U.S. patent application number 09/560716 was filed with the patent office on 2002-07-25 for locking nail for the repair of femur shaft fractures.
Invention is credited to Adam, Michael.
Application Number | 20020099379 09/560716 |
Document ID | / |
Family ID | 8242827 |
Filed Date | 2002-07-25 |
United States Patent
Application |
20020099379 |
Kind Code |
A1 |
Adam, Michael |
July 25, 2002 |
LOCKING NAIL FOR THE REPAIR OF FEMUR SHAFT FRACTURES
Abstract
The locking nail for the repair of femur shaft fractures, also
in connection with trochanteric femur fractures, comprises a
proximal nail section (2) and a distal nail section (3) adjoining
the latter, with the nail sections (2, 3) having bores (2e, 2f, 2h,
2i, 3a, 3b, 3c) for the reception of bone screws, and with the
distal nail section (3) having a curvature extending in an
anterior-posterior plane (apE) and corresponding substantially to
the antecurvature of the femur, with the proximal nail section (2)
having at least over a partial section (2a, 2b) a continuous
curvature, in particular with constant radius of curvature (R2),
extending in a lateral-medial plane (lmE).
Inventors: |
Adam, Michael; (Heimberg,
CH) |
Correspondence
Address: |
TOWNSEND AND TOWNSEND AND CREW, LLP
TWO EMBARCADERO CENTER
EIGHTH FLOOR
SAN FRANCISCO
CA
94111-3834
US
|
Family ID: |
8242827 |
Appl. No.: |
09/560716 |
Filed: |
April 27, 2000 |
Current U.S.
Class: |
606/67 |
Current CPC
Class: |
A61B 17/7233 20130101;
A61B 17/744 20130101; A61B 17/72 20130101 |
Class at
Publication: |
606/67 |
International
Class: |
A61B 017/56 |
Foreign Application Data
Date |
Code |
Application Number |
May 12, 1999 |
EP |
99 810 422.8 |
Claims
1. Locking nail for the repair of femur shaft fractures, also in
connection with trochanteric femur fractures, comprising a proximal
nail section (2) and a distal nail section (3) adjoining the
latter, with the nail sections (2, 3) having bores (2e, 2f, 2h, 2i,
3a, 3b, 3c) for the reception of bone screws, and with the distal
nail section (3) having a curvature extending in an
anterior-posterior plane (apE) and corresponding substantially to
the antecurvature of the femur, characterised in that the proximal
nail section (2) has at least over a partial section (2a, 2b) a
continuous curvature with constant radius of curvature (R2),
extending in a lateral-medial plane (lmE).
2. Locking nail (1) in accordance with claim 1, characterised in
that the partial section (2a, 2b) having a continuous curvature in
the axial direction extends at least over about one fourth of the
total length of the locking nail (1), preferably over about one
third of the total length.
3. Locking nail (1) in accordance with any one of the preceding
claims, characterised in that the proximal nail section (2),
starting from the distal nail section (3), consists of a transition
section (2a), a securing section (2b) adjoining the latter and a
thread section (2c) adjoining the latter; in that the securing
section (2b) contains bores (2e, 2f, 2h, 2i); and in that at least
the transition section (2a) and the securing section (2b) have a
common curvature with a constant radius of curvature (R2).
4. Locking nail (1) in accordance with any one of the preceding
claims, characterised in that the proximal nail section (2) has at
least one inclined bore (2e, 2f).
5. Locking nail (1) in accordance with claim 4, characterised in
that the proximal nail section (2) has at its surface at least one
notch (2g) which extends substantially parallel to the at least one
inclined bore (2e, 2f).
6. Locking nail (1) in accordance with claim 5, characterised in
that the notch (2g) is arranged to extend ventrally.
7. Locking nail (1) in accordance with any one of the claims 4 to
6, characterised in that the inclined bores (2e, 2f) extend
parallel to one another.
