Source: https://patents.google.com/patent/ES2453196T3/en
Timestamp: 2019-12-10 11:05:19
Document Index: 714457169

Matched Legal Cases: ['art 103', 'art 5', 'art 5', 'art 5', 'art 5', 'art 5', 'art 5', 'art 22', 'art 22', 'art 5', 'art 5', 'art 5', 'art 22']

ES2453196T3 - Bone anchoring device - Google Patents
ES2453196T3
ES2453196T3 ES06017651.8T ES06017651T ES2453196T3 ES 2453196 T3 ES2453196 T3 ES 2453196T3 ES 06017651 T ES06017651 T ES 06017651T ES 2453196 T3 ES2453196 T3 ES 2453196T3
ES06017651.8T
2006-08-24 Application filed by Biedermann Motech GmbH and Co KG filed Critical Biedermann Motech GmbH and Co KG
2006-08-24 Priority to EP06017651.8A priority Critical patent/EP1891904B1/en
2014-04-04 Publication of ES2453196T3 publication Critical patent/ES2453196T3/en
Bone anchoring device comprising an anchoring element (2, 2 ') that includes a rod (3) to be fixed in a bone or a vertebra and a receiving part (5, 5') connected to the rod; a rod (20, 20 ') for connecting at least two anchoring elements; wherein the receiving part (5, 5 ') comprises a receptacle (5a, 11) for housing said rod; a blocking element (50, 29) that cooperates with the receiving part to secure the rod in the receptacle, where the blocking element comprises a first blocking element (30) and a second blocking element (31); a filling piece (60, 22) arranged between the blocking element (50, 29) and the rod (20, 20 ') to exert pressure on the rod in order to block it in the receptacle, the filling part comprising a contact surface (61, 25) with the rod that contacts a part of said rod, the shape of the rod contact surface adapting to the shape of the rod segment characterized in that said rod has at least one part of the same a tubular shape (31) and the filling piece (22) is connected either with the first blocking element or with the second blocking element.
Bone anchoring device.
The invention relates to a bone anchoring device comprising a bone anchoring element and a rod for connecting at least two bone anchoring elements, where the rod has, at least in a part thereof, a tubular structure.
Fig. 12 shows a known polyaxial bone screw 100 with a threaded element 101 having a bone thread and a spherical segment-shaped head 102 pivotably held in a receiving part 103. The receiving part has a receptacle for accommodating a rod 104. Between the head 102 and the rod there is provided a pressure element 105 that can slide in the receiving part. An inner screw 106 is used to fix the rod in the receiving part and to exert pressure on the head by means of the rod and the pressure element in order to fix the head. From US 2005/0154390 A1, for example, a flexible rod of tubular structure is known to stabilize the spine. When a tubular rod is used together with the known polyaxial bone screw as described with reference to Fig. 12, the load acting on the rod when the inner screw is tightened can deform the tubular rod as shown schematically in the Fig. 13. This will affect the properties of the rod.
US 2004/0138660 A1 describes a locking cap system for blocking a rod that is made from a completely metal cylinder for a bone screw receiving body. The locking hood system includes an inner and an outer locking element. The outer locking element is a nut-like element to which the inner locking element is rotatably connected. The inner locking element has, on its side facing the rod, a deformable ring-shaped contact element that comes into contact with the rod. By tightening the outer locking element, the deformable contact element is deformed, providing feedback to the surgeon and allowing him to determine if the locking cap system is fixed to the necessary extent.
Document FR 2 810 533 describes a bone anchoring device with a rod made from a complete cylinder. A locking hood system comprises a rotatably supported element that presses from above on the rod. The shape of the rod in contact with the surface of said element is adapted to the contour of the rod.
EP 1 604 617 A describes a bone anchoring device according to the preamble of the claim
An object of the invention is to provide a bone anchoring device that is suitable for dynamic stabilization and that comprises an improved fixation of the tubular part of the rod.
This objective is achieved with a bone anchoring device according to claim 1. Other developments are indicated in the dependent claims.
The bone anchoring device provides a fixation of a tubular rod where the deformation of the tubular rod is minimized even in the case of a great tightening force in the fixation.
Other features and advantages of the invention will be apparent and will be better understood in reference to the following detailed description of embodiments along with the accompanying figures.
Fig. 1: exploded view of the bone anchoring device according to a first example.
Fig. 2: perspective sectional view of the bone anchoring device of Fig. 1 in assembled and fixed state.
Fig. 3a and 3b: schematically show the fixing by tightening of the rod under the action of a lower and greater clamping force F.
Fig. 4: Exploded view of the bone anchoring device.
Fig. 5: A perspective of the bone anchoring device of Fig. 4 in assembled state.
