|Publication number||US20070260246 A1|
|Application number||US 11/789,454|
|Publication date||Nov 8, 2007|
|Filing date||Apr 23, 2007|
|Priority date||Nov 27, 2001|
|Also published as||DE10157814A1, DE10157814B4, DE50211511D1, EP1316294A2, EP1316294A3, EP1316294B1, US7223268, US20030100904|
|Publication number||11789454, 789454, US 2007/0260246 A1, US 2007/260246 A1, US 20070260246 A1, US 20070260246A1, US 2007260246 A1, US 2007260246A1, US-A1-20070260246, US-A1-2007260246, US2007/0260246A1, US2007/260246A1, US20070260246 A1, US20070260246A1, US2007260246 A1, US2007260246A1|
|Original Assignee||Biedermann Motech Gmbh|
|Export Citation||BiBTeX, EndNote, RefMan|
|Referenced by (12), Classifications (9)|
|External Links: USPTO, USPTO Assignment, Espacenet|
The invention relates to a locking device for use in spinal column or accident surgery for securing a rod-shaped element in a holding element connected to a shank. The invention further relates to an element with a shank and a holding element connected to it for connecting to a rod with a locking device of this kind.
From WO 95/01132 and U.S. Pat. No. 6,224,598 B1 a spinal column implant with a receiving part with a U-shaped recess for receiving a rod is known, respectively, wherein the open legs formed by the U-shaped recess have an inner thread. To fix the rod a locking element, which can be screwed in between the legs, with an outer thread, a central bore with inner thread and an inner screw which can be screwed into the locking element is provided. In the device known from WO 95/01132 a security sleeve encircling the legs from outside is used to avoid splaying of the legs.
It is the object of the invention to create a locking device of the kind initially described which guarantees improved security against loosening or detaching of the locking elements and at the same time is compactly built and easy to produce.
This object is achieved by the locking device characterised in claim 1 or by the element characterised in claim 5. Further developments of the invention are given in the subordinate claims.
The invention is suitable for both monoaxial and polyaxial bone screws, as it allows fixing of the rod or the rod and the head of the bone screw in the final state to cooperate in such a way that there is secure blocking against loosening or detaching of the locking mechanism.
Further features and advantages of the invention emerge from the description of embodiment examples using the figures.
The element according to the invention in the embodiment illustrated in
To lock the rod 100 in the recess 3 a sleeve-type or nut-type locking element 8, which can be screwed in between the legs 4, 5, is provided, with an outer thread 9 cooperating with the inner thread 7 of the legs and an inner thread 10. The locking element 8 has a first front end 11 and opposite this a second end 12. Radially running notches 13 are provided on the first front end 11 for bringing into engagement with a screwing in tool. One of the notches extends through the entire locking element 8 in the axial direction and thus forms a slit 14 in such a way that the locking element has a certain elasticity in the manner of a straining ring. The length of the locking element 8 in the axial direction is dimensioned in such a way that the locking element can be fully screwed in between the legs 4, 5.
Further provided is an inner screw or clamping or set screw 15, which can be screwed into the locking element and the outer thread 16 of which cooperates with the inner thread 10 of the locking element 8. The inner screw 15 has on one of its ends a recess 17 for bringing into engagement with a screw tool.
In the embodiment shown in
In operation the bone screw 100 is first screwed into the bone and then the rod 100 is placed in. The locking element 8 is then screwed in with the inner screw 15 already screwed in, but not yet touching the rod with its underside, whereby the rod is at first only prevented from tilting out, but is still displaceable. When the locking element 8 is screwed in no splaying of the legs 4, 5 arises, owing to the slit and therefore elastic construction, but, as shown in
In the embodiment shown in
Further provided is a pressure element 30, which is constructed in such a way that on its side facing the head 20 it has a spherical indentation 31, the radius of which is substantially identical to the radius of the section of the head 20 shaped like a segment of a sphere. The outer diameter of the pressure element is chosen in such a way that the pressure element can perform a sliding movement in the receiving part 21, in other words is displaceable towards the head 20. The pressure element further has a coaxial bore 32 for access to a recess 33 in the screw head 20 for bringing into engagement with a screwing in tool.
Construction of the locking element 8 and the inner thread 15 is as in the first embodiment.
In operation the screw element is screwed into the bone after being placed into the receiving part 21. The pressure element 30 and the rod 100 are then inserted in turn. At this stage the screw head 20 is still swivellable. By screwing in the locking element 8 and the inner thread 15 in the same way as in the first embodiment the screw element and the receiving part 21 are fixed to one another and therefore the rod 100 is also fixed.
