Source: https://patents.google.com/patent/EP0270704A1/en
Timestamp: 2020-08-04 12:27:34
Document Index: 280939922

Matched Legal Cases: ['art 10', 'art 10', 'art 11', 'art 10', 'art 11', 'art 10', 'art 10', 'art 10', 'art 10', 'art 11', 'art 11', 'art 11', 'art 11', 'art 11']

EP0270704A1 - Anchoring element for fastening an osteosynthesis plate to a bone - Google Patents
EP0270704A1
EP0270704A1 EP86117360A EP86117360A EP0270704A1 EP 0270704 A1 EP0270704 A1 EP 0270704A1 EP 86117360 A EP86117360 A EP 86117360A EP 86117360 A EP86117360 A EP 86117360A EP 0270704 A1 EP0270704 A1 EP 0270704A1
EP0270704B1 (en
1986-12-12 Application filed by Aesculap AG, Aesculap Werke AG filed Critical Aesculap AG
210000000988 Bone and Bones Anatomy 0.000 title claims abstract description 37
In order to enable a fixation element for fixing an osteosynthesis plate provided with bores to a bone to be securely fixed to an osteosynthesis plate even if materials are used for the fastener which are less strong than metallic implant materials, it has been proposed that the fixation element be a dowel (1 ) with a widened head (3) and a continuous longitudinal bore (6) widening at its end facing away from the head (3) as well as a clamping pin (2) which has a first shaft part (10) which passes through the longitudinal bore (6) and comprises an expanding second clamping part (11) which, when the clamping pin (2) is inserted into the longitudinal bore (6), bears against the wall of the expanded part (8) of the longitudinal bore (6) and thereby the dowel (1) in this end region expands.
The invention relates to a fastening element for fixing an osteosynthesis plate provided with bores to a bone.
Osteosynthesis plates are used to connect bone parts, which are normally attached to the bone parts to be connected with screws. It is known to produce the osteosynthesis plates and the screws from special austenitic implant steel. This enables the necessary strength properties to be achieved, but it is disadvantageous that, on the one hand, due to the hardness of the plates, individual adaptation of the plates to the implant is difficult and that, on the other hand, these implants have to be removed from the body again after a suitable period of time.
In fact, they are already used to manufacture Implanta ten usable substances known that are broken down in the body and reabsorbed by the body after some time, so that removal is not necessary. However, such implant materials generally do not have the same strength as the materials used for osteosynthesis, so that vascular clips or pins for the reduction of cartilage fractures have been produced with such materials, but these materials were not suitable for conventional osteosynthesis processes. This applies in particular to the fastening elements with which osteosynthesis plates are attached to the bone. If these are formed in the conventional form as screws, it is not possible to screw them into the bone, since the screw heads tear off when they are screwed in.
It is an object of the invention to provide a fastening element for osteosynthesis plates, which allows a safe and permanent fixation of an osteosynthesis plate to the bone even when using a less solid material.
This object is achieved according to the invention in a fastening element of the type described at the outset in that it has a dowel with a widened head and a continuous longitudinal bore widening at its end facing away from the head and a tensioning pin which has a first shaft part which fits through the longitudinal bore and comprises an expanding second clamping part which, when the clamping pin is inserted into the longitudinal bore, lies against the wall of the expanded part of the longitudinal bore and thereby widens the dowel in this end region.
The dowel thus has the shape of a screw on the outside, so that it can be inserted into a bore in the osteosynthesis plate by placing the widened head. However, the part protruding from the osteosynthesis plate into the bone does not have an external thread, but is anchored in the bone by widening the free end. This expansion takes place by means of a clamping pin which is pushed or pulled into the longitudinal bore for expansion, so that the clamping part forces the wall of the expanded part of the longitudinal bore apart and thereby expands the dowel at the free end as a whole.
It has been found that an excellent fixation of osteosynthesis plates with clamping elements of this type is possible, so that materials which are less strong than the conventionally used metal implants can be used to produce these clamping elements. Nevertheless, an adequate fixation of the osteosynthesis plates on the bone can be achieved. This leads to the fact that the clamping elements described can also be produced from resorbable plastics, for example from polylactite. If such materials are used both for the osteosynthesis plate itself and for the fastening elements, these implants dissolve in the body after a certain time and are reabsorbed by the body, so that a reoperation for removing the implants becomes superfluous.
In order to facilitate the widening of the free end region of the dowel, it can be provided in a preferred embodiment that the dowel is in the region of the widened longitudinal Hole is slotted in the longitudinal direction. It is also advantageous if the dowel carries radially projecting retaining elements at its expandable end, which can claw into the surrounding bone tissue.
