|Title of Invention||
"DEVICE FOR FIXING A LONGITUDINAL CARRIER TO A BONE FIXING ELEMENT"
|Abstract||The device (1;2) is used for mutually fixing a longitudinal carrier (3) to a bone fixing element (4). Said device consists of a three-dimensional body (5) which is provided with a channel (6) which is open on one side with respect to the channel axis (7) for receiving said longitudinal carrier (3) and a bore (8) which extends fully through the body (5) in a transversal position with respect to the channel axis (7). The channel (6) and the bore (8) at least partially intersect. The bore (8) is conical in form and has a large opening (14) and a small opening (15). It has an inner thread (9). The outer thread (13) of the head (12) of the bone fixing element (4) corresponds to said inner thread.|
|Full Text||The invention relates to a device of the introductory portion of claim 1.
With such devices, it is possible to connect a connecting rod or longitudinal carrier, such as that used in spine surgery, over a bone-fixing element, preferably a bone screw, with the bone and obtain a rigid construct.
US patent 4,920,959 of WITZEL ET AL. discloses an external fixator, which is relatively cumbersome. In particular, the individual clamping elements must be moved onto the longitudinal rods.
The CH-A 632658 discloses an implant for fixing bones, for which the quality of the locking device depends directly on the pretensioned force, which can be realized between the Briden body and the bone. Here also, if the implant is used as a clamp, the individual clamp elements must be moved onto two parallel longitudinal rods. Lateral mounting accordingly is not possible. This may be difficult to realize in the case of a freehand application, particularly a percutaneous and a minimally invasive application, and represents a major disadvantage.
On the other hand, US patent 5,290,288, WO 94/01049 A1 and French patent 2,775,587 A1 also disclose open clamps, which, however, all have the disadvantage that they require an additional element for their fixation. The clamp holding device, that is, the bone screw, must first be fixed in the bone and cannot, freely selectable, be brought in percutaneously, in order only then to be able to position and fix the clamp thereon with the bone screw. For this reason, the longitudinal carrier can be placed on the bone screw only after the clamp has been positioned.
Finally, the WO 95/13754 discloses a clamp, for which a longitudinal rod can be introduced laterally into the open channel of a clamp and clamped there by means of a clamping screw, which can be passed through the clamp. However, the clamping screw has only this one function
and is not constructed as a bone screw, which could fasten the whole construct at the bone. The same is true also for the holding device known from the DE-A 195 34 136.
The devices, known from the art, accordingly are quite complicated and have little flexibility with respect to their field of application.
The invention is to provide a remedy here. It is an object of the invention to provide a device, which has a very simple structure, can be used flexibly and permits a minimally invasive surgical technique.
This inventive object is accomplished with a device, which has the distinguishing features of claim 1.
The advantages of the inventive device are manifold and can be described as follows:
a) it consists of only one part;
b) it can be employed for minimally invasive techniques and does not require a large opening;
c) prestressing between the device and the bone is not necessary in order to ensure the locking
d) it can be use for an external as well as for an internal fixator;
e) the longitudinal carrier can be brought into the device from the very start and pre-shaped and the user must set the bone screw only when he is sure of its position;
f) the position of the individual devices can be selected freely by the users;
g) if a further device is required, it can simply be slipped onto the longitudinal carrier without having to be moved laboriously over the whole length of the longitudinal carrier;
h) before the inventive devices are set, the longitudinal carrier is brought in and gives the surgeon the possibility of being able to determine the screw positions more easily;
i) the possibility exists of setting the fracture over the longitudinal carrier; j) the user can connect and fix the individual fracture parts by a minimally
invasive technique over a construct consisting of a longitudinal carrier
and several inventive devices by means of angularly stable head
locking screws; and k) the inventive device can be used not only in the spinal column area, but
also in other osteosynthetic application fields.
The inventive device enables a longitudinal carrier and a standard head-locking screw, corresponding to the recess, to be accommodated. When the head-locking screw is tightened, it locks the longitudinal carrier in the inventive device.
The borehole in the device appropriately has a conical angle ranging from 5° to 25° and preferably from 8° to 15°.
The inventive devices, realized in the form of clamps, may be realized in two different embodiments, a type A and a type B. They differ therein that one can be mounted from above (type A) and the other from below (type B) on the longitudinal carrier (connecting rod). The locking principle for the two types is the same. In the case of type A, the conical borehole tapers towards the channel and the smaller opening of the borehole is on the same side of the body as the channel. This results in the advantage that the device can be slipped laterally onto the already mounted longitudinal rod. In a case of type B, the conical borehole expands in the direction of the channel and the larger opening of the borehole is on the same side of the body as the channel. This results in the advantage that the longitudinal carrier can be introduced laterally into the already mounted device.
