U.S. patent application number 11/094344 was filed with the patent office on 2005-08-18 for osteosynthetic bone plate.
This patent application is currently assigned to Medartis AG. Invention is credited to Joos, Ulrich, Pfefferle, Joachim.
Application Number | 20050182408 11/094344 |
Document ID | / |
Family ID | 8073857 |
Filed Date | 2005-08-18 |
United States Patent
Application |
20050182408 |
Kind Code |
A1 |
Pfefferle, Joachim ; et
al. |
August 18, 2005 |
Osteosynthetic bone plate
Abstract
The invention relates to an osteosynthetic bone plate which has
elongated compression cavities containing eccentric
countersinkings. The plate comprises a longitudinal axis (X), a
transverse axis (Y), a plate upper side and a plate lower side,
whereby the latter is placed facing the bone fragments. The bone
plate also comprises a compression element consisting of two plate
braces which run substantially parallel to the longitudinal axis.
Both plate braces are linked together by bridging struts which
intersect the longitudinal axis. A plate brace has an eyelet on at
least one of the outer sides of the compression element. Additional
eyelets can be positioned in front of this eyelet. A compression
cavity is situated in each of said eyelets and a connecting strut
which intersects the transverse axis, extends between the eyelets
which are located on each plate brace.
Inventors: |
Pfefferle, Joachim;
(Munstertal, DE) ; Joos, Ulrich; (Munster,
DE) |
Correspondence
Address: |
LEYDIG VOIT & MAYER, LTD
700 THIRTEENTH ST. NW
SUITE 300
WASHINGTON
DC
20005-3960
US
|
Assignee: |
Medartis AG
Basel
CH
|
Family ID: |
8073857 |
Appl. No.: |
11/094344 |
Filed: |
March 31, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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11094344 |
Mar 31, 2005 |
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09979252 |
Nov 21, 2001 |
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09979252 |
Nov 21, 2001 |
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PCT/CH00/00299 |
May 25, 2000 |
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Current U.S.
Class: |
606/282 ;
606/285; 606/298 |
Current CPC
Class: |
A61B 17/8004 20130101;
A61B 17/8071 20130101; A61B 17/8085 20130101 |
Class at
Publication: |
606/069 |
International
Class: |
A61B 017/56 |
Foreign Application Data
Date |
Code |
Application Number |
May 25, 1999 |
DE |
299 09 025.6 |
Claims
1-8. (canceled)
9. An osteosynthetic bone plate for osteosynthetic compression of
bone fragments for the reconstruction of mandibular fractures, the
bone plate having a longitudinal axis and a transverse axis and
comprising: a plate upper side and a plate lower side for facing
toward the bone fragments; a compression part which has two plate
braces extending at least substantially parallel to the
longitudinal axis; bridging struts, which intersect the
longitudinal axis, connecting the two plate braces to one another,
each plate brace extending along a brace axis and having an eyelet
on at least one outer flank of the compression part; connecting
struts, which intersect the transverse axis, and extend between the
eyelets located on each plate brace; and oblong compression holes
having a longitudinal axis extending longitudinally along the brace
axis, and eccentric countersinks on the plate upper side for the
compression of the bone fragments, one of the compression holes
being situated in each of the eyelets, wherein the bone plate has a
thickness in the range from 0.5 mm to 1.5 mm.
10. The osteosynthetic bone plate as claimed in claim 9, wherein
two bridging struts extend symmetrically or asymmetrically with
respect to the transverse axis.
11. The osteosynthetic bone plate as claimed in claim 10, wherein
in a symmetrical arrangement of the bridging struts, the two
bridging struts extend laterally from an outer flank of one eyelet
on one plate brace to an outer flank of an opposite eyelet on the
other plate brace, or in an asymmetric arrangement of the bridging
struts, one bridging strut is offset toward the transverse axis and
extends from in front of one eyelet on one plate brace to in front
of the opposite eyelet on the other plate brace.
12. The osteosynthetic bone plate as claimed in claim 9, wherein
the bone plate is made of titanium.
13. The osteosynthetic bone plate as claimed in claim 9 wherein
bone screws inserted in the compression holes and in the fixation
holes provide monocortical engagement of the bone fragments.
