Osteosynthetic implants and methods of use and manufacture
View Patent ↗Bone fracture fixation devices, systems and methods of use and manufacture are provided. One such bone fixation device includes an elongate element having a responsive zone. The element is adapted to be coupled to the bone so that the responsive zone is positioned adjacent a fracture or fusion site in the bone. The responsive zone is adapted to apply a desired pressure to the bone when coupled thereto. In some embodiments, the responsive zone comprises a shape memory material, which may be nickel titanium or Nitinol, to apply compressive pressure across the fracture or fusion site for longer periods of time than standard bone screws.
1. A method of manufacturing a shape memory alloy medical device element, the method comprising:
performing a first heat treatment operation on a shape memory alloy including a first heating cycle of the shape memory alloy to between about 500 degrees Celsius and about 550 degrees Celsius for between about 5 minutes and about 1.5 hours;
wherein the first heat treatment operation further comprises a second heating cycle performed before the first heating cycle, the second heating cycle comprising heating the shape memory alloy to above about 600 degrees Celsius for between about 5 minutes and about 1.5 hours;
after the first heat treatment operation, machining the shape memory alloy into the shape memory alloy medical device element; and
after machining, performing a second heat treatment operation on the shape memory alloy medical device element.
2. The method of claim 1 , wherein the first heat treatment operation further comprises:
transforming the shape memory alloy from a first state to a second state;
wherein the first state is a hot-rolled state of the shape memory alloy.
3. The method of claim 2 , wherein the shape memory alloy in the second state comprises an austenite phase.
4. The method of claim 2 , wherein the shape memory alloy has a first hardness value in the first state and the shape memory alloy has a second hardness value in the second state, different from the first hardness value.
5. The method of claim 4 , wherein the first hardness value is between about 100 percent and about 500 percent of the second hardness value.
6. The method of claim 2 , wherein the second heat treatment operation further comprises:
transforming the shape memory alloy from the second state to a third state.
7. The method of claim 6 , wherein the shape memory alloy in the third state exhibits instability of a martensitic phase of the shape memory alloy at about 37 degrees Celsius.
8. The method of claim 6 , wherein the shape memory alloy has a first hardness value in the first state and the shape memory alloy has a third hardness value in the third state, different from the first hardness value.
9. The method of claim 8 , wherein the first hardness value and the third hardness value are different by less than about 10 HRC, as measured on the Rockwell C Hardness Scale.
10. The method of claim 9 , wherein the first hardness value and the third hardness value are different by less than about 3 HRC, as measured on the Rockwell C Hardness Scale.
11. The method of claim 6 , wherein the shape memory alloy has a first shape recovery value in the first state and the shape memory alloy has a second shape recovery value in the third state, different from the first shape recovery value.
12. The method of claim 11 , wherein the first shape recovery value is at least 95 percent of the second shape recovery value.
13. The method of claim 1 , wherein the first heating cycle of the shape memory alloy is performed below a melting temperature for the shape memory alloy.
14. The method of claim 1 , wherein the first heating cycle further comprises:
heating the shape memory alloy to about 550 degrees for about 1.5 hours.
15. The method of claim 1 , wherein the second heat treatment operation further comprises:
heating the shape memory alloy medical device element to at least about 350 degrees Celsius for about 1.5 hours.
16. The method of claim 1 , wherein the second heat treatment operation further comprises:
heating the shape memory alloy medical device element to about 350 degrees Celsius for about 1.5 hours.
17. The method of claim 1 , wherein the second heat treatment operation further comprises:
heating the shape memory alloy medical device element to about 400 degrees Celsius for about 1.5 hours.
18. The method of claim 1 , wherein machining further comprises:
cutting the shape memory alloy on a lathe at a cutting speed of about 300 revolutions per minute.
19. The method of claim 1 , further comprising:
deforming the shape memory alloy medical device element.
20. The method of claim 19 , wherein the deforming further comprises:
creating a martensitic phase in at least part of the shape memory alloy medical device element.
21. The method of claim 19 , wherein the deforming is performed after the second heat treatment operation is performed.
22. The method of claim 19 , wherein the deforming is performed while the shape memory alloy medical device element is inside a patient.
23. The method of claim 22 , further comprising:
primarily fixing the shape memory alloy medical device element to a first bone element of the patient.
24. The method of claim 23 , wherein the primarily fixing is performed before the deforming is performed.
25. The method of claim 24 , further comprising:
secondarily fixing the shape memory alloy medical device element to a second bone element of the patient.
26. The method of claim 25 , wherein the secondarily fixing is performed after the primarily fixing is performed.
27. The method of claim 1 , further comprising:
removing an oxide layer from shape memory alloy.
28. The method of claim 27 , wherein removing is performed mechanically.
29. The method of claim 27 , wherein removing is performed after performing the first heat treatment operation on the shape memory alloy.