Implantable orthopaedic device

p0001The invention relates to an implantable orthopedic device with a load-bearing element, comprising at least one polyaxially orientable fixing element, wherein at least one opening for the passage of polyaxially orientable fixing elements is provided in the load-bearing element and an insert insertable into said opening in a receptacle Said insert having an outer shape complementary to the inner shape of the receptacle allowing polyaxial rotation of the insert in the receptacle, the insert having a central bore therethrough for receiving the body of the fixation element, and wherein said implantable orthopedic device comprises means for holding, Of the insert in the receptacle.

p0002Such a device is, for example, shown in FIG <patcit id="pcit0001" dnum="US5954722A"><text>US 5,954,722</text></patcit> (Basis for the preamble of claim 1). At least one opening is provided in the plate which defines a receptacle into which a one-part insert, which is provided with a continuous slot, can be inserted, which has an internal thread into which a thread of the fixing element can engage. The opening of the plate is hollow-spherical, so that it forms a receptacle for the insert having a spherical outer surface. As a result, the insert can be oriented polyaxially with a fixing element screwed into the latter. When the fixation element is screwed into the insert, this expands the insert which now fixes the fixation element in its position in the receptacle.

p0003The <patcit id="pcit0002" dnum="US5607426A"><text>US 5,607,426</text></patcit> Shows another solution for the polyaxial fixing of a fixation element. At least one opening is also provided in the plate, which defines a receptacle into which a two-part insert can be inserted, the outer part of which has an external thread which can engage in an internal thread of the plate which is provided on the bone. The plate has a conical tapering of the opening on its side facing the bone. The complementarily shaped inner part of the insert is supported against this conical tapering. The inner part of the insert is slotted several times, hollow and intended to receive a spherical head of the fixation element. This is polyaxial orientable. When the outer part of the insert is screwed in, the latter presses on the inner part of the insert, As a result of its displacement in the direction perpendicular to the plate plane by the conical taper, reduces said cavity and thereby fixes the spherical head of the fixing element into its position. It is clear that the polyaxial fixation of the spherical head of the fixation element must take place beforehand and can be implemented by means of the use of a tool in a groove provided in this head.

p0004Starting from this state of the art, the invention is based on the object of improving a device of the type mentioned at the outset in such a way that it is easier, faster and safer to handle the surgeon.

p0005This object is achieved according to the invention by the fact that the insert consists of two insert elements with said through bore, that the first insert element has said external shape which allows the polyaxial rotation thereof in the receptacle, that the first insert element has a central internal cavity Wherein the first insert element has at least one slot in such a way that, upon an axial displacement of the two insert elements relative to one another, the first insert element is at least partially expandable in the plate in order to block the position and orientation of the fixing element in the device in a polyaxially adjustable manner .

p0006By providing a two-part insert element, a polyaxial locking can be ensured in a simpler manner, without this implying an increased effort on the part of the surgeon for the use of such configured bone plates.

p0007Further advantageous embodiments are characterized in the subclaims.

p0008The invention will now be described, by way of example, with reference to the accompanying drawings, in which: FIG. Show it:<dl id="dl0001" compact="compact"><dt>FIG</dt><dd>A sectional side view of a first exemplary embodiment of the device,</dd><dt>FIG</dt><dd>3 a sectional view of the first insert element from FIG <figref idrefs="f0001">FIG</figref>,</dd><dt>FIG</dt><dd>3 a cross-sectional view of the second insert element from FIG <figref idrefs="f0001">FIG</figref>,</dd><dt>FIG</dt><dd>A sectional side view of a first modified form of the first exemplary embodiment of the device,</dd><dt>FIG</dt><dd>A cross-sectional side view of a second modified form of the first exemplary embodiment of the device,</dd><dt>FIG</dt><dd>A side view of the first exemplary embodiment, cut in a different plane of the first insert element, according to FIG <figref idrefs="f0001">FIG</figref>, and</dd><dt>FIG</dt><dd>2 a sectional side view of a second exemplary embodiment of the device.</dd></dl>

p0009The <figref idrefs="f0001">FIG</figref> 14 is a sectional side view of a first embodiment of the apparatus. The reference numeral 1 designates the plate, which is generally a plate 1 intended for implantation on a bone, which plate usually has a plurality of holes 2 provided transversely to its main plane. The main axis of the holes 2 is designated by the reference numeral 3, and the bone material is used in the region 4 when the device is used. Instead of the plate 1, it is also possible to speak generally of a load-bearing element since, in addition to plates, other load carriers, for example, in particular, rods for the use of the invention can also be provided.