Description
FIELD OF APPLICATION OF THE INVENTION
[0001] The present invention relates to an osteosynthetic bone
plate for the treatment of fractures, in particular for the
reconstruction of mandibular fractures. Such bone plates are fitted
intraoperatively in order to fix bone fragments joined together.
This may be necessary in osteosynthesis, following accidents in
which a bone has shattered into bone fragments, or in orthognathic,
maxillofacial treatment for surgical control of abnormal
positioning after an osteotomy and subsequent positional correction
of the bone fragments.
[0002] Such a bone plate is used principally to span and fix two
bone fragments together, one part of the bone plate in each case
being connected releasably to a bone fragment. In order to
establish the connection between the temporarily fitted bone plate
and the bone fragments, the bone plate has through-holes for the
insertion of bone screws which engage in the bone fragments. The
bone plates should be able to bend in order to correctly match the
bone geometry, but at the same time they must guaranatee sufficient
stability. These two requirements are in principle mutually
contradictory. Moreover, the bone plates should permit the buildup
of a pressure between the fragments, which is achieved by the
opposite arrangement of what are referred to as compression
holes.
PRIOR ART
[0003] DE 23 40 880 A1 discloses a solid linear bone plate which is
used for treating jaw fractures and which, spanning the fracture
site on the jaw bone, is screwed onto both of the bone fragments
that are to be joined together. In each half of the bone plate
there are two oblong holes oriented toward the plate center and
toward the fracture site. On the side directed away from the jaw
bone, the oblong holes have a countersink with a screw seat
configured as a beveled plane surface. At least one oblong hole per
half is inclined relative to the plate center. On the side directed
toward the jaw bone, the bone plate has a projecting notched strut
at the center. As a result of the arrangement of the oblong holes
and the beveled screw seats, the bone fragments are compressed
toward the fracture site when the inserted bone screws are
tightened; the pressure thus built up between the fragments results
in improved healing of the bone fracture.
[0004] However, because of its rigidity, this plate cannot readily
be adapted to the existing bone geometry. A rigid plate which
cannot be sufficiently bent to fit the jaw bone has the effect that
the bone fragment less anchored in the jaw is moved toward the
plate, and dislocations therefore occur. Even slight shifts in the
fracture area lead to the loss of the interfragment support, which
results in greater mobility within the fracture area. The simple
hole pattern on the plate additionally permits little variability
in terms of attachment to the bone fragments. For example, in
Prein, J. (editor): Manual of Internal Fixation in the
Cranio-Facial Skeleton, Springer-Verlag Berlin 1998, page 30,
straight or arcuate bone plates with compression holes for treating
fractured mandibles are shown which have a thickness of 1.65 mm or
2.0 mm, respectively, and are designed for bone screws with an
external thread diameter of 2.4 mm.
[0005] Thinner bone plates, for example with a thickness of between
0.5 mm and 0.9 mm, which can be bent more readily, are known in
craniofacial applications (cf. Prein, loc. cit., page 28).
Different configurations have been developed for this purpose, for
example the L-plate, Y-plate, T-plate, H-plate, X-plate, double
Y-plate or frame plate. Bone screws with an external thread
diameter of 1.0 mm to 2.0 mm are used for these. However, these
bone plates have no compression holes, but only simple cylindrical
screw holes with countersinks for partially receiving the screw
head. The provision of compression holes in these thinner plates
has been avoided because opinion hitherto held that a greater plate
thickness, for example 1.65 mm or 2.0 mm, was necessary for
building up a pressure between the fragments. In addition, with the
previously available production technology, it would have been
extremely complicated to work compression holes into thinner bone
plates, for example with the thickness of 1.0 mm.
OBJECT OF THE INVENTION
[0006] According to the prior art hitherto disclosed, no bone plate
has as yet been made available in which, even when absolutely
correctly applied, sufficient stability for unimpeded bone healing
is guaranteed and a pressure can be built up between the fragments
for the dynamic compression for improved bone fracture healing.
Particular requirements exist for example in respect of:
[0007] fractures of atrophic jaws;
[0008] unstable oblique fractures;
[0009] infected mandibular fractures;
[0010] unstable jaw angle fractures; and
[0011] mandibular fractures in noncooperative patients.
