U.S. patent application number 12/727722 was filed with the patent office on 2010-07-08 for self-boring and self-tapping screw for osteosynthesis and compression.
This patent application is currently assigned to Newdeal S.A.. Invention is credited to Eric Stephane Fourcault, Bertrand Xavier Francois Gauneau, Jean-Christophe Alain Giet, Theo Jan Maria Knevels.
Application Number | 20100174323 12/727722 |
Document ID | / |
Family ID | 29720102 |
Filed Date | 2010-07-08 |
United States Patent
Application |
20100174323 |
Kind Code |
A1 |
Fourcault; Eric Stephane ;
et al. |
July 8, 2010 |
SELF-BORING AND SELF-TAPPING SCREW FOR OSTEOSYNTHESIS AND
COMPRESSION
Abstract
The invention provides an osteosynthesis and compression screw
that is self-boring and self-tapping for the purpose of coaptation
of small bone fragments. The screw comprises: a proximal portion
formed by a screw head provided with an outside thread; an
intermediate portion having no thread; and a distal portion
provided with an outside thread. Wherein: each of the screw head
and the distal portion includes at least one groove, firstly
extending over the entire axial length of its thread, and secondly
being formed through each thread in such a manner to form tapping
means; and the terminal zone of the distal portion is provided with
preparation means for preparing a housing in the bone fragments for
receiving the intermediate and distal portions of the screw.
Inventors: |
Fourcault; Eric Stephane;
(Lyon, FR) ; Knevels; Theo Jan Maria; (Grimbergen,
BE) ; Giet; Jean-Christophe Alain; (Lyon, FR)
; Gauneau; Bertrand Xavier Francois; (Lyon, FR) |
Correspondence
Address: |
THOMAS, KAYDEN, HORSTEMEYER & RISLEY, LLP
600 GALLERIA PARKWAY, S.E., STE 1500
ATLANTA
GA
30339-5994
US
|
Assignee: |
Newdeal S.A.
Vienne
FR
|
Family ID: |
29720102 |
Appl. No.: |
12/727722 |
Filed: |
March 19, 2010 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10614496 |
Jul 7, 2003 |
7708738 |
|
|
12727722 |
|
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|
|
Current U.S.
Class: |
606/304 ;
606/308 |
Current CPC
Class: |
A61B 17/863 20130101;
A61B 17/864 20130101; Y10S 606/916 20130101; A61B 17/8635
20130101 |
Class at
Publication: |
606/304 ;
606/308 |
International
Class: |
A61B 17/86 20060101
A61B017/86 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 5, 2002 |
FR |
02 08589 |
Claims
1. An osteosynthesis and compression screw for coaptation of small
bone fragments, the screw being formed by a single longitudinal
body having a longitudinal axis, and comprising: a proximal portion
formed by a screw head provided with an outside thread, said
proximal portion being of diameter greater than the diameter of the
remainder of the screw; an intermediate portion having no thread; a
distal portion provided with an outside thread; at least one groove
present in the distal portion, for performing tapping; wherein: the
groove present in the distal portion is of helical shape and
extends over substantially the entire axial length of the thread
that the distal portion is provided with, the terminal zone of the
distal portion is provided with preparation means for preparing a
housing in the bone fragments for receiving the intermediate and
distal portions of the screw, said preparation means comprising at
least one tooth.
2. A screw according to claim 1, wherein the longitudinal body
comprises a groove present in the proximal portion.
3. A screw according to claim 2, wherein the groove present in the
proximal portion is of helical shape.
4. A screw according to claim 1 wherein the obliqueness of the
helical groove present in the distal portion lies in the range
20.degree. to 40.degree., and is preferably about 25.degree..
5. A screw according to claim 3 wherein the obliqueness of the
helical groove present in the proximal portion lies in the range
20.degree. to 40.degree., and is preferably about 25.degree..
6. A screw according to claim 2, wherein the depth of each groove
is constant.
7. A screw according to claim 2, wherein the depth of each groove
varies regularly from the start towards the finish of each
groove.