p0010The holes 2 (not shown) can be designed in the shape of a hollow cylinder so as to form parallel outer walls to the main axis 3. The openings themselves can be rounded or have a conical shape opening outwards. However, these parallel outer walls can also be designed differently, for example, the opening is tapered or the opening tapered in conical shape, to name only two simple rotationally symmetrical possibilities. The presence of projections 7 or 8 is essential. This means that a receptacle 9 is provided between these projections 7 and 8, respectively, which is hollow-spherical. In this case, the diameter of this hollow-spherical receptacle 9 is greater than the cylindrical hole region resulting from the projections 7 or 8. This ensures that flange-like circumferential projections 7 or

p0011This spherical insert element 10, which can be designated as the first, can then freely rotate about its center of the ball, which lies in the axis 3, <figref idrefs="f0001">FIG</figref> Illustrated in the vertical direction of the first insert element 10. However, the first insert element 10 can not fall out of the receptacle 9.

p0012In this case, the first insert element 10 is partially slotted at four points at a distance of 90 degrees from the top and at the bottom, which is better described in the detail drawing of FIG <figref idrefs="f0002">FIG</figref> Can be seen. Identical features are provided with the same reference symbols in all the drawings. The following in connection with the<figref idrefs="f0001">FIG</figref> Described features of the first insert element 10 can also be found in the detail drawing of this from the <figref idrefs="f0002">FIG</figref> Can be seen. Two slots 6 are arranged from above, two slots 6 are introduced into the first insert element 10 from below.

p0013In the <figref idrefs="f0001">FIG</figref> The cutting plane lies in the two oppositely arranged open-to-open slots 6. The first insertion element 10 has along the axis 3 a through-going bore 11 for the passage of a fixing element 5, the bushing extending on the bone-free side into a fixation element head receptacle 12 and thus a shoulder 13 on which the fixation element head can be supported. The shoulder 13 stresses a plane which is perpendicular to the main axis 3 of the first insert element 10.

p0014On the bone-near side, the first insert element 10 has along the axis 3 via a likewise widened cavity 14 for receiving a second insert element 20.

p0015The cavity 14 of the first insert element 10, which is provided for receiving the second insert element 20, also widens itself in the direction of the bone seam 4 and forms a conical wall surface 16. Instead of an opening cone, another rotationally symmetrical shape can also be selected with respect to the axis 3 .

p0016A bend (or, alternatively, a continuous transition through a rounding) 17 is provided at the end of the conical wall surface 16 near the bone, with which the cavity 14 of the first insert element 10 merges into a closing cone with a wall surface 18. The wall surface 18 can also be viewed as part of a peripheral inwardly projecting nose. In this case, it is sufficient for the holding function if only partial regions of the circumference have said inwardly projecting nose 18.

p0017The second insert element 20 is essentially complementary to the cavity 14 of the first insert element 10, so that it can be accommodated with play in the cavity 14 of the first insert element 10. The<figref idrefs="f0002">FIG</figref> FIG. 5 is a sectional view of the second insert member of FIG <figref idrefs="f0001">FIG</figref>In which the section 21 of the second insert element 20, which is largest at its circumference, can be better seen, which comes to lie in the region of the transition 17 of the first insert element 10. The second insert element 20 is held in the first insert element 10 by the wall surface 18 of the first insert element 10.

p0018The second insert member 20 is not slit and preferably incompressible. It has a continuous, internally threaded bore 22 into which said fixing element 5 can be screwed.

