Note: Descriptions are shown in the official language in which they were submitted.
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The invention concerns a setting device for the fractures of
tubular bones, consistin~ of a longitudinally extended
f lattened setting element, with an essentially rectangular
cross-section, of tissue compatible hi~h-density material, in
particular implant steel, in each end section of which there
are at least two bores which extend throu~h the opposite wide
sides, and bone screws which are guided through these bores.
The setting device is most commonly used on fractures of the
long tubular bones of the lower extremities.
Operative stabilisation of tubular bone fractures has hitherto
been carried out by using plate osteosynthesis, marrow pinning(intramedullary
nailing) or an external setting device. me choice of the stablilsation
procedure is dependent! on the one hand. on the specific type
of fracture and, on the other, is decisively determined by the
significance that the surgeon attributes to the biomechanical
and the biological procedures durin~ the healing of the bone
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fracture.
~he healing of the bone fracture is assisted if there is no
relative movement between the two fractured pieces of bone. It
is the aim of every conservative and operative measure to
minimise these relative movements.
However, recent investigations suggest that this complete
immobilisation is not necessary to the same extent in all
phases of fracture healing for all directions of movement and,
on the contrary, micromovements in the axial direction of the
healing of the fractured bone could even be beneficial.
Stabilisin~ systems such as the marrow pin and the external
setting device do, under certain conditions, permit an axial
compression of the fractured bone ends and the forming callus
respectively, dependant on the body weight. This method of
assisting fracture healin~ can always be applied following an
initial phase if either an uncomplicated type of fracture or
the method of ~etting used means that no shearing stresses or
torsion pressures are to be expected in the fracture gap.
The biological aspects of the healing of fractured bones
predominantly concern the blood vessel supply to the newly
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forming bone. In this case, the periosteum which surrounds the
outside of all healthy bone, plays a decisive role, but so,
too, does the marrow cavity.
It is therefore possible to compi le the following requirements
for a setting system in the tubular bone area, namely an
exclusion of all transverse forces, as well as of flexural and
torsional m~nts,frcn the area of the fracture, a normal force,
which is applied as required, in the area of the fracture, and
no additional circulatory disturbances caused by the method of
setting i,n th2 area of the fracture. The initially mentioned
methods of setting only partially fulfil these requirements.
Plate osteosynthesis, whereby a dish-shaped multi-holed plate
1ies adjacent to the periosteum over a relatively great length,
but most importantly, the area of the fracture, can, because
of circulatory disturbances, lead to delays in the healing and
to bone necroses.
Marrow pinning or lock nailing, whereby a metal pin which
f i 1 Is the marrow cavity is pushed into the inside of the
tubular bone can likewise lead to considerable circulatory
disturbances though in this case they come from the inside of
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the tubular bone. A central splintage near the neutral fibre is, in
addition, not a good method of protection against alternating
flexural stresses in the area of the fracture.
The external setting device is concerned with a stabilising
system whereby screws are anchored - proximally and distally
related to the fracture area- into the bone and pass to the outside
throu~h the skin, where they are connected to a stable force
support device. A setting system of this type is not in
immediate proximity to the fracture aperture and does not.
therefore, lead to circulatory disturbances. There is,
however, an important disadvantage in that the transmission of
force to the force support device occurs via the bone screws,
which are long and therefore elastic in all directions,
thus rendering it difficult to estimate the force qradient
across the setting device and the bone respectively. A
dynamic ad~ustment according to requirements, i.e. permitting
normal forces in a later stage of the healing process of the bone fracture
is usually only possible in a limited manner, as, due to the
large distance between the bone axis and the force support
device and to flexural moments in the force support device whlch
is connected therewith, a tiltin~ or jamming of the system
usually occurs. In addition, an external stabilising system
signifies a considerable danger of infection and requires
intensive nursin~.
A known stabilisation system for fractures in the vertebral
area renders possible, by means of its compact construction,
implantation under the skin, so that the risk of infections is
reduced and patient comfort is improved. However, due to its
construction, this ri~id system is not suited to the
stabilisation of tubular bone fractures and with re~ard to the
dynamic alteration possibilities it only offers a gradual
improvement in comparison with the external setting system.
The object on which the invention is based is to form the
settin~ device initially mentioned in such a way that it can
be implanted under the skin, eliminate8 tran~ver~e forceq a~ well
as flexural and torsional moments in the area of the fraeture,
enables metering of the normal force in the area~of the fracture
and reduces circulatory disturbances in the fracture area to a
minimum.
Startin~ from the setting device of the initially mentioned
type, the o~ject is achieve~ in that the settin~ element is
equipped with a connection section, between the rigid end
sections which are provided with anchorage devices for the bone
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screws, the cros~ 3ection of which connection E~ection is smal-
ler than that of the end sections.