8. A screw according to claim 7, wherein the depth of each groove
increases going towards the terminal zone of the screw.
9. A screw according to claim 8, wherein the final portion of each
groove penetrates into the thickness of the body of the screw.
10. A screw according to claim 1, the screw being provided with a
central longitudinal bore to form a hollow screw.
11. A screw according to claim 10, wherein each junction between
the groove present in the distal portion and the central bore
includes a tooth forming the preparation means.
12. A screw according to claim 1 wherein the diameter of the
proximal portion increases going towards the proximal extremity of
the screw.
13. A screw according to claim 1 wherein the proximal portion
extends axially over a length that is less than the length over
which the distal portion extends axially.
14. A screw according to claim 1 wherein the groove present in the
proximal portion is a longitudinal groove.
15. A screw according to claim 1 wherein the intermediate portion
is in the form of a substantially cylindrical portion that is
smooth and of constant diameter.
16. A screw according to claim 1 wherein the pitch of the thread of
the proximal portion is shorter than the pitch of the thread of the
distal portion.
17. A screw according to claim 1 wherein said tooth extends
substantially axially.
18. A screw according to claim 1 for joining together small bone
fragments of the phalanges of the toes or the fingers.
Description
CROSS REFERENCE RELATED APPLICATION
[0001] This application is a continuation application, which is
based on and claims priority to co-pending U.S. Utility patent
application Ser. No. 10/614,496, filed on Jul. 7, 2003, which
claims priority to French Application No. 02 08589, filed Jul. 5,
2002, which is entirely incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to the technical field of
surgical screws, and in particular to osteosynthesis screws for
joining together and compressing two bone fragments in order to
achieve rapid osteosynthesis with the formation of bone callus, the
present invention applying more particularly to joining together
small bone fragments such as those of the phalanges of the toes or
the fingers.
[0003] The present invention relates to an osteosynthesis and
compression screw for coaptation of small bone fragments, the screw
being formed by a single longitudinal body, and comprising:
[0004] a proximal portion formed by a screw head provided with an
outside thread, said proximal portion being of diameter greater
than the diameter of the remainder of the screw;
[0005] an intermediate portion having no thread; and
[0006] a distal portion provided with an outside thread.
BACKGROUND OF THE INVENTION
[0007] When dealing with broken bone fragments of small size, such
as those of the phalanges or the toes, the small size of the bones
or bone fragments concerned poses difficult problems to be solved
by the practitioner in charge of reducing the fracture and then
putting the bones into place with sufficient compression to ensure
that the fracture is properly resorbed.
[0008] In order to ensure rapid osteosynthesis between two bone
fragments, leading specifically to the rapid formation of a high
quality bone callus enabling a rapid return to normal function, it
is necessary for two small bone fragments to be positioned and
fixed relative to each other with relative longitudinal compression
being established between the two bone fragments.
[0009] Clearly, given the very small size of the bone fragments
concerned, and the correspondingly small size of the osteosynthesis
screws used, it is difficult to establish longitudinal compression
between the two bone fragments concerned.
[0010] It is particularly important and difficult to master this
type of surgical act, given that the manipulations imposed by the
small size of the bones and the screws are fiddly, and given that
the small bone fragments need to be positioned relative to one
another and compressed and put into final position with very great
precision since the purpose is to restore total mobility functions,
such as handling functions or walking, in particular when dealing
with bones of the hand or of the foot.
[0011] It is thus already known to use staples that are put into
place directly on the two bone fragments to be joined together.
Such a technique is poorly adapted to the type of surgery under
consideration insofar as putting staples into place relative to the
pieces of bone does not make it certain that the bone fragments to
be joined together are properly positioned. In practice, it is not
possible with staples to obtain fixing and compression.
[0012] Proposals have already been made to use osteosynthesis
screws of the kind used for coaptation of bones of large size and
suitable not only for joining bones together, but also for
performing the additional function of applying longitudinal
compression.