8. Locking nail (1) in accordance with any one of the claims 4 to
7, characterised in that two inclined bores (2e, 2f) and a notch
(2g) are arranged to extend parallel to one another and in
particular to form an isosceles or equilateral triangle.
9. Locking nail (1) in accordance with any one of the claims 3 to
8, characterised in that the thread section (2c) is designed to
extend in a straight line and runs out to the proximal nail end
(1a), with the thread section (2c) having an inner thread (2d) for
the reception of an aiming device or a tool for hammering in or
out.
10. Locking nail (1) in accordance with any one of the preceding
claims, characterised in that the bores (2e, 2f, 2h, 2i) are
arranged to extend in the proximal nail section (2) in such a
manner that their axes have an anteversion (a) of 75 degrees to 80
degrees, and in particular an anteversion (.alpha.) of 78 degrees,
relative to the distal nail section (3).
11. Locking nail (1) in accordance with any one of the claims 3 to
10, characterised in that the transition section (2a) conically
contractingly merges from the securing section (2b) to the distal
nail section (3).
12. Locking nail (1) in accordance with any one of the preceding
claims, characterised in that the latter is designed as a hollow
tube.
13. Locking nail (1) in accordance with any one of the preceding
claims, characterised in that the hollow tube has a slit (5)
extending in the axial direction in the distal nail section (3).
Description
[0001] The invention relates to a locking nail for the repair of
femur shaft fractures, also in connection with trochanteric femur
fractures, in accordance with the preamble of claim 1.
[0002] An osteosynthetic aid for the repair of intertrochanteric or
subtrochanteric femur fractures which is designed as a locking nail
with an open cloverleaf profile is known from the reference EP 0
528 128. The locking nail has inclined bores in its proximal
section for guiding and holding a femoral neck screw. The locking
nail has an axial longitudinal slit at its distal section. The
locking nail also has a bend at the transition between a proximal
partial section and a distal partial section. Disadvantageous in
this known locking nail is the fact that it is difficult to
introduce into the medullary space.
[0003] The object of the present invention is to create a more
advantageous locking nail for the repair of femur shaft
fractures.
[0004] This object is satisfied by a locking nail having the
features of claim 1. Subordinate claims 2 to 13 relate to further,
advantageous embodiments of the locking nail in accordance with the
invention.
[0005] This object is satisfied in particular by a locking nail
comprising a proximal nail section and a distal nail section
adjoining the latter, with these nail sections having bores for the
reception of bone screws, and with the distal nail section having a
curvature extending in an anterior-posterior plane and
corresponding substantially to the antecurvature of the femur; and
with the proximal nail section having at least over a partial
section a continuous curvature, in particular with constant radius
of curvature, extending in a lateral-medial plane.
[0006] The term "continuous curvature" will be understood in the
following to mean that the curvature has no point with a
discontinuity or a bend respectively, which can be mathematically
described in such a manner that the first derivative of the
curvature plot has no discontinuity or no jump-like change.
[0007] In an advantageous embodiment the proximal nail section,
starting from the distal nail section, has a transition section and
a securing section adjoining the latter with bores for the
reception of the bone screws, with the transition section and the
securing section having a continuous curvature with a constant
radius of curvature.
[0008] The locking nail in accordance with the invention is
suitable in particular for the repair of femur shaft fractures,
also in connection with trochanteric femur fractures, with the
locking nail being manufactured with lengths of about 300 mm to 500
mm due to the inter-individually differing shaping of the femur.
The locking nail is distinguished by a good mechanical hold in the
medullary cavity and has a good rotational security. A transverse
bore through which a bone screw is introduced in order to firmly
hold the locking nail axially and in the direction of rotation is
arranged in the lower distal nail section. The proximal nail
section preferably has an inclined through-bore through which a
femoral neck screw can be introduced.