The setting device according to the invention has a flattened
force support device of implant steel, which is positioned in
the vicinity of the fractured tubular bone, avoiding any
surface contact with the tubular bone. Between the two
ri~id end sections of this force support carrier or setting
element there is a central connection piece, which, in
comparison with the end sections, shows a certain
elasticity~ The end sections accommodate at least two bone
screws each, which are firmly held in the stable outer layer
of the tubular bone at a sufficient distance from the fracture
zone. The entire stabilising system is built in an extremely
compact manner and makes implantation under the skin possible.
The settin~ device can be realised as a modular system.
Thereby the bone screws, as well as the fastenin~ of the bone
screws in the force support device, are standardised. The
settin~ element itself forming the force support device, is
inteqral or made of a sinale piece, and is also prcvided with standardised
end sections, while the central connectin~ section can be
manufactured in various stren~ths, so that the sur~eon can
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select the optimum force support device depending on the
wei~ht of the patient and the type of fracture.
In the case of setting devices according to the invention, the
cross-sectional area which is bordered by two narrow sides and
two wide sides of the connectin~ section of the settin~ device
is reduced by reducin~ the dimensions of the narrow sides, or
the dimensions of the wide sides, or the dimensions of the
narrow and wide sides, in relation to the end sections. In
this connection, the reduction of the dimensions of the narrow
8ide8 of' the connecting section like the reduction of ~he
dimensions of the wide sides of the connecting section is
conveniently 30 to 70%.
The reduction of the cross-section in the direction of the
narrow side of the connection section leads to normal forces
occurin~ in the fracture area, dependin~ upon the load on the
bone. The side of the bone which faces away from the settin~
element is in this connection subjected to a ~reater
compression than the side of the bone whlch faces the settLn~
element. When the load force has ceased, a tensile ~orce
acts in the opposite manner, owin~ to the elastic
- resettin~ tendency of the force support device. When there is
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an alternating normal force load, for example ~uring walking,
a tensile and thrust load occurs approximately axially in
the fracture aperture. The ri~idity of the force support
device and the short bone screws bring about a sufficient
degree of settin~ in all other directions of movement, so that
no transverse forces or flexural and torsinal moments occur
in the fracture ~ap.
The constriction o~ the connecting section in the direction of
the wide side enables the device to be mou~ted so as to protect
the tissu,es, with as little space as possible for the setting
element in the area of the fracture zone, in order not to
cause any additional circulatory disturbances.
The settin~ element may consist of two setting element parts
which lie flat on top of each other are fastened to each
other in the end sections, and of which the connection
sections can be moved away from each other by a s~reader
device. The spreader device may consist of a headless screw
screwed into a threaded ~ore in the connection section of the
one setting device part. In this arrangement the two settin~
element parts may be of differing thicknesses in the direction
of their narrow ends, at least on their connection sections.
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In this arrangement the force support device that forms the
settin~ element is divided in the direction of its narrow
side, for example into setting element parts, one thicker and
one thinner, which lie flat on top of each other and which are
rigidly connected to each other only in the area of the end
sections, for example by means of screwing. In the area of the
connection section, the two setting element parts can be
spread from each other by means of a spreader device.
If in thds case the thinner setting element part is positioned
near to the bone, compression on the fracture fissure can be
exerted by spreading in the area of the connection section.
If conversely, the th~cker setting element part is positioned
near to the bone, then the two fracture ends are moved away
from each other by spreading in the area of the connection
section, which may be necessary for maintaining distance if
the bone is fragmented. In both cases, the resilient parts of
the connection sections are retained, whereas in the case of
the force support carrier divided into two only the flexion
characteristics have altered.
If the bone screws are seated in the end sections of the
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setting device in such a way that they can rotate, this will
ma~e a better adaptation to the individual fracture situation
and correction of erroneous borings possible. Further, the
bone screws can be mounted under pretension, which can, under
certain circumstances, prevent a loosening tendency.
On the end sections of the setting element, guide sections for
the shafts of the bone screws may be provided. The bone screws
are secured against axial displacement in the setting elements
by a tension device and are stabilised by a guide section,
formed as~ a tapered segment, until immediately before they
enter the bone.
The setting device according to the invention is used as
follows:
Following the repositioning of the fracture, the force support
device, formed by the set-tin~ element, is connected to the two
bone ends in that firstly, the anchoring holes are drilled
in the bone corticalis with the aid of a boring stencil which
has been screwed onto the force support device and, if
necessary, an appropriate thread is subsequently cut. The bone
s ~ew s then gras ed r~ its r r end with ~ ~ensio~ tongue
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and rotated by the force support device into the bone until it
finds a firm hold in the two opposite corticalis layers. This
procedure is repeated for all the remaining fastening points
of the force support device. The bone screws are now shortened
at the hei~ht of the external surface of the force support
device with a bolt clipper. The screws are axially fastened by
~eans of a lon~itudinally slit cone which is pushed over the
bone screw and pressed by a screw which is provided with a
flat head and holds the cut-off end of the bone screw in the
centre, finds a secure hold in a counter support, which is
also coni~al, in the area of the taper seyment shaped ~uide.