[0013] Thus, proposals have already been made to use an
osteosynthesis and compression screw comprising a proximal portion
formed by a screw head provided with an outside thread and
presenting a diameter greater than that of the remainder of the
screw. The screw presents an intermediate portion without any
thread in order to improve relative sliding between the bone
fragments for joining together while the screw is being screwed in,
and said intermediate portion is followed by a distal portion which
is also provided with an outside thread.
[0014] Such screws improve surgical operating conditions greatly
because of the improve ease with which they can be put into
place.
[0015] Nevertheless, such screws still suffer from drawbacks
associated in particular with a certain number of additional
actions that the surgeon needs to perform such as prior drilling of
a hole in order to ensure that the threads of the screw hold
strongly both in the distal portion and in the proximal portion
having the head of larger diameter. This increases the number of
actions the surgeon needs to perform and therefore increases the
duration of the operation.
[0016] Considerable improvements have been provided to screws of
this type but they relate essentially to increasing the compression
ability of such screws, for example by incorporating a two-start
distal thread, without taking account of total time required for
surgery but while maintaining excellent holding strength and
compression properties.
[0017] Conventional self-boring and self-tapping surgical screws
are also known, with the tapping portion of such a prior screw
nevertheless being restricted to the distal portion thereof. Screws
known in the prior art possess a screw head that is not threaded
and that must specifically be embedded in the bone by previously
making a suitable recess using a special tool. Such screws thus
require an additional tool to be used which implies an 30
additional act leading to increased manipulation, to additional
risk of accidents or faulty installation, and, in all, lengthening
the time required for surgery.
OBJECTS AND SUMMARY OF THE INVENTION
[0018] The present invention consequently seeks to remedy the
various drawbacks outlined above and to propose a novel
osteosynthesis and compression screw for coaptation of small bone
fragments, which screw is self-boring and self-tapping so as to
simplify installation thereof and so as to enable installation to
be controlled as well as possible.
[0019] Another object of the invention is to propose a novel
osteosynthesis screw which is not only self-boring and
self-tapping, but which also presents excellent strength
properties.
[0020] Another object of the invention is to propose a novel
osteosynthesis screw presenting excellent tapping properties while
also being particularly well balanced geometrically.
[0021] Another object of the invention is to propose a novel
osteosynthesis screw presenting excellent compression properties
while being particularly well balanced mechanically.
[0022] The objects given to the invention are achieved by means of
an osteosynthesis and compression screw for coaptation of small
bone fragments, the screw being formed by a single longitudinal
body having a longitudinal axis, and comprising:
[0023] a proximal portion formed by a screw head provided with an
outside thread, said proximal portion being of diameter greater
than the diameter of the remainder of the screw;
[0024] an intermediate portion having no thread; and
[0025] a distal portion provided with an outside thread;
wherein:
[0026] each of the screw head and the distal portion includes at
least one groove, firstly extending over the entire axial length of
its thread, and secondly being formed through each thread in such a
manner to form tapping means; and
[0027] the terminal zone of the distal portion is provided with
preparation means for preparing a housing in the bone fragments for
receiving the intermediate and distal portions of the screw.
BRIEF DESCRIPTION OF THE FIGURES
[0028] Other advantages of the invention are explained in greater
detail in the description below, to be read with the help of the
accompanying drawing provided purely for non-limiting explanatory
purposes, and in which:
[0029] FIGS. 1 and 2 are general perspective views showing an
embodiment of an osteosynthesis and compression screw in accordance
with the invention; and
[0030] FIG. 3 is a fragmentary perspective view showing the shape
of the distal portion of the screw in accordance with the
invention.
DETAILED DESCRIPTION
[0031] The osteosynthesis and compression screw shown in the
figures is for joining together or "coaptation" of two small bone
fragments, and in particular in its preferred application, two
phalanges of the foot or the hand that have been fractured.
[0032] The osteosynthesis and compression screw of the invention is
made from a biocompatible metal material and is formed by a single
elongate body presenting a longitudinal axis A defining an axis of
revolution.
