RADIAL-CAPITELLAR IMPLANT

Abstract

The present invention relates to a radial head implant with a head, a shaft and a threaded anchor.

Claims

1. The radial head implant according to claim 15, wherein the head comprises an interlocking element for fastening the head.

2. The radial head implant according to claim 1, wherein the interlocking element comprises a latch, a securing element and/or a detent element for at least one rotation position.

3. The radial head implant according to claim 15, wherein the head is designed concavely on an upper side for articulation with the capitulum humeri.

4. The radial head implant according to claim 15, wherein the head comprises an opening at a bottom or lower side with at least two different dimensions in one extension direction.

5. The radial head implant according to claim 15, wherein the threaded anchor comprises a self-tapping thread and a central through-opening.

6. The radial head implant according to claim 15, wherein the threaded anchor comprises a body that tapers in distal direction.

7. The radial head implant according to claim 15, wherein the shaft has an upper shaft part and a lower shaft part, wherein the upper shaft part is designed to be fastened to a head and the lower shaft part is designed to be inserted into a radius.

8. The radial head implant according to claim 7, wherein the lower shaft part may be inserted into a central through-opening of a threaded anchor, in particular according to claim 5 and/or claim 6.

9. The radial head implant according to claim 7, wherein the lower shaft part comprises at least one groove.

10. The shaft according to claim 7, wherein the upper shaft part comprises a holding pin for cooperation or interaction with the head.

11. The radial head implant according to claim 7, wherein the upper shaft part, measured from a longitudinal axis of the lower shaft part, comprises an extension in a first direction which differs from an extension in a second direction.

12. The radial head implant according to claim 7, wherein the upper shaft part comprises a base surface which is defined or limited by a circular arc and a straight line.

13. The radial head implant according to claim 7, wherein the upper shaft part comprises at least one bore for transmitting a torque.

14. A radial head implant according to claim 15, comprising a washer to be inserted between shaft and bone.

15. A radial head implant with a head, a threaded and a shaft.

16. A sawing template with a plate and a tongue mounted parallel to the plate, the tongue having a convexity towards the plate.

17. (canceled)

18. A shaft-implanting tool for inserting the shaft with the threaded anchor into the medullary cavity of a radius.

19. (canceled)

20. A bone processing tool with a stalk and a rasping element arranged laterally.

21. A kit with a radial head implant according to claim 15 and comprising at least one of the following aids: a sawing template with a plate and a tongue mounted parallel to the plate, the tongue having a convexity towards the plate; a head-applying tool for receiving the head and for fastening the head on a shaft being inserted in a radius; a shaft-implanting tool for inserting the shaft with the threaded anchor into the medullary cavity of a radius; a ratchet for screwing the shaft together with the threaded anchor into the radius; and a bone processing tool with a stalk and a rasping element arranged laterally.

22. A method for inserting a radial head implant encompassing the steps: positioning and/or aligning a sawing template (17) according to claim 16 at a radial head, at a capitulum humeri and/or at its joint space and positioning and/or aligning the sawing template along a radial shaft; determining the size of at least one of the radial shaft and of the radial head; resecting the radial head along a side of the plate or guide of the sawing template, the side being distal to the radial head; extending the medullary cavity of the radius using a bone processing tool with a stalk and a rasping element arranged laterally; inserting a shaft with a threaded anchor into the medullary cavity of the radius using a shaft-implanting tool for inserting the shaft with the threaded anchor into the medullary cavity of a radius; screwing the shaft with threaded anchor into the radius using a ratchet for screwing the shaft together with the threaded anchor into the radius; placing the head on the shaft using a head-applying tool for receiving the head and for fastening the head on a shaft being inserted in a radius; and interlocking the interlocking element of the head using the head-applying tool.

