Polymethylmethacrylate bone cements and methods for preparing such bone cements

• US 4,554,686 A
• Filed: 02/29/1984
• Issued: 11/26/1985
• Est. Priority Date: 02/29/1984
• Status: Expired due to Fees

• Current Assignee: University of Utah Research Foundation (State of Utah)
• Original Assignee: Optical Research Associates (Synopsys Incorporated)
• Inventors: Baker, Charles D.
• Primary Examiner(s): Apley, Richard J.
• Assistant Examiner(s): Cannon, A.
• Application Number:
  US06/584,605
• Time in Patent Office: 636 Days
• Field of Search: 3/1.91, 3/1.911, 3/1.912, 3/1.913, 427/398.1, 128/92 R, 523/117, 523/116, 523/115, 523/114, 523/113, 523/307, 528/481
• US Class Current: 606/92
• CPC Class Codes: A61L 24/06 obtained by reactions only involving carbon-to-carbon unsaturated bonds A61L24/043, A61L24/046 take precedence
• CPC Class Codes: A61L 2430/02 for reconstruction of bones; weight-bearing implants
• CPC Class Codes: C08L 33/12 Homopolymers or copolymers of methyl methacrylate

Abstract

The present invention is directed to polymethylmethacrylate bone cement that is premixed and frozen so as to arrest the polymerization reaction at a suitable point. The frozen bone cement is treated by electromagnetic radiation to insure sterility. In use, the bone cement is warmed until it reaches a temperature and consistency suitable for use. The bone cement may be prepackaged in a syringe, or may be molded for use in connection with a particular prosthesis, or may be packaged unitarily with a prosthesis.

Claims

1. A method for preparing polymethylmethacrylate bone cement for use in attaching a surgical prosthesis to prepared bone tissue, the method comprising the steps of:

mixing a bone cement composition including methylmethacrylate with a composition capable of initiating a polymerization of the methylmethacrylate;

blending the bone cement composition until a desired degree of partial polymerization has occurred;

placing substantially free flowing partially polymerized bone cement into syringe means;

freezing the partially polymerized bone cement in order to substantially arrest polymerization of the methylmethacrylate in the bone cement composition;

irradiating the frozen bone cement with suitable electromagnetic radiation capable of sterilizing the frozen bone cement without inducing substantial amounts of polymerization of the methylmethacrylate in the frozen bone cement; and

storing the sterilized, frozen bone cement at a temperature below about -70°

C. until use of the bone cement.

2. A method for preparing polymethylmethacrylate bone cement as defined in claim 1, wherein the freezing step is accomplished by placing the partially polymerized bone cement into freezing means capable of effecting rapid freezing of the bone cement.

3. A method for preparing polymethylmethacrylate bone cement as defined in claim 2, wherein said rapid freezing of the bone cement is effected in less than about 15 seconds.

4. A method for preparing polymethylmethacrylate bone cement as defined in claim 1, wherein the freezing step is accomplished by submerging the partially polymerized bone cement in liquid nitrogen.

8. A method for preparing polymethylmethacrylate bone cement as defined in claim 1, wherein the electromagnetic radiation is gamma radiation.

9. A method for preparing polymethylmethacrylate bone cement as defined in claim 8, wherein the gamma radiation is from a cobalt-60 source.

10. A method for preparing polymethylmethacrylate bone cement as defined in claim 8, wherein the frozen bone cement is maintained at a temperature below about -50°

C. during irradiation by gamma radiation.

11. A method for preparing polymethylmethacrylate bone cement as defined in claim 1, wherein the electromagnetic radiation is an electron beam.

12. A method for preparing polymethylmethacrylate bone cement as defined in claim 2, further comprising the step of placing the frozen bone cement into temperature maintenance means adapted to maintain the bone cement at a temperature wherein no substantial amount of polymerization occurs.

5. A method for preparing polymethylmethacrylate bone cement for use in attaching a surgical prosthesis to prepared bone tissue, the method comprising the steps of:

mixing a bone cement composition including methylmethacrylate with a composition capable of initiating a polymerization of the methylmethacrylate;

blending the bone cement composition until a desired degree of partial polymerization has occurred;

forming the partially polymerized bone cement into a suitable shape for use with a particular surgical prosthesis;

freezing the partially polymerized bone cement in order to substantially arrest polymerization of the methylmethacrylate in the bone cement composition;

irradiating the frozen bone cement with suitable electromagnetic radiation capable of sterilizing the frozen bone cement without inducing substantial amounts of polymerization of the methylmethacrylate in the frozen bone cement; and

storing the sterilized, frozen bone cement at a temperature below about -70°

C. until use of the bone cement.

18. A method for preparing polymethylmethacrylate bone cement as defined in claim 5 wherein the freezing step is accomplished by placing the partially polymerized bone cement into freezing means capable of effecting rapid freezing of the bone cement.