[0033] As shown in the figures, the osteosynthesis screw comprises
a proximal portion 2 formed by a screw head 3 provided with an
outside thread 4 comprising a series of helical threads 4A, said
proximal portion 2 being of diameter D greater than the diameter of
the remainder of the screw.
[0034] Thereafter, the osteosynthesis screw of the invention has an
intermediate portion 5 that is not threaded, advantageously being
in the form of a substantially cylindrical portion 5A that is
smooth and of constant diameter.
[0035] The end of the intermediate portion 5 is extended by the
distal portion 6 of the osteosynthesis screw, said distal portion
being provided with an outside thread 7 extending helically, having
individual threads 7A all the way to the terminal zone 8 of said
distal portion 6.
[0036] In the invention, each of the screw head 3 and the distal
portion 6 comprises at least one groove 10 extending substantially
longitudinally relative to the general direction given by the
longitudinal axis A over the full axial length of each thread 4, 7
and regardless of the shape of the groove 10, for example
regardless of whether it is longitudinal or advantageously helical,
said groove extending across each thread 4, 7, i.e. occupying the
full height of each thread 4A, 7A so as to form tapping means of
the screw. The screw of the invention thus comprises at least one
pair of grooves 10 for performing tapping, both in the distal
portion and in the proximal portion.
[0037] In the invention, the osteosynthesis screw of the invention
also comprises, at the terminal zone 8 of the distal portion 6,
means 11 for preparing a housing in the bone fragments for
subsequently receiving the distal portion 6 and the intermediate
portion 5 of said screw.
[0038] Advantageously, the compression effect is obtained by making
the screw so that its proximal portion 2 has a thread at a pitch
that is smaller than that of the thread of the distal portion
6.
[0039] Because of the technical means implemented in this way, the
osteosynthesis screw of the invention serves not only to compress
axially two bone fragments that are to be joined together by means
of its two outside threads 4 and 7 in combination with the
intermediate portion 5 whose smooth appearance allows the two bone
fragments to slide towards each other, but also performs a
self-boring action due to the preparation means, and above all it
provides simultaneous self-tapping actions both at the head end of
the screw and at its distal end. This design feature makes it
possible to avoid prior drilling or recess forming using a special
instrument, thereby reducing the total time required for surgery
while also reducing the risk of faulty positioning since installing
the screw and establishing compression is performed as a single
action.
[0040] As shown in the figures, said at least one groove 10 present
both in the head of the screw 3 and in its distal portion 6 is
advantageously of helical shape and has the same geometrical
orientation relative to the longitudinal axis A both in the
vicinity of the head 3 and in the distal portion 6. The helical
aspect of the grooves 10 may be more or less marked depending on
the size and the shape of the screw, without that going beyond the
ambit of the invention. The geometrical orientation of the screw
may be specified by defining its obliqueness or angular orientation
relative to the longitudinal axis A of the screw. The obliqueness
of each groove 10 preferably lies in the range 20.degree. to
40.degree., and more preferably is about 25.degree..
Advantageously, the grooves 10 in the screw head 3 and in the
distal portion 6 have the same obliqueness.
[0041] Naturally, in a variant, the pair or pairs of grooves 10 may
be substantially longitudinal, i.e. they may extend substantially
parallel to the longitudinal axis A, without thereby going beyond
the ambit of the invention.
[0042] The depth of each groove 10 may be constant and equal
between the grooves in the screw head 3 and in the distal portion
6.
[0043] Nevertheless, and advantageously, the depth of the grooves
10 varies regularly going from the start towards the finish of each
groove, the "beginning" of each groove 10 in the meaning of the
invention being, by definition, the end beginning in the most
proximal portion of the screw head 3 or the distal portion 6. Thus,
in the invention, the depth of each groove 10 increases going
towards the more distal portion of the screw head 3 or of the
distal portion 6. Thus, each groove 10 extends more and more deeply
into each thread starting from the screw head 3 and gong towards
the distal portion 6, i.e. towards the terminal zone 8.