Fig. 6: Sectional view of the bone anchoring device in assembled and fixed state as shown in Fig. 4.
Fig. 7: A perspective of the filling part that is part of the bone anchoring device of Fig. 4.
Fig. 8: side view of the filling piece in the direction of the rod axis.
Fig. 9: side view of the rotated filler 900.
Fig. 10: top view of the filling piece.
Fig. 11: a perspective of the filling part seen from below.
Fig. 12: A schematic cross-sectional view of a conventional polyaxial bone screw with a rod.
Fig. 13: a schematic view of the tightening of the rod in case of using a conventional polyaxial screw and a tubular rod.
Figs. 1 and 2 show a bone anchoring device 1 according to a first example. The bone anchoring device 1 includes a monoaxial bone screw 2 and a tubular rod 20. The bone screw 2 has a rod 3 with a bone thread for anchoring to the bone, a tip at one end (not shown) and a receiving part 5 at the opposite end. The receiving part 5 comprises a receptacle 5a essentially U-shaped to receive the rod 20. Through this receptacle two free pins 5b, 5b 'are formed which have an internal thread 5c to receive a locking element to secure the rod 20 in the receptacle. The locking element is an inner screw 50 that can be screwed between the pins. The thread can be a flat thread to prevent broadening of the pins when the inner screw is tightened. However, any other type of thread can be used, such as a metric thread, a sawtooth thread or a negative angle thread. In assembled state the rod 20 rests on the bottom of the receptacle 5a.
A filling piece 60 is provided between the inner screw 50 and the rod. The outer contour of the filling piece 60, seen from the top, is essentially rectangular, with two opposite long straight sides and two opposite short lakes curved towards the outside. The filling piece has a contact surface 61 of the rod on its side facing the rod, whose shape is adapted to the shape of the rod surface. In the embodiment shown, the rod 20 has a cylindrical shape. Thus, the contact surface 61 of the rod is formed by a recess in the form of a cylindrical segment in the filling piece. The size of the contact surface 61 of the rod is selected to provide a desired load distribution when the rod is pressed between the filling piece and the bottom of the U-shaped receptacle 5a. The surface 62 opposite the contact surface 61 of the rod is essentially flat, with a cylindrical projection 63 in the center. The cylindrical projection 63 can be inserted into a corresponding cylindrical bore 51 of the inner screw 50 provided on the lower side of the inner screw. With this, the inner screw can rotate with respect to the filling piece. At its free end, the projection 63 may have an protruding edge 64 cooperating with a corresponding circular recess in the inner screw, so that the filling piece is rotatably supported on the inner screw. The inner screw also has a recess 52 on the opposite side for assembly with a tool.
The rod 20 is shaped like a cylindrical tube.
All parts of the bone anchoring device are made of a biocompatible material, for example a metal such as titanium or an alloy of metals or a biocompatible plastic material.
In use, at least two bone anchoring elements are anchored in two vertebrae or in two bone parts that must be stabilized with the rod. Then the rod is inserted into the receiving parts. Then the inner screw is inserted with the filler and tightened.
As can be seen in Fig. 3a and 3b, when the filling piece presses with its contact surface 61 against the rod surface it is minimized or even a possible deformation of the tubular rod is avoided. The homogeneous distribution of the load on the surface of the rod prevents its deformation.
As shown in Figs. 4 and 6, the bone anchoring device 1 'according to one embodiment is of the polyaxial type and includes a bone anchoring element 2' in the form of a bone screw with a rod 3 including a bone thread and a tip (not shown) as well as a head 4. In the example shown, head 4 has a spherical segment shape. A recess (not shown) for assembly with a screwdriver is provided at the free end of head 4.
The bone anchoring device further comprises a receiving part 5 'having a first end 6 and an opposite second end 7, a central axis C that crosses the planes defined by the first and second ends respectively and a coaxial bore 8 extending from the first end some distance from the second end. At the second end 7 there is provided an opening 9 whose diameter is smaller than the diameter of the hole 8. Adjacent to the opening 9 a spherical section 10 forming a head seat 4 is provided. The section forming the seat may have other shapes, for example conica.
The receiving part 5 'has an essentially U-shaped receptacle 11 that begins at the first end 6 and extends some distance from the second end 7 to receive the rod 20'. Two free pins 12, 13 are formed by the U-receptacle. In addition, the receiving part 5 'comprises an internal thread 14 on the pins 12, 13.