[0012] In view of the cited shortcomings of the bone plates known
to date, the object of the invention is to make available a bone
plate particularly for the treatment of mandibular fractures,
which, as a result of greater deformability, can be readily bent to
the respective contour of the bone fragments, but which
nevertheless guarantees a secure and positionally stable fixation
of the bone fragments. That is to say, the bone plate must be
easily deformable on the one hand and yet must have adequate
rigidity on the other. Moreover, the bone plate is to have
compression holes in order to be able to generate a pressure
between the fragments--in the sense of compression
osteosynthesis--for promoting the bone healing. Furthermore, the
bone plate to be produced must not pinch the nerve issuing at the
mandible and, in the event of comminuted fractures, small bone
fragments must also be able to be fixed individually on the bone
plate. Finally, the bone plate must be able to be applied using
conventional bone screws and must be able to be produced
economically in series.
OVERVIEW OF THE INVENTION
[0013] The osteosynthetic bone plate is used for the treatment of
fractures, in particular for the reconstruction of mandibular
fractures. The plate is intended to be screwed by means of
conventional bone screws, which have screw heads, onto the bone
fragments which are to be joined together in accordance with the
principle of compression osteosynthesis at a fracture line. The
plate has oblong compression holes with eccentric countersinks. A
longitudinal axis and a transverse axis, and also a plate upper
side and a plate lower side, the latter facing toward the bone
fragments, can be defined on the plate. The bone plate comprises a
compression part which has two plate braces extending at least
substantially parallel to the longitudinal axis. The two plate
braces are connected to one another by bridging struts which
intersect the longitudinal axis. A plate brace has an eyelet at
least on one of the outer flanks of the compression part, and
additional eyelets can be positioned in front of this eyelet. An
eyelet is preferably arranged on both outer flanks. A compression
hole is preferably situated in each of the eyelets, and a
connecting strut which intersects the transverse axis extends
between the eyelets located on each plate brace.
[0014] The following description refers to preferred illustrative
embodiments of the bone plate according to the invention: The
compression holes have, with their longitudinal extent, an
orientation in the direction of the brace axis or assume an angle
.noteq. 0.degree. in relation to the brace axis and have eccentric
countersinks on the plate upper side. In a continuation of the
compression part, attachment struts adjoin the eyelets and extend
on the brace axes. A disk-shaped plate member is situated at the
end of each of the attachment struts, and further plate members
connected by attachment struts can be positioned in front of said
plate member. A fixation hole for receiving a bone screw is in each
case provided in the plate members.
[0015] The connecting struts between the eyelets have a greater
width than the attachment struts leading to the plate members. The
fixation holes on the plate upper side have a countersink for
receiving the heads of the bone screws in a partially recessed
manner. Two bridging struts are preferably provided on the bone
plate and extend symmetrically or asymmetrically with respect to
the transverse axis. In the case of a symmetrical arrangement of
the bridging struts, both bridging struts extend laterally from the
outer flank of one eyelet on one brace axis to the outer flank of
the opposite eyelet on the other brace axis. In the case of an
asymmetric arrangement of the bridging struts, by contrast, one
bridging strut is offset toward the transverse axis and, as seen
from the latter, extends in front of the pair of eyelets which lie
opposite each other on the two brace axes.
[0016] The bone plate has a material thickness in the range from
0.5 mm to 1.5 mm and is preferably made of titanium of quality
grade 1 or grade 2. The bone screws inserted in the compression
holes and in the fixation holes are provided for monocortical
screwing to the bone fragments.
BRIEF DESCRIPTION OF THE ATTACHED DRAWINGS
[0017] FIG. 1A shows a plan view of a symmetrical bone plate with 4
compression holes and 4 cylindrical fixation holes;
[0018] FIG. 1B shows the view according to FIG. 1A, in a cross
section along the line A-A;
[0019] FIG. 2 shows a plan view of an asymmetrical bone plate with
4 compression holes and 4 cylindrical fixation holes;
[0020] FIG. 3 shows a plan view of a symmetrical bone plate with 4
compression holes;
[0021] FIG. 4 shows a plan view of a symmetrical bone plate
according to FIG. 1A with 2 compression holes oriented at an angle
to the longitudinal axis;
[0022] FIG. 5A shows the symmetrical bone plate according to FIG. 3
at the start of compression osteosynthesis with an open bone
fracture;
[0023] FIG. 5B shows the view according to FIG. 5A during
compression osteosynthesis with a closed bone fracture;
[0024] FIG. 6A shows the symmetrical bone plate according to FIG. 3
fitted laterally on the mandible with a jaw angle fracture;
[0025] FIG. 6B shows the symmetrical bone plate according to FIG.