[0044] This feature which means that the depth of the groove 10 is
not constant relative to the longitudinal axis A of the screw,
serves to increase the general strength of the screw, in particular
in twisting, by significantly reducing the loss of material
relative to said longitudinal axis A.
[0045] Minimizing the relative weakness of the screw of the
invention is also made possible by using grooves 10 that are
helical since that enables the zones of weakness resulting from the
removal of material to provide a groove 10, themselves to be
distributed around the longitudinal axis A.
[0046] In particularly advantageous manner, the cross section of
the grooves 10 forms an angle that is acute, in any event less than
90.degree., so as to reduce the amount of material that is removed
from the screw, thereby minimizing the extent to which the screw is
weakened, but without spoiling its self-tapping properties.
[0047] In a preferred variant in the meaning of the invention, in
which each groove 10 grows regularly in depth going towards the tip
of the screw, the terminal fraction of the groove, i.e. its deepest
fraction, is advantageously made through the thickness of the screw
body, whereas the beginning portion of each groove 10 is made
solely through the thickness of the threads 4A or 7A. This reduces
the risk of weakening the screw as a whole.
[0048] In a preferred variant, the preparation means 11 are formed
by a tooth 11A extending substantially axially. Although the
simplest form of the osteosynthesis screw of the invention may have
a single pair only of grooves 10 in the screw head 3 and the distal
portion 6, it will be understood that the self-boring and
self-tapping properties of the screw can be improved by providing
two pairs of grooves 10, or in more preferred manner, three pairs
of grooves 10 regularly distributed angularly around the
longitudinal axis A and occupying both the proximal and the distal
portions of the screw.
[0049] In particularly advantageous manner, the two grooves 10 in a
given pair, regardless of whether they are longitudinal or helical,
can be provided in the proximal and distal portions 2 and 6 of the
screw in such a manner as to extend each other.
[0050] Naturally, in a variant, the two grooves 10 in a given pair
may also be arranged in the proximal and distal portions 2 and 6 of
the screw in such a manner as to be offset relative to each other,
so that the groove 10 formed in the distal portion 6 of the screw
does not extend the groove 10 formed in the proximal portion 2.
[0051] Such an offset can be provided with grooves 10 that are
longitudinal or helical.
[0052] When there are two grooves 10, they are advantageously
diametrically opposite, whereas in the preferred case of three
grooves 10, they are disposed at 120.degree. intervals about the
main axis A of the screw.
[0053] Naturally, depending on the size of the screws concerned, it
is possible to envisage making four or even more pairs of grooves
10.
[0054] The osteosynthesis screw of the invention could also, but
not exclusively, be provided with a central bore 12 extending
longitudinally so as to form a hollow screw as is well known to the
person skilled in the art.
[0055] Naturally, when the osteosynthesis screw of the invention is
provided with three pairs of grooves 10, the preparation means 11
are constituted simultaneously by a matching number of three teeth
11A disposed that the junctions between the three grooves 10 in the
distal portion 6 and the central bore 12.
[0056] The technical means implemented in the osteosynthesis and
compression screw of the invention first enable the surgeon to use
a self-boring and self-tapping osteosynthesis screw which can be
put into place in simplified manner, using a small number of tools
but without spoiling its strength and compression properties.
[0057] After positioning the two bone fragments for joining
together relative to each other, the surgeon can merely put the
osteosynthesis screw of the invention into position and then begin
directly turning that screw since it is simultaneously self-boring
and above all self-tapping along its entire length.
[0058] There is thus no need to use an auxiliary tool prior to
putting the screw into place for the purpose of preparing and
tapping not only the distal and intermediate portions of the screw
but also the screw head 3.
[0059] The present invention thus also provides a novel method of
surgery in which the osteosynthesis screw, by virtue of its shape,
itself serves, merely on being turned by a screwdriver, to prepare
its own housing and its own tapping without it being necessary to
perform any prior drilling.
* * * * *