In a preferred embodiment it is provided that the shaft part of the clamping pin is so long that it emerges from the opposite end of the longitudinal bore before the clamping part rests on the widened inner wall of the longitudinal bore. This makes it possible to grasp the shaft part protruding from the head of the dowel with a tool and pull it out of the dowel while pressing the head against the bone until the tensioning part of the clamping pin has widened the free end of the dowel in the desired manner . This can be done with a suitable tool.
It is particularly advantageous if a predetermined breaking point is arranged between the shaft part and the clamping part, which is preferably formed by a circumferential notch. The clamping process of the clamping pin is ended in that the shaft part tears off from the clamping part pressed firmly into the dowel. This not only leads to the fact that the clamping element is always drawn into the dowel with a predetermined force, it also means that the clamping part remains inside the dowel without parts of the clamping pin protruding from the dowel. This ensures that the tensioning part remains in its tensioned position and cannot be accidentally pushed back again. In addition, there are no parts protruding from the dowel itself that could damage the surrounding tissue.
In a special embodiment it is provided that the tensioning part is provided on its outer jacket with circumferential projections and that the dowel in the contact area of the inner wall of the longitudinal bore on the tensioning part has projections which come into operative connection with the projections on the tensioning part. The projections can be ribs or shoulders that run in the circumferential direction, for example, both the tensioning part and the inner wall of the bore can be provided with cross corrugation. This results in a positive locking between the clamping part and the inner wall of the longitudinal bore in the longitudinal direction of the bore, which prevents the clamping part from accidentally sliding out of the dowel again after being pulled into the dowel.
Fastening elements of the type described are known per se, for example, from US Pat. No. 3,708,883. There they are used as holding elements that can be inserted into the jaw, and an artificial tooth is screwed onto the threaded parts protruding from the jaw. However, this very special use cannot suggest the use of clamping elements of this type instead of the conventional screws for fixing osteosynthesis plates to bones.
The following description of preferred embodiments of the invention serves in conjunction with the drawing for a more detailed explanation. Show it:
Figure 1: a side view of a partially broken thigh bone with an osteosynthesis plate which is fastened to the bone fragments by means of fastening elements according to the invention;
Figure 2: a bone connection with two plate-shaped bone elements;
Figure 3 is a partial sectional view of an anchor of a fastener;
Figure 4 is a side view of a clamping pin of a fastener;
FIG. 5: a sectional view of a dowel with inserted clamping pin before clamping;
Figure 6: a view similar to Figure 5 after tensioning the clamping pin with torn shaft part and
FIG. 7: an enlarged detailed view corresponding to section A in FIG. 6.
The fastener shown in Figures 3 to 6 in detail comprises a dowel 1 (Figure 3) and a clamping pin 2 (Figure 4). The dowel 1 has a lenticular head 3, as is known per se from screws. This is followed by a shaft 4, which, in contrast to bone screws, does not have an external thread, but rather in the region of its free end sawtooth-like circumferential ribs 5, which act as retaining elements. egg ne longitudinal bore 6 passes through the entire dowel 1. This is cylindrical in the area 3 adjacent the head 3, in the area of the dowel 1 facing away from the head, the longitudinal bore 6 widens in the direction of the end of the dowel 1, so that a conical widening clamping range 8 arises. The dowel 1 is provided with two diametrically opposed longitudinal slots 9 up to the starting point of the head 3, which extend into the longitudinal bore 6.
The clamping pin 2 comprises a cylindrical shaft part 10, the outer diameter of which is selected such that it is smaller or at most equal to the inner diameter of the cylindrical region 7 of the longitudinal bore 6. This cylindrical shaft part 10 is followed by a conically widening clamping part 11, the conicity of which corresponds to that of the clamping region 8 of the longitudinal bore 6, as long as the longitudinal bore 6 has not yet been widened in this region. In the transition area between the cylindrical shaft part 10 and the conical clamping part 11, the shaft part 10 is weakened by a circumferential notch 12, so that a predetermined breaking point is created in this area.
Both the dowel 1 and the clamping pin 2 preferably consist of a resorbable material, in particular of polylactite. However, other plastic materials can also be used.
The fastening elements described are used for fastening osteosynthesis plates 13 to a bone 14. The osteosynthesis plates 13 can basically consist of any material, preferably these osteosynthesis plates also consist of a material that is resorbable in the body, for example polylactite. The osteosynthesis plates can take all conventional forms, preformed osteosynthesis plates or those which are cut from a plate during operation, shaped by sawing or cutting, drilled and, if necessary, adapted to the contour of the bone by the action of heat can be used.
To attach such an osteosynthesis plate to a bone, a dowel 1, into which a clamping pin 2 is inserted in the manner shown in FIG. 5, is extended through an opening 15 in the osteosynthesis plate 13, as is known per se from bone screws. The dowel of the fastener is then inserted into a corresponding hole in the bone until the osteosynthesis plate 13 is firmly against the bone.