Description

[0132] In the following, the present invention is described based on preferred embodiments thereof with reference to the accompanying drawings. However, the present invention is not to be limited to these embodiments. The following applies in the figures:

[0133] FIG. 1 shows the radial head implant according to the present invention;

[0134] FIG. 2 shows the head according to the present invention for a radial head implant;

[0135] FIG. 3 shows the head according to the present invention in three further views;

[0136] FIG. 4 shows the shaft according to the present invention;

[0137] FIG. 5 shows the threaded anchor according to the present invention;

[0138] FIG. 6 shows the threaded anchor in which a shaft is inserted;

[0139] FIG. 7 shows the sawing template according to the present invention and a size gauge;

[0140] FIG. 8 shows the sawing template being inserted into a joint space;

[0141] FIG. 9 shows the bone processing tool according to the present invention;

[0142] FIG. 10 shows the shaft-implanting tool according to the present invention and the shaft with applied threaded anchor;

[0143] FIG. 11 shows the ratchet according to the present invention and the shaft with threaded anchor being inserted into the bone;

[0144] FIG. 12 shows the head-applying tool according to the present invention;

[0145] FIG. 13 shows the radial head implant with its interlocking element in two different rotation positions;

[0146] FIG. 14 shows the interlocking element of the head;

[0147] FIG. 15 shows the radial head implant, which is inserted into a radius and the washer according to the present invention; and

[0148] FIG. 16 shows the radial head implant with the washer in a further illustration.

[0149] FIG. 1 shows a radial head implant 1 with a head 2, a shaft 3 and a threaded anchor 4. FIG. 1a and FIG. 1d show views from below or from above, respectively. In FIG. 1b and FIG. 1c side views are shown and FIG. 1e, FIG. 1f and FIG. 1g show perspective views. In the side view of FIG. 1b, an interlocking element 5 can also be seen as well as the optional reference “M” which herein indicates the size of the implant. In FIG. 1g, an optional washer 6 is also seen which is put onto the shaft 3. In FIG. 1c, FIG. 1e and FIG. 1f, one of two (could be more than two) optional grooves 7 in the shaft 3 can be seen, which cooperates for example with two noses 8 in a through-opening 9 (see FIG. 5f) of the threaded anchor 4 and which results in a linear guide allowing an axial shifting of the shaft 3 in the threaded anchor 4. The grooves 7 and the noses 8 also allow a transmission of torque from the shaft 3 to the threaded anchor 4, which may be useful when screwing the radial head implant 1 or its threaded anchor 4 into a radial bone.

[0150] Groove(s) 7 and nose(s) 8 may alternatively be interchanged such that the groove(s) 7 is/are not provided on the shaft 3 rather on the threaded anchor 4, and vice versa.

[0151] There may be provided other elements instead of the groove(s) 7 and the nose(s) 8 for establishing a form-fit and/or force-fit connection between shaft 3 and threaded anchor 4.

[0152] FIG. 2 shows the head 2 of the radial head implant 1 in a view from below (FIG. 2a), from the side (FIG. 2b) and from above (FIG. 2d).

[0153] In FIG. 2e and FIG. 2f there is illustrated a perspective view of the head 2 from obliquely below or obliquely above, respectively. FIG. 2c shows a cut through a longitudinal axis of the interlocking element 5.

[0154] In particular, FIG. 2a and FIG. 2e clearly show an opening 10 in the head 2.

[0155] A first portion of the opening 10 comprises a larger diameter, and a second portion comprises a smaller diameter or smaller width (e.g. less than the diameter of the first portion). The portion of the opening 10 with the larger diameter comprises here a circular limitation. A subsequent rectangle (which herein again extends into a smaller circle or semicircle) comprises a smaller diameter or a smaller width.

[0156] First portion and second portion may together optionally have the shape of a keyhole.

[0157] In FIG. 3a to FIG. 3c there is again shown the head 2 with the opening 10 and the opening for inserting the interlocking element 5.

[0158] FIG. 4 shows a plurality of illustrations of the shaft 3 with a lower shaft part 11 and an upper shaft part 12 and the optional groove 7. A holding pin 13 of the upper shaft part 12 shows herein a wider, upper portion, in relation to the bottom portion, with an optional circular surface or base area. The bottom portion of the holding pin 13 lies between the upper portion and the proximal surface of the upper shaft part 12. The bottom portion of the holding pin 13 comprises herein purely optionally an angular and not a round cross section.

[0159] Two openings 14 are introduced in the upper shaft part 12. These can be used to transmit a torque from a tool to the shaft 3, for example, to screw the shaft 3 with its threaded anchor 4 into the radius.

