Double shell implant for cementless anchorage of joint prostheses
AssigneeScyon Orthopaedics AG
InventorsSlobodan Tepic, Henrik Malchau
Life of this patent
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Abstract
The invention solves the problem of anchoring a prosthetic component into compliant, cancellous bone by a thin, preferably pure titanium, or a titanium-based alloy, perforated, hence hydraulically open, shell (1, 13), spaced apart from the second, non-perforated shell (2, 14). In most applications, dictated by the anatomical site of insertion, shells are approximately hemispherical in form, connected to each other at the equator. The solid shell may contain a further, articulating component of the joint, e.g. a polymer or a ceramic insert, or it may serve that function itself. One or both components of a joint prosthesis can be anchored according to the invention.
Claims19
A prosthetic component for cementless integration into bone comprising two, spaced apart, shells (1, 2;
- 13, 14), wherein a bone facing shell (1;
- 13) is perforated to allow for rapid bony ingrowth and wherein the perforated bone facing shell (1) and the other shell (2) are fitted into each other, wherein the spaced apart shells (1, 2) contact each other only at circumferential edges thereof while a continuous gap (5) left between the spaced apart shells (1, 2) freely extends in the area surrounded by the circumferential edges of the shells (1, 2;
- 13, 14) in any direction for bony ingrowth, wherein opposite pairs of circumferential surfaces and opposite pairs of radially extending surfaces at the respective circumferential edges of the two shells contact each other in each pair defining a constant width of the gap in any direction;
- wherein the thickness of the perforated bone facing shell is in the range from 0.7 to 1.5 mm;
- and wherein the ratio of the thickness of the perforated bone facing shell to the perforation diameter is between 0.5 and 2.
A joint prosthesis comprising two joint components, wherein at least one of the joint components is anchored with a prosthetic component comprising two, spaced apart, shells (1, 2;
- 13, 14), wherein a bone facing shell (1;
- 13) is perforated to allow for rapid bony ingrowth and wherein the perforated bone facing shell (1) and the other shell (2) are fitted into each other, wherein the spaced apart shells (1, 2) contact each other only at circumferential edges thereof while a continuous gap (5) left between the spaced apart shells (1, 2) freely extends in the area surrounded by the circumferential edges of the shells (1, 2;
- 13, 14) in any direction for bony ingrowth, wherein opposite pairs of circumferential surfaces and opposite pairs of radially extending surfaces at the respective circumferential edges of the two shells contact each other in each pair defining a constant width of the gap in any direction;
- wherein the thickness of the perforated bone facing shell is in the range from 0.7 to 1.5 mm;
- and wherein the ratio of the thickness of the perforated bone facing shell to the perforation diameter is between 0.5 and 2.
An acetabular cup for a total hip prosthesis, comprising two, spaced apart, shells (1, 2;
- 13, 14), wherein a bone facing shell (1;
- 13) is perforated to allow for rapid bony ingrowth and wherein the perforated bone facing shell (1) and the other shell (2) are fitted into each other, wherein the spaced apart shells (1, 2) contact each other only at circumferential edges thereof while a continuous gap (5) left between the spaced apart shells (1, 2) freely extends in the area surrounded by the circumferential edges of the shells (1, 2;
- 13, 14) in any direction for bony ingrowth, wherein opposite pairs of circumferential surfaces and opposite pairs of radially extending surfaces at the respective circumferential edges of the two shells contact each other in each pair defining a constant width of the gap in any direction;
- wherein the thickness of the perforated bone facing shell is in the range from 0.7 to 1.5 mm;
- and wherein the ratio of the thickness of the perforated bone facing shell to the perforation diameter is between 0.5 and 2.
A resurfacing prosthesis for a femoral head comprising two, spaced apart, shells (1, 2;
- 13, 14), wherein a bone facing shell (1;
- 13) is perforated to allow for rapid bony ingrowth and wherein the perforated bone facing shell (1) and the other shell (2) are fitted into each other, wherein the spaced apart shells (1, 2) contact each other only at circumferential edges thereof while a continuous gap (5) left between the spaced apart shells (1, 2) freely extends in the area surrounded by the circumferential edges of the shells (1, 2;
- 13, 14) in any direction for bony ingrowth, wherein opposite pairs of circumferential surfaces and opposite pairs of radially extending surfaces at the respective circumferential edges of the two shells contact each other in each pair defining a constant width of the gap in any direction;
- wherein the thickness of the perforated bone facing shell is in the range from 0.7 to 1.5 mm;
- and wherein the ratio of the thickness of the perforated bone facing shell to the perforation diameter is between 0.5 and 2.
Dependencies are inferred from the claim text.