The tensioning pin 2 is so long that the tensioning pin 2 inserted into the dowel but not yet tensioned protrudes from the head 3 of the dowel 1 (FIG. 5). To fix the dowel in the bone, the shaft part 10 protruding from the head 3 is grasped by means of a suitable pliers-shaped tool and pulled out of the dowel, at the same time the head of the dowel being pressed firmly against the osteosynthesis plate, which at the same time is firmly attached to the bone is created. The conical shaft part 10 is drawn into the conically widened clamping area 8 in the longitudinal bore 6 and thereby expands the free end part of the dowel 1. This expansion is due to the longitudinal slots 9 relieved (Figure 6). The circumferential ribs 5 claw into the surrounding cancellous bone tissue and fix the dowel securely in the bone.
When a certain tensile force is exceeded, the shaft part 10 tears off in the area of the Kerby 12, which acts as a predetermined breaking point, so that the shaft part can be pulled out of the dowel 1 (FIG. 6). Then only the clamping part 11 remains in the dowel, which ensures that the dowel is fixed in the spread position and fixed in the bone.
The tensioning part 11 carries on its outer jacket 16 a horizontally circumferential corrugation, so that a plurality of rib-shaped projections 17 that run parallel to one another are formed there. In the same way, the inner wall of the longitudinal bore 6 is corrugated, so that it also carries horizontally circumferential projections 18. The projections 17 and 18 are designed so that they engage in a complementary form-fitting manner when the clamping part 11 is pulled into the longitudinal bore 6. This results in an axial fixation of the clamping part 11 in the longitudinal bore 6, that is, an unintentional displacement of the clamping part 11 out of its clamping position is no longer possible.
In the exemplary embodiment in FIG. 1, the entire part of the dowel provided with circumferential ribs 5 is located inside the bone. In the embodiment of FIG. 2, in which relatively thin, plate-shaped bone parts are to be connected to one another, for example parts of a skull or face bone, the parts of the dowel 1 provided with circumferential ribs 5 step on that of the osteosynthesis plate the opposite side from the bone. In this part emerging from the bone, the dowel 1 is spread out, so that a secure fixing of the dowels in the bone is also possible in this way.
The fastening elements described hold the osteosynthesis plate in the bone so securely that materials can be used which have lower strength values than conventional implant materials. This is advantageous on the one hand if resorbable materials are used, and on the other hand plastic materials can also be used which do not cause any undesired disturbances, for example in computer tomograms or in nuclear magnetic resonance tomograms.
1. Fastening element for fixing an osteosynthesis plate provided with holes on a bone, characterized in that it has a dowel (1) with a widened head (3) and a continuous longitudinal bore (6) widening at its end facing away from the head (3). and a clamping pin (2) which comprises a first shaft part (10) which passes through the longitudinal bore (6) and a widening second clamping part (11) which, when the clamping pin (2) is inserted into the longitudinal hole (6) on the Wall of the expanded part (8) of the longitudinal bore (6) abuts and thereby widens the dowel (1) in this end area.
2. Fastening element according to claim 1, characterized in that the dowel (1) is slotted in the longitudinal direction in the region of the widened longitudinal bore (6).
3. Fastening element according to one of the preceding claims, characterized in that the dowel (1) its expandable end carries radially projecting retaining element (5).
4. Fastening element according to one of the preceding claims, characterized in that the shaft part (10) of the clamping pin (2) is so long that it emerges from the opposite end of the longitudinal bore (6) before the clamping part (11) on the expanded inner wall the longitudinal bore (6) rests.
5. Fastening element according to claim 4, characterized in that a predetermined breaking point is arranged between the shaft part (10) and clamping part (11).
6. Fastening element according to claim 5, characterized in that the predetermined breaking point is formed by a circumferential notch (12).
7. Fastening element according to one of the preceding claims, characterized in that the dowel (1) and the clamping pin (2) and / or the osteosynthesis plate (13) consist of a material that is resorbable by the body.
8. Fastening element according to one of the preceding claims, characterized in that the clamping part (11) on its outer jacket (16) with in the circumferential direction running projections (17) and that the dowel (1) in the contact area of the inner wall of the longitudinal bore (6) on the clamping part (11) with the projections (17) on the clamping part (11) has projections (18) which come into operative connection.
ES86117360T ES2008852B3 (en) 1986-12-12 1986-12-12 Fixing element for the immobilization of an osteosynthesis plate in a bone
EP0270704A1 true EP0270704A1 (en) 1988-06-15
EP0270704B1 EP0270704B1 (en) 1989-04-26
US20190223926A1 (en) 2019-07-25 Orthopedic Fixation Screw With Bioresorbable Layer
ES2342828T3 (en) 2010-07-15 Spinal fixing device.