In the case of a special embodiment, the device additionally has a bone fixation element, preferably in the form of a bone screw, with a tip, which is suitable for introduction into the bone, a threaded shaft and a head,
suitable for manipulating the screw. This permits the setting of the bone fragments via the bone screw.
In a case of a further embodiment, the head of the bone fixation element has an external thread, which preferably corresponds to the internal thread of the borehole. This guarantees the least possible material abrasion during the fixation. The pitch of the external thread advisably is 0.1 to 3.0 mm and preferably 0.25 to 1.50 mm.
In the case of a further embodiment, the head of the bone fixation element tapers conically towards the tip. The conically tapering head advisably has a conical angle ranging from 5° to 25° and preferably from 8° to 15°.
In the case of a special embodiment, a device of type A is combined with a device of type B. Such a combination has the advantage that it forms a rigid frame together with the treated bone.
A general and a special method of operation for the inventive device are described briefly below.
General Method of Operation:
A) To begin with, the longitudinal carrier is introduced through a stab incision into the region of the patient that is to be treated and pushed percutaneously into the desired position;
B) the surgeon can now control the contour of the longitudinal carrier and correct it easily;
C) if the control of the longitudinal carrier is satisfactory, the desired number of clamps (inventive devices) can be introduced percutaneously through corresponding stabbed incisions and mounted laterally directly on the rod;
D) the angularly stable head-locking screws are now screwed in to the
boreholes of the clamps, but not yet tightened;
E) if the setting is satisfactory, the angularly stable head locking screws
can be tightened definitively, so that the construct, formed from the
longitudinal carrier, the clamps and the bone screws, becomes rigid
and the fracture is fixed.
Special Method of Operation
1. The inventive device (clamp) of type B is positioned relative to the desired bone part;
2. A head-locking screw is screwed through the conical borehole of the clamp of type B to a predetermined depth, so that the clamp is pre-fixed;
3. The longitudinal carrier is molded to meet the anatomical requirements;
4. The longitudinal carrier is inserted in the open channel of the already pre-mounted clamp of type B;
5. The head-locking screw is now tightened completely in the clamp of type B, so that the longitudinal carrier is fixed at the clamp;
6. The fracture is set over the longitudinal carrier with a suitable setting instrument;
7. The set bone fragments are fixed by means of the clamps of type A or type B;
8. The bone fixation construct optionally is supplemented with clamps of type A or type B.
The invention and further developments of the invention are explained in even greater detail in the following by means of the partially diagrammatic representations of several examples. In the drawing,
Fig. 1 shows an exploded representation of a bone fixation device with a longitudinal carrier, two different types of the inventive device (clamps) and two bone screws;
Fig. 2 shows a view of an inventive device (clamp) of type B;
Fig. 3 shows an elevation view of the device of Fig. 2;
Fig. 4 shows a view of an inventive device (clamp) of type A; and
Fig. 5 shows an elevation view of the device of Fig. 4.
In Fig. 1, two embodiments of the device 1; 2, which connect the longitudinal carrier 3 with a bone fixation element 4, are shown. The two embodiments of the device 1; 2 differ essentially in the construction of the channel 6 for accommodating the longitudinal carrier 3. For the first embodiment (type A), the channel 6 is open towards the lower surface 16 of the body 5, which is directed towards the segment of the bone fixation element 4, which is constructed here as a threaded shaft 11. For the second embodiment (type B), the channel 6 is open towards the upper surface 17 of the body 5, adjoining the head 12 of the bone fixation element 4. At the lower surface 16 of the body 5 (type A) or at the upper surface 17 (type B), transversely to the channel axis 7, the open surface of the channel 6 has a width B, which is larger than or equal to the diameter of the longitudinal carrier 3, so that a longitudinal carrier 3 can be introduced transversely to the channel axis 7 from below (type A) or from above (type B) into the channel 6.