[0160] The cut through the upper shaft part 12 in a plane perpendicular to the longitudinal axis of the lower shaft part 11 results in the example of FIG. 4 in a form which is defined through a (part-)arc (alternatively, a non-circular, for instance an oval (part) arc, the ends of which are connected by a straight line. In other words, the section has the shape of a circular section. By the shape of the upper shaft part 12, thus flattened, inserting the shaft 3 into the radius is facilitated in particular with minimally invasive surgery. The shaft 3 may thus be advantageously inserted into the radius also in case of a narrow operative access.

[0161] Instead of the two openings 14, a plurality of openings 14 may be provided. Alternatively, an opening 14 and a stop or the like would be sufficient to ensure the desired form-fit and/or force-fit connection for the tool

[0162] In FIG. 5, the threaded anchor 4 is shown from above (FIG. 5d), from below (FIG. 5a) and from the side (FIGS. 5b and 5c). FIG. 5f shows a sectional view, and in FIG. 5e the threaded anchor 4 is shown in a perspective view obliquely from below. The outer shape of the threaded anchor 4 corresponds substantially to a truncated cone, on which a thread is applied.

[0163] The thread 15 of the threaded anchor 4 is self-tapping, in particular also in left-hand rotation, to facilitate the removal of the radial head implant.

[0164] The thread 15 optionally comprises interruptions 16 at various (here: purely exemplary three) positions of the circumference in order to remove the bone material released during the threading and/or to break the chip.

[0165] In FIG. 5, the through opening 9 of the threaded anchor 4 is also illustrated. The noses 8 optionally present in the through-opening 9 for engaging in the grooves 7 of the lower shaft part 11 are also seen here. The noses 8 allow an axial shifting of the shaft 3 relative to the threaded anchor 4. In addition, a torque may be transmitted from the shaft 3 to the threaded anchor 4 via the grooves 7 and the noses 8.

[0166] FIG. 6 shows illustrations of the shaft 3 with applied or attached threaded anchor 4 from above (FIG. 6d), from below (FIG. 6a), from the side (FIGS. 6b and 6c), in section through the longitudinal axis (FIG. 6e), with a detail illustration (FIG. 6f) and in a perspective illustration obliquely from above (FIG. 6g).

[0167] The threaded anchor 4 is, in FIG. 6b to FIG. 6f, optionally releasably and securely jammed or snapped on the shaft 3. For this purpose, the portions of the lower shaft part 11 shown in FIG. 6e and enlarged in FIG. 6f engage in the proximal portion of the threaded anchor 4 at the transition to the upper shaft part 12. Attaching the threaded anchor 4 on the shaft 3 in a releasable and secure (against loss) manner prevents when inserting the shaft 3, an undesired falling out of the threaded anchor 4 which could potentially prolong or extend an operation or could even cause the threaded anchor 4 to become non-sterile. This is prevented by the shown releasable securing element.

[0168] In FIG. 7, the sawing template 17 according to the present invention is shown from the side (FIG. 7a), distally (FIG. 7b) and in perspective view from obliquely above (FIG. 7c).

[0169] The sawing template 17 comprises a plate 18 and a tongue 20 mounted via a connecting element 19 parallel to the sawing template 17. In addition, in FIG. 7a and FIG. 7c, through-openings 21 are shown which extend or continue to the outside in a short hollow cylinder. The through openings 21 serve for inserting wires with which the sawing template 17 may be fixed to the humerus. In this, only one through-opening 21 is used when operating the left arm and only the other through-opening 21 is used when operating the right arm.

[0170] To avoid confusion between them, the through-openings 21 are optionally marked on the connecting element 19, for instance with R and L.

[0171] The plate 18 has towards the radial head a preferably circular arc-shaped limitation, so that the plate 18 can support itself with the largest possible surface on the radial head. The tongue 20 optionally comprises a convexity in the direction of the plate 18, which serves for lying better on the concave joint surface of the radial head.

[0172] The sawing template 17 is inserted before the implantation together with its tongue 20 into the joint space, wherein the circular arc-shaped lower limitation of the sawing template 17 lies or rests laterally on the radial head. Subsequently, it is evaluated whether the sawing template 17 fits the radial head sufficiently accurately or whether another sawing template 17 with a different size should be used. This may be assessed haptically or visually. In this context, the sawing template 17 is used for determining the size of the radial head. When the correct size has been found, then the corresponding sawing template 17 may be inserted into the joint space and placed on the radius and fixed with a wire, as shown in FIG. 8a to FIG. 8d. Thereafter, the distal surface of the plate 18 may be used to guide for instance an oscillating saw to resect the radial head.