The bone anchoring device 1 further comprises a pressure element 15. In the embodiment shown, the pressure element 15 has an essentially cylindrical design with an outer diameter that is only slightly smaller than the inner diameter of the hole 8, to allow the element Pressure 15 is inserted into hole 8 and moves in the axial direction. The pressure element 15 comprises on its lower side facing the second end 7 a spherical recess 16 whose radius essentially corresponds to the radius of the head 4 of the bone screw. On the opposite side, an essentially U-shaped recess 17 is provided whose depth is greater than the diameter of a rod 20. The rod 20 connects at least two bone screws. By means of the U-shaped recess 17 two free pins 18, 19 are formed that extend above the surface of the rod 20 when it is seated in the pressure element 15. The pressure element 15 further comprises a coaxial bore 21 to allow access to the head of screw 4 with a screwdriver.
The bone anchoring device further comprises a filling piece 22 that is described in more detail in Figs. 7 to 11. In the embodiment shown, the filling piece is sized so that it is slidable in the U-shaped recess 17 of the pressure element. It also has two opposite flat side walls that face the inner side of the pins 18, 19 of the pressure element 15. In addition, it has two opposite rounded sides 24, 24 '. On its lower side, the filling piece 22 comprises a receptacle 25 for housing the rod 20. In the embodiment shown, the rod 20 is a cylindrical rod and the receptacle 25 is adapted to the rod 20 in shape and size. The depth of the receptacle is less than or equal to the radius of the rod 20, so that the filling piece 22 can exert pressure from above on the surface of the rod 20. The filling piece 22 includes, on the side opposite to the receptacle 25 , an essentially flat surface 26. Furthermore, it comprises a coaxial bore 27. Around the coaxial bore there is provided a contact surface 28 that projects from the flat surface 26. The contact surface has, for example, an annular shape.
The dimension of the filling piece 22 in this embodiment shown in Fig. 4 can be such that, in the assembled state, when the rod 20 rests in the U-shaped recess 17 of the pressure element 15 and the part has been placed of filling 22 at the top of the rod, the surface 26 is located slightly below the final surface of the pins 18, 19 of the pressure element 15.
The bone anchoring device comprises a locking system 29 for fixing the rod and the head. The locking system 29 consists of a first locking element 30 in the form of an internal screw that cooperates with the internal thread 14 of the receiving part 5 '. As shown in Fig. 6, the cooperating threads are, for example, flat threads. However, any other form of thread is possible. The first locking element 30 comprises a coupling structure 32 for assembling a screwdriver and a coaxial threaded bore 33 to receive the second locking element 31 in the form of a fixing screw. The second locking element 31 also comprises a coupling structure 34 for assembly with a screwdriver. On the side facing the rod a projection 35 is formed whose shape is such that it fits inside the hole 27 of the filling piece 22 and allows to provide a rotational movement between the filling piece 22 and the second locking element 31.
The dimensions of the locking system 29, the pressure element 15 and the filling part 22 are such that, in the assembled state as shown in Fig. 6, the first locking element 30 contacts the upper surface of the free pins 18, 19 of the pressure element but does not contact the filling piece 22. The second blocking element 31 contacts the contact surface 28 of the filling part 22, but does not contact the pressure element. With this, the rotating position of the head 4 in the receiving part and the position of the rod in the anchoring device can be locked separately.
Preferably, the material from which the bone anchoring element is made is a physiologically compatible material, such as titanium or a titanium alloy.
The rod 20 'has a tubular shape with a helical recess 40 in at least a part of its wall. The helical recess 40 provides elasticity against axial and flexural forces and, in specific applications, also against torsional forces. The characteristics of the helical recess 40, for example the pitch, the width of the recess, the exact profile of the spiral and other parameters, may vary according to the desired flexible properties of the rod 20 '. In addition, the rod 20 'can have a core 41 with a diameter smaller than the inside diameter of the tube. The core 41 may be designed for sliding into the tube. The core material 41 and its particular diameter or shape are selected so that the desired elastic properties of the rod 20 'are achieved. For example, the core 41 may be provided to reinforce the stiffness of the flexible tubular rod 20 ', for example to prevent bending.
The tubular rod 20 'can be made of the same material as the bone anchoring element or other material. For example, the rod may be made of a material that exhibits greater elasticity per se. This material can be a plastic material or an alloy with shape memory and / or with superelastic properties.