For this embodiment, the bone fixation agent 4 is constructed as a bone screw 18, and comprises a threaded shaft 11, which can be screwed into a bone, especially a pedicle, with a tip 10 and a conical head 12, the end of the conical head 12, having a smaller diameter, being directed towards the threaded shaft 11. A conical borehole 8, complementary to the head 12 of the bone fixation element 4, passes through the body 5 from the upper surface 17
to the lower surface 16, the longitudinal axis 19 of the borehole 8 being skew with respect to the axis 7 of the channel. For both embodiments, type A and type B of the device 1; 2, the larger opening 14 of the borehole 8 discharges into the upper surface 17 and the smaller opening 15 into the lower surface 16. Especially for the embodiments of type A and type B of the device 1; 2 shown here, the longitudinal axis 19 of the borehole 8 is perpendicular to the channel axis 7, there being a distance X between the longitudinal axis 19 and the channel axis 7. The dimensions of this distance X are such, that the conical borehole 8 intersects the channel 6, the distance X being larger than the sum of the radius R of the longitudinal carrier 3 and the radius r of the threaded shaft 11 of the barren fixation element 4. With that, it can be achieved that, even when the longitudinal carrier 3 is introduced into the channel 6, the threaded shaft 11 of the bone fixation element 4 can be passed through the borehole 8 and screwed into a bone, until the conical head 12 of the bone fixation element 4, which is complementary to the borehole 8, has been introduced in two the borehole 8 to such an extent, that it is in contact with the longitudinal carrier 3 and the longitudinal carrier 3 can be fixed in the channel
6 by tightening the bone fixation element 4.
For both types A; B, of the device 1; 2, the channel 6 embraces a concave sidewall 20, which is remote from the borehole 8 and secures a longitudinal carrier 3, which has been placed in the channel 6, against displacements parallel to the longitudinal axis 19 of the borehole 8. When the bone fixation element 4 is tightened, the longitudinal carrier 3, inserted in the channel 6, is pressed by the conical head 12 transversely to the channel axis
7 against the concave side wall 20 of the channel 6 and fixed in the channel 6.
Furthermore, the borehole 8 is provided with an internal thread 9 and the head
12 of the bone fixation element 4 is provided with a complementary external
thread 13, so that, when a bone fixation element 4 is tightened, stable locking
between the bone fixation element 4, the body 5 and the longitudinal carrier 3
can be brought about.
1. The device (1; 2) for mutually fixing a longitudinal carrier (3) and a bone
fixation element (4), the device consisting of a three-dimensional body (5),
which has a channel (6) with an axis (7), which is open at one side for
accommodating the longitudinal carrier (3), as well as a borehole (8), which
extends transversely to the channel axis (7) and passes through the body
(5) completely, the channel (6) and the borehole (8) penetrating one
another at least partly, characterized in that
A) the borehole (8) is constructed conically with a larger openings (14), and a smaller opening (15) and
B) the borehole (8) has an internal thread (9),
2. The device (1; 2) as claimed in claim 1, wherein in the borehole (8) has a conical angle ranging from 5° to 25°.
3. The device (1; 2) as claimed in claim 1 & 2, wherein the borehole (8) has a conical angle ranging from 8° to 15°,
4. The device (1; 2) as claimed in any one of the claims 1 to 3, wherein
A) the conical borehole (8) tapers towards the channel (6) and
B) the smaller opening (15) of the borehole (8) is on the same side of
the body (5) as the channel (6),
5. The device (1; 2) as claimed in above claims, wherein
A) the conical borehole (8) expands towards the channel (6) and
B) the larger opening (14) of the borehole (8) is on the same side of the body (5) as the channel (6),
6. The device (1; 2) as claimed in claim 1, wherein it has additional bone
fixation element (4), preferably in the form of a bone screw, with a tip (10), suitable for introduction into the bone, a threaded shaft (11) and a head (12) suitable for manipulating the screw,
7. The device as claimed in claiml & 6, wherein the head (12) of the bone fixation element (4) has an external thread (13), which preferably corresponds to the internal thread (9),
8. The device as claimed in claim 1 & 7, wherein the pitch of the external thread (13) is between 0.1 and 3.0 mm and preferably between 0.25 and 1.50 mm,
9. The device as claimed in claims 6 to 8, wherein the head (12) of the bone fixation element (4) tapers conically towards the tip (10),
10. The device as claimed in claim 1 & 9, wherein the head (12), tapering
conically, has a conical angle ranging from 5° to 25° and preferably from 8° to 15°,
11. The device as claimed in above claims wherein a longitudinal carrier (3)
has at least one device of claim 4, as well as at least one device of claim
|Indian Patent Application Number||237/DELNP/2006|
|PG Journal Number||18/2013|
|Date of Filing||13-Jan-2006|
|Name of Patentee||SYNTHES GMBH|
|Applicant Address||EIMATTSTRASSE3,CH-4436 OBERDORF, SWITZERLAND|
|PCT International Classification Number||A61B 17/70|
|PCT International Application Number||PCT/CH2003/000516|
|PCT International Filing date||2003-07-29|