[0173] In several embodiments (FIG. 7d to FIG. 7f), the sawing template 17 may be used in conjunction with a size gauge 43. In this, the size gauge 43, which is guided in the plate 18 of the sawing template 17, may be put on the radial head for example with the aid of a slide 44 of the size gauge 43. In this, an arm 45 or the size gauge 43 is deflected by contact with the lateral edge of the radial head, so that an indicator 41 connected to the arm 45 is deflected. The deflection of the indicator 41 may be read on a scale 42 applied on the size gauge 43. In this, a value of the scale 42 corresponds to a specific size of a radial head, so that corresponding implant sizes and tools matching thereto in terms of size can be selected on the basis of the scale value.

[0174] The size of the resected radial head may be checked with a template (not shown) which has circular recesses of different diameters.

[0175] After the resection, a bone processing tool 22 with a rasping element 23 may be introduced into the medullary cavity of the radius (see FIG. 9a and FIG. 9b). By pivoting a stalk 24 of the bone processing tool 22, the medullary cavity is expanded by rasping. For this purpose, the surface of the rasping element 23 comprises for example notches or teeth.

[0176] In one embodiment (see FIG. 9c) of the bone processing tool 22 with stalk 24, this comprises a pusher 39 which may be shifted along a leaf spring 38. The rasping element 23 is fastened at the leaf spring 38. By shifting the pusher 39, the rasping element 23 may be pushed through the stalk 24. The pusher 39 is optionally equipped with a securing element, herein optionally designed as snap-in tongue which prevents the pusher 39 from slipping off the rasping element 23 away from the stalk 24.

[0177] The stalk 24 of the bone processing tool 22 may be designed as a ratchet.

[0178] The rasping element 23 may be designed to be interchangeable or replaceable, so that e.g. rasping elements 23 having different sizes may be used with the bone processing tool 22.

[0179] In FIG. 9d and FIG. 9e there is shown how to use the bone processing tool 22. The bone processing tool 22 lies thereby flatly with its stalk 24 on the resection plane of the radius. The axis of rotation of the rasping element 23 is thereby perpendicular to the resection plane. By rotational movements of the bone processing tool 22, the conical rasping element 23 being sprung by the leaf spring 38 cuts into the medullary cavity of the radius.

[0180] FIG. 9f and FIG. 9g show detailed views of the bone processing tool 22. In this, it can be seen that there is optionally a securing element 46 integrated in the leaf spring 38 which securing element 46 engages in the rasping element 23 and moreover serves for operating the rasping element 23. The securing element 46 of the leaf spring 38 is in FIG. 9g optionally designed as a tongue which extends in a narrow web leading away from the remaining leaf spring 38 and widening itself to a circular shape at its free end. The tongue is inserted into the rasping element 23 for the use of the bone processing tool 22 and transmits torques of the stalk 24 to the rasping element 23. For this purpose, the rasping element 23 optionally comprises a depression 47 corresponding to the securing element 46, in particular of the tongue.

[0181] The rasping element 23 is preferably designed conically and cuts, into a desired, size-dependent depth, into the radius by rotational movements of the stalk 24 and by the contact pressure of leaf spring 38 and pusher 39.

[0182] In this, the rasping element 23 is preferably matched to the dimensions of the threaded anchor 4, as shown in FIG. 9h and FIG. 9i.

[0183] In several embodiments, the rasping element 23 may comprise two or more steps. The conical rasping element 23 creates space in the radius for the threaded anchor 4 and for the shaft 3 by the removal of bone material using the bone processing tool 22. In addition, the rasping element 23 cuts free the space in the radius up to the base of the thread of the threaded anchor 4 thus allowing screwing in the threaded anchor 4 (see the broken line in FIG. 9i).

[0184] After processing the bone using the bone processing tool 22, the bone is ready for the insertion of shaft 3 with the optionally captively-secured attached threaded anchor 4.