1A fitted laterally on the mandible with a jaw angle fracture;
[0026] FIG. 7A shows the symmetrical bone plate according to FIG.
1A fitted frontally on the mandible with a median fracture; and
[0027] FIG. 7B shows the asymmetrical bone plate according to FIG.
2 fitted laterally on the mandible with a paramedian fracture.
ILLUSTRATIVE EMBODIMENTS
[0028] In the following detailed description of illustrative
embodiments of the osteosynthetic bone plate according to the
invention, reference is made to the attached drawings.
[0029] FIGS. 1A and 1B
[0030] The bone plate 1 constructed symmetrically in relation to
the longitudinal axis X and the transverse axis Y has two plate
braces 2 running parallel to the longitudinal axis X and spaced
apart from one another. The plate braces 2 extend along the brace
axes Z. Each plate brace 2 ends at the outside with a disk-shaped
plate member 3, at the center of which a cylindrical fixation hole
4 is provided which, on the plate upper side 5, has a countersink 7
for receiving a screw head in a partially recessed manner. The
fixation hole 4 opens out cylindrically on the plate lower side 6,
which faces toward the bone fragments that are to be joined. From
the plate members 3, an attachment strut 8 extends along each of
the brace axes Z toward the transverse axis Y.
[0031] The four attachment struts 8 each adjoin an eyelet 9 of the
compression part 10 of the bone plate 1. Provided in each eyelet 9
there is an oblong compression hole 11 of conventional contour
whose longitudinal extent lies on the brace axis Z. Toward the
transverse axis Y, the individual compression hole 11 has, on the
plate upper side 5, a countersink 12 which runs out harmonically in
the compression hole 11 increasingly away from the transverse axis
Y. Thus, a bone screw fitted as it were eccentrically in the
compression hole 11 is pressed in a known manner toward the
transverse axis Y with its head penetrating into the compression
hole 11 and in so doing entrains the screwed-on bone fragment with
it. If the bone screws are positioned symmetrically to the
transverse axis Y, the bone fragments which are to be joined
together are pressed on each other in the sense of compression
osteosynthesis.
[0032] Extending between the eyelets 9 on both sides of the
transverse axis Y on a plate brace 2 there is a connecting strut 13
which runs on the brace axis Z and connects the two eyelets 9 to
each other. Compared to the attachment struts 8, the connecting
struts 13 have a greater width and for this reason they also have a
higher degree of rigidity. The two plate braces 2 are connected to
one another by two bridging struts 14 symmetrical to the transverse
axis Y. The bridging struts 14 each extend laterally from the
junction of the attachment strut 8 with one eyelet 9 on one brace
axis Z to the junction of the attachment strut 8 with the opposite
eyelet 9 on the other brace axis Z. As the bone plate 1, with a
thickness of for example 1.0 mm, is made of titanium of quality
grade 1 or grade 2 with two plate braces 2 and the bridging struts
14, the bone plate 1 can be bent to correctly match the respective
geometry of the bone fragments and it also has sufficient rigidity
for positionally stable fixation of the bone fragments.
[0033] FIG. 2
[0034] The difference from bone plate 1 in FIG. 1 is that in the
bone plate 1 shown here the bridging struts 14 connecting the two
plate braces 2 are arranged asymmetrically with respect to the
transverse axis Y. The right bridging strut 14 again extends
laterally from the junction of the attachment strut 8 with an
eyelet 9 on one brace axis Z to the junction of the attachment
strut 8 with the opposite eyelet 9 on the other brace axis Z. By
contrast, the left bridging strut 14 is offset toward the Y axis;
this bridging strut 14 extends laterally from in front of the
junction of the connecting strut 13 with one eyelet 9 on one brace
axis Z to a position in front of the junction of the connecting
strut 13 with the opposite eyelet 9 on the other brace axis Z. A
bone plate 1 configured in this way is primarily of use for
application to a paramedian fracture of the mandible, where the
issuing nerve must not be pressed by a plate part (see description
of FIG. 7B).
