Medical devices incorporating SIM alloy elements
DCFirst Claim
1. A method of forming an attachment to a bone, which comprises positioning in an aperture in the bone an element formed at least partially from a shape memory alloy which displays stress induced martensite behavior at body temperature, the element being so positioned that it is deformed by the walls of the aperture by the formation of stress-induced martensite, and thereby exerts a force outwardly on the walls of the aperture.
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Accused Products
Abstract
Medical devices which are currently proposed to use elements made from shape memory alloys may be improved by the use of stress-induced martensite alloy elements instead. The use of stress-induced martensite decreases the temperature sensitivity of the devices, thereby making them easier to install and/or remove.
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Citations
40 Claims
- 1. A method of forming an attachment to a bone, which comprises positioning in an aperture in the bone an element formed at least partially from a shape memory alloy which displays stress induced martensite behavior at body temperature, the element being so positioned that it is deformed by the walls of the aperture by the formation of stress-induced martensite, and thereby exerts a force outwardly on the walls of the aperture.
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5. A method for installing a bone attachment into a bone of a mammalian body such that the device is substantially at body temperature, the method comprising the steps of:
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(a) providing a bone attachment device at least partly formed from a pseudoelastic shape-memory alloy, wherein the shape-memory alloy can display reversible stress-induced martensite at about body temperature such that the shape-memory alloy has a stress-induced martensitic state and an austenitic state, the memory alloy element having (i) a deformed shape when the alloy is in its stressed-induced martensitic state and (ii) a different unstressed shape when the allow is in its austenitic state; (b) deforming the bone attachment device with a tool at a temperature greater than the As of the alloy for placing the alloy in its stress-induced martensitic state and the bone attachment device in its deformed shape; (c) inserting and positioning the bone attachment device into a channel in the bone at a temperature greater than the As of the alloy while the bone attachment remains in its deformed shape; and (d) while maintaining the temperature of the bone attachment device above the As of the alloy, releasing the bone attachment device from the tool so that at least a portion of the alloy transforms from its stress-induced martensitic state so that the bone attachment device transforms from its deformed shape toward its unstressed shape to fill the bone channel and exert a constant force, wherein substantially all of the transformation occurs from releasing the bone attachment device from the tool and not from any change in temperature of the bone attachment device or the tool. - View Dependent Claims (6, 7, 8)
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9. A method for installing an implant into a bone in a mammalian body comprising the steps of:
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(a) drilling a channel in the bone; (b) selecting a bone implant comprised of a pseudoelastic shape memory alloy, the alloy displaying reversible stress-induced martensite at about body temperature such that it has a stress-induced martensitic state and an austenitic state, the bone implant having (i) an insertable shape suitable for insertion into the channel when the alloy is in its stress-induced martensitic state and (ii) a second different shape when the alloy is in its austenitic state, the bone implant being in its second shape; and (c) inserting the bone implant into the channel and stressing the bone implant so that the alloy transforms toward its stress-induced martensitic state and the bone implant transforms to its insertable shape. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 39)
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- 17. A bone implant sized for insertion into a channel in a bone in a mammalian body, the bone implant being comprised of a pseudoelastic shape memory alloy, the alloy displaying reversible stress-induced martensite at about body temperature such that it has a stress-induced martensitic state and an austenitic state, the bone implant having (i) an insertable shape for insertion into the bone when the alloy is in its stress-induced martensitic state and (ii) a second, different, non-insertable shape when the alloy is in its austenitic state.
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20. A method for holding onto a bone in a mammalian body comprising the steps of:
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(a) drilling a hole into the bone; (b) selecting a bone-holding device comprised of a pseudoelastic shape memory alloy, the alloy displaying reversible stress-induced martensite at about body temperature such that it has a stress-induced martensitic state and an austenitic state, the device having (i) a deformed shape when the alloy is in its stress-induced martensitic state and (ii) a different unstressed shape when the alloy is in its austenitic state, the bone-holding device being in its unstressed shape; and (c) inserting the device into the hole and deforming the device to its deformed shape so that the alloy transforms toward its stress-induced martensitic state. - View Dependent Claims (21, 22, 23, 24, 25, 26, 40)
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27. A method for removing from a mammalian body a medical device comprising a memory alloy element at least partly formed from a pseudoelastic shape memory alloy, the alloy displaying reversible stress-induced martensite at about body temperature such that it has a stress-induced martensitic state and an austenitic state, the device having (i) a removable shape when the alloy is in its stress-induced martensitic state and (ii) a different non-removable shape when the alloy is in its austenitic state, the device being positioned in a mammalian body and being in its non-removable shape, the method comprising the steps of:
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(a) stressing the device so that the alloy transforms toward its stress-induced martensitic state and the device transforms to its removable shape, without changing the temperature of the device; and (b) withdrawing the transformed device from the mammalian body. - View Dependent Claims (28, 29, 30, 31, 32, 33, 34, 35, 36)
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37. An article formed at least partially from a shape memory alloy which displays stress-induced martensite behavior at human body temperature, the article adapted to be positioned in an aperture in a bone of a human body so that the article is deformed by the walls of the aperture by the formation of stress-induced martensite, and thereby exerts a force outwardly on the wall of the aperture.
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38. A bone plate for compressing two ends of a fractured mammalian bone together, the bone plate being formed at least partly from a pseudoelastic shape-memory alloy, the alloy displaying reversible stress-induced martensite at about body temperature such that it has a stress-induced martensitic state and an austenitic state, the bone plate being (i) elongated when the alloy is in its stress-induced martensitic state and (ii) shortened when the alloy is in its austenitic state;
the bone plate being provided with means for securing the bone plate to both ends of a fractured bone.
Specification