[0185] The insertion is performed using a shaft-implanting tool 25 which is shown in FIG. 10a to FIG. 10c. The shaft implantation tool 25 comprises an optional elastic element 26 which serves for fixing or fastening the holding pin 13 onto the bone processing tool 22. The bone processing tool 22 also comprises two or more pins 27 which may be inserted into the openings 14 of the upper shaft part 12 to securely and precisely insert the shaft 3 into the radius. The situation after the insertion of the shaft 3, wherein the shaft 3 is still fastened at the bone processing tool 22, is shown in FIG. 10a.

[0186] In FIG. 10d to FIG. 10f it can be seen that the upper shaft part 12 viewed from above (FIG. 10f) and viewed from below (FIG. 10d), is laterally optionally flattened, e.g. in the sense of a circular section. In addition, it can be seen in FIG. 10e that the upper shaft part 12 can be beveled in proximal direction on its flat side, which may additionally facilitate a minimally invasive tipping of the shaft 3 into the radius.

[0187] The inserted shaft 3 having a threaded anchor 4 is shown in FIG. 11a, the threaded anchor lies herein still on the upper shaft part 12 and is not yet screwed into the bone. A ratchet 28 may then be applied on the upper shaft part 12, as shown in FIG. 11c and FIG. 11d. By rotating the ratchet 28, a torque may be transmitted to the threaded anchor 4 via the shaft 3 rotating due to the ratchet 28 so that the threaded anchor 4 is may be screwed deeper into the radius. However, since the shaft 3 is axially freely movable in the threaded anchor 4 (by engagement or guidance between groove 7 and noses 8), the position of the shaft 3 does not necessarily have to change due to screwing in the threaded anchor 4.

[0188] In FIG. 11e and FIG. 11f, it is illustrated that the upper shaft part 12 is optionally designed to rest on or abut the resection surface (indicated by arrows in FIG. 11e and 11f) of the radius and thus to provide a desired axis of rotation of the lower shaft part 11 with threaded anchor 4 or to provide at least the inclination of the rotation axis.

[0189] FIG. 11e shows the shaft 3 with threaded anchor 4 in an initial position after insertion. FIG. 11f shows that the threaded anchor 4—due to the rotation of the shaft 3, is screwed distally—i.e. into the radius.

[0190] In FIG. 12, a head-applying tool 29 is shown with the head 2 is attached to the inserted shaft 3 and/or with which the head 2 may interlock with the shaft 3 after being attached thereto or thereon. For this purpose, the head-applying tool 29 engages at the interlocking element 5.

[0191] In the example shown in FIG. 12, the interlocking element 5 optionally has a hexagon socket in which the head-applying tool 29 engages. Other geometrical forms such as the hexagon socket are also encompassed by the present invention.

[0192] The head-applying tool 29 is moved such that the holding pin 13 is introduced into the opening 10 of the head 2 or the head 2 is pushed with its opening 10 on the holding pin 13, in particular in an axial direction of the holding pin 13.

[0193] Thereafter, the head 2 is further moved, in particular in a radial direction, until the holding pin 13 is present in the narrower portion of the opening 10, thus, the holding pin 13 cannot be axially removed or pulled from the head 2.

[0194] In this position, the holding pin 13 is interlocked with the head 2. This is done by rotating the interlocking element 5 from an open to a closed rotation position using the head-applying tool 29.

[0195] In the closed rotational position, e.g. a latch 30 prevents that the holding pin 13 slips back into the wider portion of the opening 10. Thus, the head 2 is fastened relative to the upper shaft part 12 and thus also relative to the shaft 3.

[0196] In FIG. 13, the two rotational positions of the interlocking elements 5 can be clearly seen, wherein the position of the threaded anchor 4 relative to the shaft 3 needs not to be observed.

[0197] FIG. 13a and FIG. 13b show the open rotational position, while FIG. 13c and FIG. 13d show the closed rotational position.

[0198] In FIG. 13d, there is shown in a section that the latch 30 is in the way of the holding pin 13 or it limits its freedom of movement. Hence, this results in a form-fit connection, which prevents the holding pin 13 from slipping from the narrower into the wider portion of the opening 10 (here from left to right). Due to said limitation, the holding pin 13 cannot be removed from the head 2 anymore. In the open rotation position, the latch 30 is rotated upwards and releases the wider portion of the opening 10 (FIG. 13a and FIG. 13b). This makes it possible to introduce the holding pin 13 into the head 2 through the wider portion of the opening 10 or to remove it therefrom.