In use, the bone screw 2, the receiving part 5 'and the pressure element 15 can be pre-assembled, so that the head 4 is rotatably held in the receiving part 5' and the pressure element 15 is held in a loose and safe way against a rotation within the receiving part 5 '. Pre-assembled bone anchoring elements are screwed into adjacent vertebrae of a mobile spinal segment. The rod 20 'is then inserted into the receiving part so that it rests on the pressure element and at the bottom of the U-shaped receptacle 11 of the receiving part. The second filling piece 22 can be loosely connected to the second locking element 31 by means of the projection 35 of the second blocking element extending through the hole 27 of the filling piece. Then the pre-assembled locking system 29 is inserted in the receiving part together with the filling piece 22. Finally, the angular position of the receiving part is adjusted relative to the bone screw and the head 4 of the bone screw is fixed in this position, tightening down the first locking element 30. Because the first locking element 30 contacts on its lower surface with the upper surface of the pins 18, 19 of the pressing element without touching the filling piece 22, the head can be fixed using the pressure element 15. Next, the position of the rod 20 is adjusted. Finally, the second locking element 31 is tensioned downwards until it presses on the contact surface 28 of the filling piece. The frictional forces acting between the pressure element and the rod, respectively, hold the rod in place.
The homogeneous distribution of the load on the surface of the rod provided by the filling piece prevents deformation. For this reason a core 41 that moves inside the tubular rod is not blocked by the deformation of the rod.
In another modification, the blocking system comprises only a single blocking element. In this case, the pressure element 15 does not have pins 18, 19 that extend above the surface of the rod. The filling piece presses on the rod and the rod presses on the pressure element so that the head and the rod are fixed simultaneously.
Other modifications of the locking system are possible, for example a locking element comprising a nut or an outer cap. The filling part 22 is then rotatably connected to an element of the locking system. It is also possible to modify the locking system in two parts described above, for example the first blocking element 30 may have a non-threaded section in its coaxial bore with a diameter larger than that of the filler, so that the first element Lock 30 does not touch the surface 26 of the filler. The filling piece may extend, in this case, above the pins 18, 19.
The receiving part can be designed to allow the screw to be introduced from the bottom.
The rod can be totally or partially tubular. The core can be omitted. The rod can be rigid or totally or partially flexible.
Other modifications are possible. Instead of a bone screw, an anchoring element similar to a hook or nail can be provided. The elements of the different embodiments described can be combined. The two-part locking system can also be used, for example, with a monoaxial screw.
1. Bone anchoring device comprising
an anchoring element (2, 2 ') that includes a rod (3) to be fixed in a bone or a vertebra and a receiving part (5, 5') connected to the rod;
a rod (20, 20 ') for connecting at least two anchoring elements;
wherein the receiving part (5, 5 ') comprises a receptacle (5a, 11) for housing said rod;
a blocking element (50, 29) that cooperates with the receiving part to secure the rod in the
receptacle, where the blocking element comprises a first blocking element (30) and a second
blocking element (31);
a filling piece (60, 22) arranged between the blocking element (50, 29) and the rod (20, 20 ') to exert pressure on the rod in order to block it in the receptacle, the filling part comprising a contact surface (61, 25) with the rod that contacts a part of said rod, the shape of the rod contact surface adapting to the shape of the rod segment
characterized in that said rod has at least part of it a tubular shape (31) and the filling piece (22) is connected either with the first blocking element or with the second blocking element.
Bone anchoring device according to claim 1, characterized in that the filling part (60, 22) is rotatably connected with the locking element (50, 29).
Bone anchoring device according to claim 2, characterized in that the rotating connection is made by means of a pin (63, 35) provided in the filling piece (60) or in the blocking element (29, 31), pin that engages in a hole (51, 27) provided in the blocking element (29, 31) or in the filling piece (60) respectively.
Bone anchoring device according to one of claims 1 to 3, characterized in that the filling piece (60, 22) can slide into the receiving part (5, 5 ').
Bone anchoring device according to one of claims 1 to 4, characterized in that the part of the rod that is in contact with the filling piece is tubular.
Bone anchoring device according to one of claims 1 to 5, characterized in that the receiving part (5) is monoaxially connected to the rod (3).
Bone anchoring device according to one of claims 1 to 5, characterized in that the rod (3) comprises a head (4) rotatably connected to the receiving part (5).
Bone anchoring device according to claim 7, characterized in that a pressure element (15) is provided between the rod and the head (4) to exert pressure on the head in order to fix this on the receiving part (5).
Bone anchoring device according to one of claims 1 to 8, characterized in that the rod is at least partially flexible under the action of forces due to the movement of the connected bone parts.
Bone anchoring device according to one of claims 1 to 9, characterized in that the rod has a core (41).
Bone anchoring device according to one of claims 1 to 10, characterized in that the rod is a tube made of metal or of a metal alloy.
ES06017651.8T 2006-08-24 2006-08-24 Bone anchoring device Active ES2453196T3 (en)
ES2453196T3 true ES2453196T3 (en) 2014-04-04
ES06017651.8T Active ES2453196T3 (en) 2006-08-24 2006-08-24 Bone anchoring device
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