Combination of augment and replacement piece for filling a bone defect
Graft for a bone defect, in particular a tibial head graft for a knee-joint endoprosthesis. It comprises a sleeve-like inner body ( 2 ) for implantation at one end of a long bone ( 99 ). An outer face of the inner body ( 2 ) is designed as a bone contact face ( 20 ) for bearing on the surrounding bone margin ( 97 ). According to the invention, an outer shell piece ( 3 ) is provided which, as a bone replacement piece, is doubled onto the outside of the inner body ( 2 ) for filling a defect at the cortical bone margin ( 97 ) and is not dimensioned peripherally, such that, in the circumferential direction, it covers only a part of the outer circumference of the inner body ( 2 ). The doubled outer shell piece ( 3 ) forms a filler piece for a bone defect (bone window 96 ) at the bone end. Closure of the bone window ( 96 ) is achieved, and unwanted contact between the graft and surrounding soft-tissue parts is avoided. Moreover, the graft is thus also supported in the region of the bone window ( 96 ). Parts of the bone margin ( 97 ) that are still present can thus remain intact, allowing the greatest possible preservation of naturally present bone substance.
1 . An augment for a bone defect comprising:
an inner body, designed as a sleeve for implantation at one end of a long bone, wherein the inner body comprises:
a channel, which extends from the top downward through the sleeve and serves to receive a prosthesis stem, and
a wall surrounding the channel, wherein an outer face of the wall is designed as a bone contact surface for bearing on a bone edge surrounding the inner body,
said bone contact surface comprising:
an outer shell piece bone replacement piece for filling a defect on the cortical bone edge, which is outside of the inner body and not dimensioned circumferentially, such that in the circumferential direction said outer shell covers only a part of the outer circumference of the inner body, wherein the outer shell piece has a lower region, a support saddle to rest on a cortical region of the long bone, wherein the support saddle is arranged higher than the lower end of the inner body.
2 . The augment as claimed in claim 1 , characterized in that the outer shell piece is designed as a likeness of a bone defect.
3 . The augment as claimed in claim 1 , wherein the outer shell piece has, on its outer surface, a contour similar to the bone edge, wherein the outer shell piece has a substantially constant thickness in the circumferential direction.
4 . The augment of claim 1 , wherein the inner body is free from the outer shell piece in the region of its lower end.
5 . The augment of claim 1 , wherein the outer surface in the region of the outer shell piece is different from the outer face of the wall of the inner body, and wherein the outer shell piece has a solid outer surface and the outer face of the wall of the inner body is porous.
6 . The augment of claim 1 , wherein the outer shell piece has anchoring grooves or holes to receive fastening wires.
7 . The augment of claim 1 , wherein the outer shell piece is stiffer than the inner body, has a lower porosity than the inner body, and is made of the same material as the inner body.
8 . The augment of claim 1 , wherein the outer shell piece is welded to the inner body or is manufactured integrally with the inner body by means of an additive manufacturing process.
9 . The augment of claim 1 , wherein the outer shell piece has a freely pre-selectable outline contour adapted to a bone defect of the bone edge.
10 . The augment of claim 1 , wherein transitions between outer shell piece and inner body are rounded.
11 . The augment of claim 1 , wherein a thickness of the outer shell piece varies, preferably over the height or along the circumference.
12 . The augment of claim 1 , wherein the outer shell piece merges at its upper end into a cover plate shared with the inner body, wherein the outer contour of the inner body is retained, or the outer shell piece has at its upper end a receptacle for a screw fastening, or the outer shell piece is hollow.
13 . The augment of claim 1 , wherein the outer shell comprises several pieces, which are each non-circumferential and in their entirety do not enclose the inner body, wherein at least one of the outer shell pieces is arranged at a different height from another one.
14 . The augment of claim 1 , wherein the inner body has a slot passing through its wall and the slot has a free space between two mutually overlapping tongues.
15 . An augment for a bone defect comprising:
an inner body, designed as a sleeve for implantation at one end of a long bone, wherein the inner body comprises, wherein the inner body has a slot passing through its wall and the slot has a free space between two mutually overlapping tongues:
a channel, which extends from the top downward through the sleeve and serves to receive a prosthesis stem, and
a wall surrounding the channel, wherein an outer face of the wall is designed as a bone contact surface for bearing on a bone edge surrounding the inner body,
said bone contact surface comprising:
an outer shell piece bone replacement piece for filling a defect on the cortical bone edge, which is outside of the inner body and not dimensioned circumferentially, such that in the circumferential direction said outer shell covers only a part of the outer circumference of the inner body.
16 . The augment as claimed in claim 15 , wherein the outer shell piece has, on its outer surface, a contour similar to the bone edge, wherein the outer shell piece has a substantially constant thickness in the circumferential direction.
17 . The augment of claim 15 , wherein the inner body is free from the outer shell piece in the region of its lower end.
18 . The augment of claim 15 , wherein the outer surface in the region of the outer shell piece is different from the outer face of the wall of the inner body, and wherein the outer shell piece has a solid outer surface and the outer face of the wall of the inner body is porous.