초록 ▼

The invention relates to an implantable orthopaedic device comprising a load-bearing element, such as a bone plate, for fixing elements, such as bone screws, that can be oriented polyaxially. The load-bearing element is equipped with at least one opening for the passage of the fixing elements. A two

The invention relates to an implantable orthopaedic device comprising a load-bearing element, such as a bone plate, for fixing elements, such as bone screws, that can be oriented polyaxially. The load-bearing element is equipped with at least one opening for the passage of the fixing elements. A two part insert is provided in the opening, the insert having an external form that complements the internal form of the receiving opening and permits the polyaxial rotation of the insert in the opening. The insert is equipped with a central bore for receiving the body of the fixing element. The first insert element part has a central inner hollow chamber, into which the second insert element part can be introduced. The first insert element is flexible or has at least one slit, in such a way that when the two insert elements are displaced axially in relation to one another, the first insert element in the plate can be expanded at least partially in order to block the position and alignment of the fixing element in the device in a polyaxial manner.

대표청구항 ▼

The invention claimed is: 1. An implantable orthopedic device comprising a load-bearing plate, with at least one polyaxially-oriented fixation element, the load-bearing plate has at least one opening having a part-spherical inner surface for the passage of said at least one polyaxially-oriented fix

The invention claimed is: 1. An implantable orthopedic device comprising a load-bearing plate, with at least one polyaxially-oriented fixation element, the load-bearing plate has at least one opening having a part-spherical inner surface for the passage of said at least one polyaxially-oriented fixation element, and first expandable insert, which may be inserted into said opening, the first expandable insert having a part-spherical outer shape that is complementary to the inner part-spherical shape of the opening to allow a polyaxial rotation of the insert in the opening, the first expandable insert having a central through-bore extending along an axis for accepting a body of the fixation element and allowing the polyaxial rotation of the same and further comprising a second insert for holding the first insert in the opening the first expandable insert element having a central recess surrounding the through-bore thereof for receiving the second insert, the first expandable insert element is capable of being expanded, by relative displacement of the first and second insert elements, the first expandable insert having two slits extending partially through the first expandable insert from a first side and two slits extending partially therethrough from a second side of the first insert; the first and second sides of the first expandable insert element extending transverse to the direction of the axis and the implantable orthopedic device further comprising a means for holding the first and second inserts in the opening which includes a third ring-shaped insert that is inserted in a recess in the plate surrounding the at least one opening and extending part way through a thickness of the plate from a bone contacting side of the plate and into contact with the first expandable insert. 2. The device as claimed in claim 1, wherein the first expandable insert is positioned adjacent a side of the plate opposite the bone contacting side and has a stop shoulder around the central through-bore thereof for contacting a head of the fixation element. 3. The device as claimed in claim 2, wherein a through-bore of the second insert at least partially includes an inner threading for engaging an outer threading of the fixation element. 4. The device as claimed in claim 2, wherein the central recess in the first expandable insert tapers inwardly towards the head of the fixation element and the second insert has a tapering shape that is complementary to the taper of the central recess of the first insert. 5. The device as claimed in claim 3, wherein the second insert has a through bore and has on a side opposite the bone contacting surface of the plate, a shoulder around the central through-bore for engaging the head of the fixation element. 6. The device as claimed in claim 1, wherein the central recess in the first expandable element is tapered and widens in the direction of the bone contacting surface of the bone plate and second insert is designed with a tapered shape that is complementary to the recess in the first insert. 7. The device as claimed in claim 1 wherein the third ring-shaped insert element exhibits an inwardly-directed shoulder that can be brought into engagement with the second insert element. 8. The device as claimed in claim 1, wherein the means for holding the second insert in the at least one opening includes lug on an end of the first expandable insert adjacent the plate bone contacting surface. 9. A locking system for a polyaxial bone screw mounted in a bone plate comprising: a bone plate having an aperture with a part-spherical wall; a bone screw having a head and a threaded shank; an insert mounted in said aperture in said bone plate having an expandable first part with a part-spherical outer surface for engaging said part-spherical wall of said aperture, and a through-bore for receiving said bone screw along an axis, said insert having a second part slidably mounted within said first part and having a through-bore aligned with said through-bore of said first part, said first part having a tapered recess surrounding at least a part of said through-bore for engaging a tapered outer surface on said second part surrounding said through-bore thereof, one of said first or second parts engaging said thread on said bone screw shank and the other of said first or second parts engaging said bone screw head whereby relative axial movement of said first and second parts causes said first part to expand against said aperture wall and lock said polyaxial bone screw at a desire axial orientation with respect to said bone plate, the first part having two slits extending partially through the first part from a first side and two slits extending partially therethrough from a second side of the first part; the first and second sides of the first part extending transverse to the direction of the axis wherein the first and second inserts are held within the aperture by a third ring-shaped insert part that is insertable from a bone contacting side of the plate in a recess in the plate surrounding the aperture of the bone plate and extending part way through a thickness of the plate from the bone contacting side and into contact with the first insert part. 10. The locking system as claimed in claim 9, wherein the first insert part is positioned adjacent a side of the plate facing away from the bone and has a shoulder around the through-bore, which shoulder is provided as a stop for the head of the bone screw, the shoulder is arranged adjacent a central section of the first insert part connected to a tapered recessed surface surrounding said through-bore in said first part and the recess open towards the plate bone-contacting surface. 11. The locking system as claimed in claim 9, wherein the through-bore of the second insert part includes an inner thread for engaging an outer thread on the shank of the bone screw. 12. The locking element as claimed in claim 10, wherein the tapered recess of the first insert part tapers towards the head of the bone screw and the second insert part has an outer tapered surface that is complementary to the tapered recess. 13. The locking system as claimed in claim 11, wherein the second insert part, on a side opposite the plate bone-contacting surface has a shoulder around the through-bore which engages the head of the bone screw. 14. The locking system as claimed in claim 13, wherein the tapered recess of the first part widens in the direction of the plate bone contacting surface and the second insert element has a tapered shape that is complementary to the tapered recess. 15. The locking system as claimed in claim 9, wherein said third insert part has an inwardly-directed shoulder that can be brought into engagement with the second insert part. 16. The locking system as claimed in claim 9, wherein the first insert part includes a lug mounted on the end of the first insert part adjacent the plate bone-contacting surface.