If the force support device is in a divided form, then, when
the setting device has been mounted, with the aid of the
spreader device which is formed b~ the Imbus headless ssrew,
the stress on the fracture zone can be applied or released.
By means of a small incision in the skin, the headless screw
can also be reached in the later sta~es of the fracture
healin~ process. in order to adapt the elasticity of the force
support device to the requirements of the particular staaes in
the healin~ of the fracture.
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With reference to the drawings embodiments of the invention
will be explained in more detail. In the drawings:
ig. 1 shows in perspective, a setting device, mounted over
the fracture in a tubular bone;
ig. 2 shows the setting device of Figure 1, rotated
through approxiamately 90~;
Fig. 3 shows in cross-section, the positive-locking
~securing of the bone screw in the settin~ element;
ig. 4 shows in cross-section, the rotatable securing of
the bone screw in the setting element rotated
through approx. 20;
ig. 5 shows in perspective, an end section of a setting
device with a tubular bone to clarify the
possibilities of rotation;
ig. 6 shows in a view as for Figure 1, a modification of
the setting device;
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ig. 7 shows in cross section, the connection section shown
as a detail A of Figure 6 in the state where it has
not been spread, and
ig. 8 shows in a view as for Figure 7, the connection
section in the spread state.
The tubular bone section 1 shown in Figs. 1 and 2 is fractured
along a first fracture line 4, which branches into two
fracture lines 3, thereby forming a broken out segment 2,
which is inserted again into the tubular bone section 1, the
entire fracture being set with the aid of a settin~ element
20.
The setting element 20 has two end sections 21, which are
connected to each other by a connection section 31. In each
end section 21 two borings are provided, at a distance from
each other through which bone screws 10 are guided. Each
bone screw 10 has a shaft 13 and a thread 14. The shaft 13 of
each bone screw is guided in a taper segment ~haped guide
section 15, which is mounted on the setting element 20 on the
side opposite the tubular bone section 1. The proximal end of
the bone screw is surrounded by a screw 11 ~hich is prov1ded
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with a flat head and a central boring and comprises two
diametrically positioned borings 12 for the engagement of the
ends of a screwdriver of appropriate form.
The settin~ element 20 has a longitudinally extended flattened
form with an essentially rectangular cross-section. The end
sections 21 are relatively rigid. The cross-section thereof
has two opposite wide sides 22 and two opposite narrow sides
23. The connection section 31 is resilient in comparison with
the rigidity of the end sections 21, this being achieved in
that the ;wide side 32 thereof is smaller than the wide side 22
of the end section 21 and in that the narrow side 33 thereof
has a shorter extension than the arrow side 23 of the end
section 21. In the embodiment shown in figures 1 and 2 both
the wide side 3? and the narrow side 33 of the connection
section 31 are reduced in their extension with respect to the
wide side 22 and the narrow side 23 of each end section 21,
namely by approx. 40~.
As shown in Fig. 3, the bone screws 10 sit in the end section
21 in such a way that the shaft 13 thereof extends through a
taper seqment shaped quide section 15, the axial setting beinq achieved
with the aid of a lon~itudinally slit cone 16 which is pressed
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into a counter-bearing in the taper segment shaped guide
section 15 by the screw 11. The guide section 15 lies with its
base over a large area on the end section 21 and is connected
thereto in a force-locking manner.
In the case of the modification shown in Fig. 4, the bone
screw 11 is held by its shaft 13, to~ether with the ~uide
section 15 with the cone 16, in a spherical section 17 which
is positioned in a rotatable manner in the setting element 20,
whichr in this embodiment, is formed by two setting element
parts 25 and 26. By means of the force-locking setting of the
spherical section 17 between the setting element parts 25 and
26, which are attached to each other by screws 24, as is shown
in fiqure 5, the bone screw 10 can be rotated by a given t
amount and thus be screwed into a preliminary bore in the
tubular bone section even if this prellminary bore is not exactly
parallel to the preliminary bore for the other bone screw in
the same end section.
In the case of the modification shown in Figs. 6 to 8 the
tubular bone section 1 has a continuous fracture aperture 4.
The setting element 20 forming the force support carrier is
divided, in the e~tension of its narrow side into two setting
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element parts 25 and 26 which lie flat one on top of the other so
that the seperatin~ seam also extends through the connection
section 31, which is thus separated into a connection section
35, which is shown as being thick in Figs. 6 to 8, and a
connection section 36, which is shown as bein~ thinner. The
two setting element parts 25 and 26 are, in the area of their
end sections 21, each fastened onto each other by four screws
24. In the thicker connection section 35, which faces away
from the tubular bone section 1, an Imbus headless screw 34 is
screwed into a threaded bore. With the aid of this Imbus
headless .screw 34, the connection section 36 facing the
tubular bone section 1 can be moved from the position abutting
in a flat manner shown in Fig. 7 to the outwardly curved
position, shown in Fig. 8, whereby the forces exerted on the
tubular bone section 1 on both sides of the fracture aperture
4 can be altered.
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