[0009] The locking nail in accordance with the invention is
preferably designed as a continuous hollow tube, in particular as a
cylindrical hollow tube and consists of a body-compatible, non
corroding material such as titanium or a titanium alloy. A guide
wire is preferably introduced into the continuous hollow tube. The
locking nail could however also be designed in the shape of a bar
and have no hollow inner space extending in the axial
direction.
[0010] An advantage of the locking nail in accordance with the
invention is the fact that the latter can be introduced into the
medullary space of the femur without a greater exertion of force
even in an embodiment with low elasticity. The embodiment with low
elasticity ensures a very good mechanical hold and a good support
function in the medullary cavity.
[0011] The locking nail in accordance with the invention is
designed in such a manner that the latter is preferably introduced
into the femur or into its medullary space respectively starting
from the trochanter major, with the introduction point being
located slightly laterally with respect to the tip of the
trochanter major. Since the trochanter major is arranged closer to
the surface of the skin in comparison with the previously usual
introduction location at the femur, the introduction via the
trochanter major has the advantage that a smaller opening of the
operation field is required, which in particular reduces the danger
of infections. In addition the trochanter major is more easily
accessible in the activities required during the operation. A
locking nail was usually introduced into the medullary space in the
region of the fossa piriformis. Blood vessels etc. are also present
at this location, however, so that the introduction via the
trochanter major is more sure to avoid damage to these blood
vessels. In an advantageous embodiment the locking nail has a
securing section with a relatively small cross-section. This
enables a locking nail to be formed with a smaller total
cross-section, which has an advantageous effect on the introduction
into the medullary space and in addition requires only a small
opening of the operation field.
[0012] The locking nail which is known from the cited reference has
at the transition location between the distal and the proximal nail
section a bend location and is therefore difficult to introduce
into the medullary space in spite of the elasticity produced by the
longitudinal slit in the distal nail section since the medullary
space has a curved extent and this nail lies in contact at certain
locations at the medullary space wall or at the spongiosa and can
be introduced into the medullary space only with a greater exertion
of force. The locking nail in accordance with the invention with
the curved proximal nail section has the advantage that the latter
takes into account the anatomical shape of the medullary space in
such an advantageous manner that it can be introduced without a
greater exertion of force. In contrast to short locking nails, the
locking nail in accordance with the invention, which is designed to
be very long, must be rotated during the introduction into the
medullary space by a partial rotation about its longitudinal axis.
The locking nail in accordance with the invention has the property
that the latter rotates into the correct final position by itself
during the introduction into the medullary space since the outer
shape of the locking nail is formed in imitation of the shape of
the medullary space with respect to essential aspects. The locking
nail which is known from the cited reference has a bend at the
transition location between the proximal and distal nail section,
which prevents a rotation of its own accord during the introduction
into the medullary space. The locking nail which is known from the
cited reference has the further disadvantage that the nail which is
introduced into the medullary space is only rotatable to a limited
extent since material protrudes into the longitudinal slit and
forms an obstacle during the rotation. Since the locking nail in
accordance with the invention does not necessarily require a
longitudinal slit, it can also be manufactured more
economically.
[0013] The locking nail in accordance with the invention can have a
low elasticity and nevertheless be surely introduced without a
greater exertion of force into the medullary space. Through the
design of the locking nail in accordance with the invention a
greater force, which is directed approximately radially outwardly
and in particular weakens or destroys the femur corticalis, is
avoided during its introduction into the medullary space. Through
this it is also enabled that the femur is held together in its
anatomically correct position. It is known that an unfavourably
designed locking nail can cause the femur having the fracture to
adapt to the shape of the locking nail, which has the result that
the fixed femur has a faulty position or a deviation from the
normal position respectively.