[0199] FIG. 14 shows the interlocking element 5. It is clearly seen that the interlocking element 5 has an optional hexagon socket on which the head-applying tool 29 may be applied in order to transmit a torque to the interlocking element 5.

[0200] An optional detent element 31 of the interlocking element 5 may cooperate with a corresponding depression of the head, such that the interlocking element 5 may engage in an open and/or closed rotational position.

[0201] In addition, the interlocking element 5 comprises an optional securing element 36 which is latched in e.g. a groove of the head 2.

[0202] An optional slot 32 in the interlocking element 5 may provide the necessary elasticity for latching. In addition, the slot 32 may preferably be used to rotate the interlocking element 5 with a screwdriver.

[0203] FIG. 15 shows washers 6 and their use. If it is ascertained, after introducing the radial head implant 1, that the joint space is still too wide, as indicated in FIG. 15a, and FIG. 15b by a slot between radius and lower side of the head 2, then a washer 6 may introduced for correction in this slot between upper shaft part 12 and radius. The washers 6 may be provided in different thicknesses, for example, with a thickness of 1, 3 and 5 mm.

[0204] In FIG. 16a, a radial head implant 1 is shown which optionally comprises, on the lower shaft part 11, e.g. a circumferential groove 35 for pushing the washer 6 on the lower shaft part 11. The groove 35 may prevent the washer 6 from slipping axially.

[0205] In FIG. 16b, a washer 6 is illustrated in detail.

[0206] The washer 6 comprises a central hole 33, which optionally continues into a slot 34 which extends until the edge of the washer 6. In this, the slot 34 is preferably slightly narrower than a diameter of the lower shaft part 11 such that the washer 6 must be slightly (pre-)tensioned for being pushed onto the lower shaft part 11.

[0207] In order to improve the elasticity of the washer 6, as shown in FIG. 16b, material may be removed from the portion of the washer 6 which lies on the side of the hole 33 away from or opposite of the slot 34. Herein, there is shown an opening which adjoins or extends into the hole 33. When the lower shaft part 11 has reached the central hole 33 during insertion, the washer 6 relaxes. Thus, the washer 6 is prevented from slipping again off the lower shaft part 11 after the completed insertion. This may be supported by the interlocking, detention or clamping which may be seen in FIG. 16b.

LIST OF REFERENCE NUMERALS

[0208] 1 radial head implant [0209] 2 head [0210] 3 shaft [0211] 4 threaded anchor [0212] 5 interlocking element [0213] 6 washer [0214] 7 groove [0215] 8 nose [0216] 9 through-opening of the threaded anchor [0217] 10 head opening or opening of or in the head [0218] 11 lower shaft part [0219] 12 upper shaft part [0220] 13 holding pin [0221] 14 bores or openings in the upper shaft part [0222] 15 thread of the threaded anchor [0223] 16 thread interruptions or threadless or thread-free section [0224] 17 sawing template [0225] 18 sawing template plate [0226] 19 connecting element of the sawing template [0227] 20 sawing template tongue [0228] 21 through-opening of sawing template [0229] 22 bone processing tool [0230] 23 rasping element [0231] 24 stalk of the bone processing tool [0232] 25 shaft-implanting tool [0233] 26 elastic element of the shaft-implanting tool [0234] 27 pins of the bone processing tool [0235] 28 ratchet [0236] 29 head-applying tool [0237] 30 latch of the interlocking element [0238] 31 detent element of the interlocking element [0239] 32 interlocking element slot [0240] 33 washer hole [0241] 34 washer slot [0242] 35 closed groove of the lower shaft part [0243] 36 securing element of the interlocking element [0244] 37 securing element of the pusher of the bone processing tool [0245] 38 leaf spring of the bone processing tool [0246] 39 pusher of the bone processing tool [0247] 41 size gauge indicator [0248] 42 size gauge scale [0249] 43 size gauge [0250] 44 size gauge slide [0251] 45 size gauge arm [0252] 46 securing element of the rasping element of the bone processing tool [0253] 47 rasping element depression