair of locking disc members 37, 36 having
confronting faces with complimentary plural tooth
formations in angularly distributed array in order
to physically lock the angular relation of disc
members 37, 36 when axially clamped together. In
Fig. 7, the lower one (37) of these disc members
will be understood to have a flat annular surface
sized for clamped seating on both legs of the
upper one of the involved two link members to be
clamped, as in the case of link member 9 of Fig.
6; this disc member 37 also has a central bore of
hexagonal section to engage column 33 and to key
the same against rotation with respect to the
lower slide 31 and, hence, also with respect to
the lower link member (e.g., member 8) to be
clamped. The upper one (36) of the toothed disc
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members has a flat upper surface from which a
central projection of square section rises to an
extent sufficient to establish its keyed relation
with an upper slide member 35.
(iii) the upper slide member 35 is also shown as a
channel with side plates, for guidance solely
along outer sides of the other link member (e. g.,
upper link member 9 in Fig. 6). The base of the
channel of slide member 35 has a central opening
of square shape to receive the square projection
of the upper one (36) of the toothed discs,
thereby completing the keyed relation noted above
for these two parts.
(iv) a wrenchable bolt 34 and seating washer 38
complete the recital of parts, it being noted that
upon assembly of the described parts of lock bolt
30, the shank of bolt 34 passes freely through
central openings in washer 38, slide 35, and the
toothed discs 36, 37, with threaded engagement
solely to the tapped bore of column 32 of the
lower slide 32.
Thus, for the lock-bolt configuration of Fig. 7 in use
at 30, in the combination shown in Fig. 6, it is possible to
obtain any desired angular adjustment of link members 8, 9,
within the number of tooth-engageable relations as between
discs 36, 37. And, whatever the selected angular
relationship, a wrenched setting of bolt 35 engagement to
the tapped bore of slide 31, will establish an absolute lock
of the involved link members. The same availability of a
locked-up angular relation is also achievable whenever link
member 15 is selected for interconnection to the respective
ball-jc,int equipped link members 8, 9, wherein lock bolts 30
are used in replacement of the locking bolts 12 and 16 of
Fig. 3.
It will be understood that, for convenience, the
expression "lock bolt" or "lock-bolt mechanism" has been
used in connection with devices 20 (Fig. 4) and 30 (Fig. 6),
even though they are not conventional nut and bolt
' configurations. And it will be noted that, for all disclosed
embodiments, the particularly involved "lock-bolt mechanism"
incorporates its own means of locked engagement to each of
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the two link members thereby secured to each other. This
result is achieved without any special upper or lower
surface roughening of either of the arm members that are
lock-bolt secured, so that the surfaces of all arm members
(8, 9, 15) may be and preferably are of smooth finish
throughout. And in the case of means 30 (Fig. 6), the
angularly adjusted lock-up establishes a positively keyed
relation of the involved arm members.