[0014] Exemplary embodiments of the locking nail in accordance with
the invention will be explained in the following in more detail
with the help of the drawings. Shown are:
[0015] FIG. 1 a side view of the locking nail from the direction
B;
[0016] FIG. 2 a front view of the locking nail from the direction
A;
[0017] FIG. 3 a front view of the locking nail, which is rotated
slightly about its axis, from the direction C, partly in
section;
[0018] FIG. 4 a detail view of the proximal nail section from the
direction D;
[0019] FIG. 5 a detail view of the locking nail from the direction
E;
[0020] FIG. 6 a cross-section through a slit locking nail;
[0021] FIG. 7 a detail view of the securing section from the
direction F.
[0022] The locking nail 1 in accordance with FIG. 1 is formed in a
single piece and consists of a proximal nail section 2 and a distal
nail section 3 adjoining at the latter. Starting from the proximal
end 1a of the locking nail 1 the proximal nail section 2 comprises
a thread section 2c extending in a straight line and having an
inner thread 2d, adjoining thereat a securing section 2b which has
a transverse bore 2i, an oval transverse bore 2h and two inclined
bores 2e, 2f, and adjoining thereat a transition section 2a which
extends conically contracting to the distal nail section 3. The
surface of the securing section 2b has a groove 2g extending
parallel to the inclined bores 2e, 2f. Depending on the fracture,
bone screws can be introduced into the inclined bores 2e, 2f and/or
the groove 2g in order to secure the femur head. For this purpose
an aiming device or a hammering-in tool is preferably used which is
temporarily screwed into the inner thread 2d of the thread section
2c when the locking nail 1 is inserted into the femur in order to
be able to screw in the bone screw with an exact guidance.
[0023] Adjoining at the transition section 2a the distal nail
section 3 extends up to the distal nail end 1b. The centre line 1c
which extends in the middle of the locking nail 1 is illustrated
between the proximal nail end 1a and the distal nail end 1b. The
anterior-posterior plane apE extends corresponding to the plane of
view in accordance with FIG. 1. The distal nail section 3 has a
curvature which extends in this anterior-posterior plane apE and
which is substantially designed corresponding to the antecurvature
of the femur. The curvature of the distal nail section 3 or of its
middle line 1c is preferably designed as a circular segment, with
the radius of curvature R1 amounting to for example 2 meters
depending on the anatomical form of the femur. Transverse bores 3a,
3b, 3d and an oval transverse bore 3c are placed in the distal nail
section 3 for the reception of bone screws.
[0024] In FIG. 1 the lateral-medial plane lmE, which extends
perpendicularly to the plane of view or to the anterior-posterior
plane apE respectively, is also illustrated. The lateral-medial
plane lmE extends corresponding to the plane of view in accordance
with FIG. 2. In FIG. 2 the anterior-posterior plane apE, which
extends perpendicularly to the plane of view or to the
lateral-medial plane lmE, is also illustrated.
[0025] The front view of the locking nail 1 from the direction A in
accordance with FIG. 2 shows the distal nail section 3, which
extends in a straight line in the lateral-medial plane lmE from
this point of view and at which the two, the transition section 2a
and the securing section 2b, having a common curvature with a
constant radius of curvature R2, adjoin. The following thread
section 2c is designed in the illustrated exemplary embodiment to
extend in a straight line, but could however also be designed to
extend curvilinearly and in particular have the same radius of
curvature R2. The partial section 2a, 2b or, respectively, the
centre line 1c which extends in the lateral-medial plane lmE, has a
constant radius of curvature R2 and extends in the axial direction
at least over about a fourth of the total length of the locking
nail 1, and preferably over about a third of its total length.
[0026] The detail view illustrated in FIG. 4 from the direction D
shows a part of the proximal nail section 2, namely the securing
section 2b and the thread section 2c. In the securing section 2b
the openings of the first and second inclined bore 2e, 2f, the
notch 2g and a part of the oval transverse bore 2h can be seen. In
addition the proximal nail section 2 has two notches 21 at the
proximal nail end 1a. The notches 21, the inclined bores 2e, 2f and
the oval transverse bore 2h all extend in the same plane S2. As can
be seen in FIG. 3 the centre lines 2m, 21 of the inclined bores 2e,
2f extend parallel to one another, with the notch 2g also extending
parallel to the inclined bores 2e, 2f in FIG. 4. In further
exemplary embodiments the inclined bores 2e, 2f could also extend
not parallel to one another.