[0035] FIG. 3
[0036] In this simplified bone plate 1, only the compression part
10 is provided. The outwardly directed attachment struts 8 and the
plate members 3 at the very outer ends with the fixation holes 4
are not present here. As in the embodiment according to FIG. 1, the
bridging struts 14 in principle extend from the outer flank of one
eyelet 9 on one brace axis Z to the outer flank of the opposite
eyelet 9 on the other brace axis Z. An illustrative application of
this bone plate 1 is described with reference to FIG. 6A.
[0037] FIG. 4
[0038] The particular feature of this symmetrical embodiment
compared to the basic embodiment according to FIG. 1 is that the
two oblong compression holes 11 with the eyelets 9 on the lower
plate brace 2 do not extend longitudinally on the brace axis Z or
parallel to the longitudinal axis X, but assume the angle .alpha. .
This is useful in cases where, in a special fracture pattern, a
pressure between the fragments is to be built up extending
obliquely from the lower plate brace 2 to the longitudinal axis
X.
[0039] FIGS. 5A and 5B
[0040] The two figures illustrate the principle of compression
osteosynthesis using a bone plate 1 according to FIG. 3 by way of
example.
[0041] In the starting situation (see FIG. 5A), the fracture line
22 to be closed is present between the two bone fragments 20, 21 to
be joined, and the bone plate 1 is to be placed with its
compression part 10 across this line. The bone plate 1 is of the
type referred to as mini plates. The bone screws 30 are introduced
into the oblong compression holes 11, directed away from the
countersinks 12, i.e. at the greatest possible distance from one
another as viewed on the respective plate brace 2 and the
associated brace axis Z. As can be seen, the screw heads 31 of the
bone screws 30 are screwed preferably monocortically into the bone
fragments, i.e. farther away from the fracture line 22 and the
transverse axis Y.
[0042] FIG. 5B shows that, as the bone screws 30 are screwed
farther into the bone fragments 20, 21, the screw heads 31 come to
lie in the countersinks 12--as a result of the specially contoured
countersinks 12 in the compression holes 11. The bone fragments 20,
21 hanging on the bone screws 30 are entrained in the direction of
the transverse axis Y and the fracture line 22 until finally the
fracture line 22 is closed and the bone fragments 20, 21 are joined
together with compression.
[0043] FIGS. 6A to 7B
[0044] This sequence of figures illustrates examples of some
applications of different embodiments of the bone plate 1 according
to the invention in mandibular fractures.
[0045] FIG. 6A: A jaw angle fracture is treated with a bone plate 1
in the configuration according to FIG. 3, which only has the
compression part 10. The bone plate 1 fixed with four bone screws
30 spans the fracture line 22 and connects as bone fragments 20, 21
the body of the mandible and the ramus of the mandible.
[0046] FIG. 6B: A jaw angle fracture is likewise treated with a
symmetrical bone plate 1 in the configuration according to FIG. 1
which comprises the compression part 10 and the attachment struts 8
extending beyond this and the outer plate members 3. The body of
the mandible and the ramus of the mandible are once again connected
as bone fragments 20, 21 across the fracture line 22. In addition
to the four bone screws 30 in the compression part 10, the bone
fragments 20, 21 are secured with in each case two bone screws 30
inserted in the outer plate members 3.
[0047] FIG. 7A: A median fracture of the mandible is treated
likewise with a symmetrical bone plate 1 in the configuration
according to FIG. 1, which comprises the compression part 10 and
the attachment struts 8 extending beyond this and the outer plate
members 3. Two parts of the broken body of the mandible as bone
fragments 20, 21 are connected to one another across the median
fracture line 22. Here once again, in addition to the four bone
screws 30 in the compression part 10, the bone fragments 20, 21 are
fixed in a positionally stable manner with the two bone screws 30
inserted in the outer plate members 3.
[0048] FIG. 7B: An asymmetrical bone plate 1 in the configuration
according to FIG. 2 is used for the illustrated treatment of a
paramedian fracture of the mandible. This bone plate 1 consists of
the compression part 10, the attachment struts 8 extending beyond
the latter, the outer plate members 3, and the asymmetrically
arranged bridging struts 14 between the two plate braces 2. The
bone plate 1 is used to connect, as bone fragments 20, 21, two
parts of the eccentrically broken body of the mandible across the
paramedian fracture line 22. The emergent nerve 40 (mental foramen)
lies free and is not pinched by any of the plate parts. The bone
fragments 20, 21 are secured in each case by four bone screws 30 in
total.
* * * * *