p0019The operation of the device is as follows. The plate 1 placed on the bone region 4 is prepared in the holes 2, in which the polyaxial fixation is provided, with the inserted two insertion elements 10 and 20. The fixing element 5, for example a screw, is placed directly or via a guide which holds it so that the main axis 3 of the screw 5 coincides with the main axis of the two insert elements 10 and 20. A broad angular range can be selected by the spherical external shape of the first insert element 10. When screwed in, the screw 5 first engages with the internal thread 22, which is later anchored in the bone, into the internal thread 22 of the second insert element 20 and subsequently into the bone material 4. As a result, the screw head moves from the side remote from the bone to the plate 1 and the first insert element 10. However, the diameter of the bone screw 5 and the associated thread size can also be selected in such a way that the said first external thread 25 of the bone screw 5 passes through the first insert element 10 without touching the first insert element 10. According to a cylindrical transitional shaft region 27, the screw has a second external thread 28. The second external thread 28 is cylindrical and engages in the thread 22 of the second insert element 20. That said first external thread 25 of the bone screw 5 passes through the first insert element 10 without touching it. According to a cylindrical transitional shaft region 27, the screw has a second external thread 28. The second external thread 28 is cylindrical and engages in the thread 22 of the second insert element 20. That said first external thread 25 of the bone screw 5 passes through the first insert element 10 without touching it. According to a cylindrical transitional shaft region 27, the screw has a second external thread 28. The second external thread 28 is cylindrical and engages in the thread 22 of the second insert element 20.

p0020In addition to the directional guidance of the screw 5 in the second insert element 20, a further determination of the orientation and orientation takes place at the moment when the head of the fixing element 5 enters the cavity 12 since then the side walls of the first insert element 10, First insertion element 10, provided that the diameter of the shank and the threads 27 and 28 of the bone screw 5 are correspondingly large. Then comes the moment at which the fixing element 5 is screwed so far that the head rests on the shoulder 13. From this point in time, a further rotation of the fixing element 5 causes an axial movement of the second insertion element 20 along the axis 3 to the cavity 14. The conical surfaces 16 of the two insert elements move toward one another and the inner, non-flexible second insert element 20 spreads the flexible first insert element 10 so that the spherical outer surfaces at least partially press against the wall 9. Thus, by simply tightening the fixation element 5, it is possible to establish and confirm the preset polyaxial orientation.

p0021Advantageously, the plate 1 and the insert elements 10 and 20 are made of medical steel or titanium or another material used in medical technology. In particular, PEEK can be used as the material, which - in addition to other materials - also makes possible a further advantageous embodiment of the first insert element 10. This first insert element 10 can then be designed without slots, since it is flexible in itself due to the choice of the material. Such an insert element 10 is then preferably reinforced with carbon fibers. It is essential that the first insert element is elastically deformable, the type and number of slots and / or the material selection being only two examples of possible embodiments. The said deformability or flexibility must allow spreading of the first insert 10 in the radial direction with respect to the receptacle 9. In the illustrated exemplary embodiment, the receptacle 9 is a hollow sphere centered in the thickness centrally of the plate 1.

p0022The <figref idrefs="f0003">FIGS. 4 and 5</figref> Sectional side views of two modified forms of the first embodiment of the apparatus. The region of the first and second insert elements 10 and 20 is of the same configuration as in FIG<figref idrefs="f0001 f0002">1 to 3</figref> Illustrated embodiment. As mentioned above, it is essential that the insert be held in the receptacle 9, as indicated by the position shown in FIG<figref idrefs="f0001">FIG</figref> Circumferential projections 7 and 8, respectively. These are in the<figref idrefs="f0001">FIG</figref> The edges of the receptacle 9 which are close to the surfaces of the plate 1 and which have a smaller diameter than the depth of the receptacle 9 themselves by their hollow-spherical shape. This requires a force expenditure when the insert is inserted.

p0023The <figref idrefs="f0003">FIG</figref> Shows an embodiment in which the plate 1 has an annular recess 31 in the vicinity of the bone. The insert elements 10 and 20 are then inserted into the receptacle 9 first and are fixed in such a way that a third insert element 30 is subsequently inserted as a ring into the corresponding recess 31 in the plate 1. In this case, the fixation can be provided by pressing, screwing, welding or another method which is customary in the medical technology. This third insert element 30 then has a spherical inner surface, which continuously supplements the receptacle 9 of the plate 1, so that the first insert element can now be supported on the circumference of the tapered edge 8 'on the bone-near side before implantation. The implantation itself takes place in a manner analogous to the first exemplary embodiment, That is to say by interaction of the two first and second insert elements 10 'and 20' over the complementary surfaces 16 without the third insert element 30 performing an essential function here. It only takes up the forces acting in the half of the bony during spreading of the first insert element 10.