[0027] FIG. 7 shows a plan view from the direction F onto a segment
of the securing section 2b with inclined bores 2e, 2f and notch 2g,
with the direction F extending parallel to the centre lines 2m, 21.
A screw 6 with a centre line 2n is arranged in the ventrally
arranged notch 2g. In the illustrated exemplary embodiment the
centre lines 2m, 21, 2n are spaced to form an equilateral triangle,
with the centre lines 2m, 21 extending through the centre line 1c
of the locking nail 1. The distance between the centre lines 21, 2n
and the centre lines 2m, 2n amounts for example to 8 mm. The
proximal nail section 2 is firmly connected to the femur by one,
two or three screws 6 which are arranged to pass through the two
inclined bores 2e, 2f and the notch 2g. This arrangement of two
inclined bores 2e, 2f and of the notch 2g has the advantage that
the diameter of the proximal nail section 2 can be designed
relatively thin and nevertheless a secure anchoring of the locking
nail 1 by means of bone screws 6 is possible. The locking nail 1
can for example be designed in such a manner that the proximal nail
section 2 has a diameter between 13 and 15 mm and the distal nail
section 3 has a diameter between 9 and 13 mm. A locking nail 1
which is designed to be so thin has the advantage that it requires
only a small opening of the operation field for its implantation.
Thus a lower danger of infection is present during the implanting
due to the small skin opening required. The securing section 2b
with inclined bores 2e, 2f and ventrally arranged notch 2g, in
particular in accordance with the embodiment illustrated in FIG. 4
and FIG. 7, could also be used separately from the other parts 2c,
2a and the distal nail section 3 in a differently designed locking
nail. A securing section 2b of this kind could also be designed to
extend in a straight line or curvilinearly respectively in the
axial direction. FIG. 5 shows a front view of the proximal nail end
1a from the direction E. Starting from the proximal nail end 1a the
locking nail 1 extends along the proximal nail section 2 in a left
curve and extends after the transition to the distal nail section 3
in a downwardly pointing curve. A plane S1 extending in the
direction of view perpendicularly through the distal nail section 3
and the plane S2 extending through the notches 21, the inclined
bores 2e, 2f and the oval transverse bore 2h intersect at an angle
of 78 degrees. The proximal nail section 2 thus has an anteversion
of 78 degrees with respect to the distal nail section 1. This
anteversion is required in order that the inclined bores 2e, 2f and
the transverse bore 2h respectively extend in the direction of the
femur neck or of the femur head respectively when the locking nail
1 is inserted in the femur. The anteversion amounts preferably to
between 75 degrees and 80 degrees, depending on the anatomical form
of the femur. The German term "Antetorsion" is called "anteversion"
in English.
[0028] FIG. 3 shows the locking nail 1 from the direction of view
C, which extends perpendicularly to the plane S2. Relative to the
illustration in accordance with FIG. 2 from the direction of view A
the locking nail 1 is illustrated in accordance with FIG. 3 to be
rotated by 12 degrees about its longitudinal axis. The plane of
intersection through the proximal nail section 2 corresponds to the
plane S2 and extends parallel to the plane of view.
[0029] FIG. 6 shows a section through a further exemplary
embodiment of a distal nail section 3 having a gap 5 which extends
in its longitudinal direction in order to lend a higher elasticity
to the nail section 3.
[0030] The locking nail 1 illustrated in FIGS. 1 to 5 is intended
for a left femur. As a result of the physiological antecurvature
and anteversion of the femur a right and left version of the
locking nail 1 are required.
* * * * *