The third embodiment illustrated in
The pressure element 40 of this embodiment is substantially constructed as cylindrical with an outer diameter which is chosen in such a way that the pressure element 40 can slide in the second bore 23 of the receiving part 21′. On one of its ends a recess 41, shaped like a segment of a sphere and widening towards the end is provided, the sphere radius of which is chosen in such a way that, in a state inserted into the receiving part, it partially encircles the head 20 of the screw element. A substantial difference from the pressure element 30 of the second embodiment is that the pressure element 40 of the third embodiment is lengthened in the direction of the open end 28 of the legs. For this purpose it has on its end opposite the recess 42 shaped like a segment of a sphere a U-shaped recess 42, wherein the dimensions of the U-shaped recesses of the pressure element are such that the rod 100 can be placed in the channel formed thereby. The depth of the U-shaped recess 42, seen in the direction of the cylindrical axis of the receiving part 21′ is larger than the diameter of the rod 100 to be received, so that the pressure element 40 projects upwards above the placed in rod 100 with lateral legs 43. The pressure element 40 further has a central bore 44 extending therethrough. The diameter of the central bore 44 is just large enough for a screw tool for bringing into engagement with the recess 33 provided in the head 20 to be guided through.
Construction of the locking element 8 and the inner thread 15 is as in the first and second embodiments.
In operation the third embodiment shown in
The embodiments shown in FIGS. 5 to 7 differ from the third embodiment shown in
In the embodiment shown in
In operation the legs 26, 27 experience a force component directed radially inwards owing to the negative flank angle when the locking element 8 is tightened, wherein the flanks 29 a and lob come to be on top of one another, so the legs are slightly pulled together. This gives rise to reliable blocking of the head 20 via the pressure element 40. When the inner screw is screwed in, the locking element 8 splays out owing to the force component which is then acting radially outwards and therefore acts against the force pulling the legs together. The rod is fixed and simultaneously blocking of the locking element 8 and legs against one another takes place.
The embodiment shown in
The embodiment shown in
A flank play is also provided in the thread forms shown in
In the embodiment shown in
In operation, when the locking element is screwed in, the projection 81 forms a stop which limits the force on the pressure element to a predetermined value.
Further embodiments of the invention emerge from the provision of the types of thread according to the embodiments according to FIGS. 5 to 6 and/or the locking element according to
Instead of the above-described embodiments, in which the receiving part is connected to a bone screw, the receiving part can also be connected to a hook, as used in spinal column surgery for hooking in behind bone projections of the spinal column.
In a further modification of the polyaxial embodiments, instead of the thread shank 1 or the hook, a bar or a rod-shaped element is provided, which has on both ends a head shaped like a segment of a sphere, which is connected to a receiving part of the kind described. In this way an element of this kind can be used as a connecting element between two rods 100.
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US7875065||Apr 1, 2008||Jan 25, 2011||Jackson Roger P||Polyaxial bone screw with multi-part shank retainer and pressure insert|
|US7901435||May 28, 2004||Mar 8, 2011||Depuy Spine, Inc.||Anchoring systems and methods for correcting spinal deformities|
|US8088152||Aug 28, 2008||Jan 3, 2012||Aesculap Ag||Orthopedic retaining system|
|US8167914||Jul 16, 2008||May 1, 2012||Zimmer Spine, Inc.||Locking insert for spine stabilization and method of use|
|US8308773||Dec 14, 2006||Nov 13, 2012||Medyssey Co., Ltd.||Pedicle screw|
|US8465528||Aug 28, 2008||Jun 18, 2013||Aesculap Ag||Surgical retaining screw|
|US8556938||Oct 5, 2010||Oct 15, 2013||Roger P. Jackson||Polyaxial bone anchor with non-pivotable retainer and pop-on shank, some with friction fit|
|US9011450||Aug 8, 2012||Apr 21, 2015||DePuy Synthes Products, LLC||Surgical instrument|
|US20130066380 *||Mar 14, 2013||Aesculap Implant Systems, Llc||Two step locking screw assembly|
|US20130218207 *||Feb 16, 2012||Aug 22, 2013||Warsaw Orthopedic, Inc||Dynamic multi-axial anchor|
|WO2013053885A3 *||Oct 12, 2012||Jun 6, 2013||Medos International Sarl||Bone anchor assemblies|
|WO2014052117A1 *||Sep 18, 2013||Apr 3, 2014||Medos International Sarl||Bone anchor assemblies|
|International Classification||A61B17/56, A61B17/70, A61B17/58|
|Cooperative Classification||A61B17/7035, A61B17/7049, A61B17/7032|
|European Classification||A61B17/70B5, A61B17/70B2|