p0024For the description of the first insert element 10 'according to the second modification of the first exemplary embodiment, reference is made to the description of FIG<figref idrefs="f0001">FIG</figref> Respectively. The difference between the two first insert elements 10 and 10 'is that, according to this modification of the exemplary embodiment, the first insert element 10 does not have a region 17 which has a bend or a continuous transition through a rounding from a widening portion into a tapered portion Section. Rather, the conical wall surface 16 ends or, for example, transitions into a surface parallel to the main plane of the plate 1. On the other hand, the second insert element 20 'has a region of the largest diameter. As a result, the first insert element 10 'and the second insert element 20' can be freely inserted into the opening 2 of the plate 1 from the lower side. They are fixed in the receptacle 9 in that a third insertion element 30 'is provided, Which is inserted as a ring into a corresponding recess 31 in the plate 1. In this case, the fixation can be provided by pressing, screwing, welding or another method which is customary in the medical technology. This third insertion element 30 'then has a conical surface 18' tapering towards the bone 4, against which the second insertion element 20 'can be supported before the implantation. The implantation itself takes place in an analogous manner to the above-mentioned excitations of the first exemplary embodiment, ie, by the interaction of the two first and second insert elements 10 'and 20' over the complementary surfaces 16. Welding or another method which is customary in medical technology. This third insertion element 30 'then has a conical surface 18' tapering towards the bone 4, against which the second insertion element 20 'can be supported before the implantation. The implantation itself takes place in an analogous manner to the above-mentioned excitations of the first exemplary embodiment, ie, by the interaction of the two first and second insert elements 10 'and 20' over the complementary surfaces 16. Welding or another method which is customary in medical technology. This third insertion element 30 'then has a conical surface 18' tapering towards the bone 4, against which the second insertion element 20 'can be supported before the implantation. The implantation itself takes place in an analogous manner to the above-mentioned excitations of the first exemplary embodiment, ie, by the interaction of the two first and second insert elements 10 'and 20' over the complementary surfaces 16.

p0025Instead of these complementary surfaces 16, which are shown as conical surfaces in the drawings, other surface shapes which allow a force and / or frictional connection can also be predefined which can be braced against one another when a fixing element is advanced through the insertion elements 10 'and 20'.

p0026In this case, the two insert elements 10 and 20 or 10 'and 20' are respectively fixed against the spherical inner walls of the plate 1 by spreading the side regions 41 of the first insert elements 10, 10 ', which is achieved by axially fixing the underside of the fixation element head on the shoulder 13 And against the central region 42 of the first insert element 10, 10 '. This engagement produces the axial counter-movement of the second insert element 20 or 20 'in the direction of its longitudinal axis 3, which thereby spreads the wing regions 41, the inner surfaces 16 of which in a complementary engagement with the corresponding surfaces of the second insert element 20 or tapers corresponding to the central region 42 20 '.

p0027The <figref idrefs="f0004">FIG</figref> Shows a side view of the first exemplary embodiment, cut in a different plane of the first insert element 10 <figref idrefs="f0001">FIG</figref>, Whereby the section passes through the solid material of the first insert element 10 and thus no slots are recognizable. Thus, this FIG. Also corresponds to an exemplary embodiment with a first insert element, eg of PEEK, which is flexible in itself.

p0028As an alternative to the thread 22, the second insert element 20 can also be provided with a smooth inner bore, so that there is no direct contact between the screw 5 and the second insert element 20. The function of the axial movement of the second insertion element 20 can then be realized by the lower side 29 of the second insertion element 20, which is guided further in the vicinity of the bone, which presses against the first insertion element 10 when it is being placed on the support and spreads it.

p0029The <figref idrefs="f0004">FIG</figref> Finally, a sectional side view of a second embodiment of the device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the figures, identical features have been provided with the same reference symbols. Here, the shoulder 13 "is provided for supporting in the inner insert element which is pressed against the outer insert element by the head of the screw 5. In order to achieve this, an internal thread 22" is provided in the outer insert element. The configuration of the nose 18 "and of the conical engagement surfaces 16" can be designed analogously to the first exemplary embodiment.