19. A method for preparing polymethylmethacrylate bone cement as defined in claim 18, wherein said rapid freezing of the bone cement is effected in less than about 15 seconds.

20. A method for preparing polymethylmethacrylate bone cement as defined in claim 5, wherein the freezing step is accomplished by submerging the partially polymerized bone cement in liquid nitrogen.

21. A method for preparing polymethylmethacrylate bone cement as defined in claim 5, wherein the electromagnetic radiation is gamma radiation.

22. A method for preparing polymethylmethacrylate bone cement as defined in claim 21, wherein the gamma radiation is from a cobalt-60 source.

23. A method for preparing polymethylmethacrylate bone cement as defined in claim 21, wherein the frozen bone cement is maintained at a temperature below about -50°

C. during irradiation by gamma radiation.

24. A method for preparing polymethylmethacrylate bone cement as defined in claim 5, wherein the electromagnetic radiation is an electron beam.

25. A method for preparing polymethylmethacrylate bone cement as defined in claim 18, further comprising the step of placing the frozen bone cement into temperature maintenance means adapted to maintain the bone cement at a temperature wherein no substantial amount of polymerization occurs.

6. A method for preparing polymethylmethacrylate bone cement for use in attaching a surgical prosthesis to prepared bone tissue, the method comprising the steps of:

mixing a bone cement composition including methylmethacrylate with a composition capable of initiating a polymerization of the methylmethacrylate;

blending the bone cement composition until a desired degree of partial polymerization has occurred;

forming the partially polymerized bone cement onto a surgical prosthesis;

freezing the partially polymerized bone cement while formed on the surgical prosthesis in order to substantially arrest polymerization of the methylmethacrylate in the bone cement composition;

irradiating the frozen bone cement and prosthesis with suitable electromagnetic radiation capable of sterilizing the frozen bone cement and the prosthesis without inducing substantial amounts of polymerization of the methylmethacrylate in the frozen bone cement; and

storing the sterilized, frozen bone cement and prosthesis at a temperature below about -70°

C. until use of the bone cement.

26. A method for preparing polymethylmethacrylate bone cement as defined in claim 6 wherein the freezing step is accomplished by placing the partially polymerized bone cement into freezing means capable of effecting rapid freezing of the bone cement.

27. A method for preparing polymethylmethacrylate bone cement as defined in claim 26, wherein said rapid freezing of the bone cement is effected in less than about 15 seconds.

28. A method for preparing polymethylmethacrylate bone cement as defined in claim 6, wherein the freezing step is accomplished by submerging the partially polymerized bone cement in liquid nitrogen.

29. A method for preparing polymethylmethacrylate bone cement as defined in claim 6, wherein the electromagnetic radiation is gamma radiation.

30. A method for preparing polymethylmethacrylate bone cement as defined in claim 29, wherein the gamma radiation is from a cobalt-60 source.

31. A method for preparing polymethylmethacrylate bone cement as defined in claim 29, wherein the frozen bone cement is maintained at a temperature below about -50°

C. during irradiation by gamma radiation.

32. A method for preparing polymethylmethacrylate bone cement as defined in claim 6, wherein the electromagnetic radiation is an electron beam.

33. A method for preparing polymethylmethacrylate bone cement as defined in claim 26, further comprising the step of placing the frozen bone cement into temperature maintenance means adapted to maintain the bone cement at a temperature wherein no substantial amount of polymerization occurs.

7. A method for preparing polymethylmethacrylate bone cement for use in attaching a surgical prosthesis to prepared bone tissue, the method comprising the steps of:

mixing a bone cement composition including methylmethacrylate with a composition capable of initiating a polymerization of the methylmethacrylate;

blending the bone cement composition until a desired degree of partial polymerization has occurred;

freezing the partially polymerized bone cement in order to substantially arrest polymerization of the methylmethacrylate in the bone cement composition;

irradiating the frozen bone cement with suitable electromagnetic radiation capable of sterilizing the frozen bone cement without inducing substantial amounts of polymerization of the methylmethacrylate in the frozen bone cement; and

storing the sterilized, frozen bone cement at a temperature below about -70°

C. until use of the bone cement;

warming the frozen bone cement to a temperature suitable to permit it to be used to attach a surgical prosthesis to prepared bone tissue.

34. A method for preparing polymethylmethacrylate bone cement as defined in claim 7 wherein the freezing step is accomplished by placing the partially polymerized bone cement into freezing means capable of effecting rapid freezing of the bone cement.

35. A method for preparing polymethylmethacrylate bone cement as defined in claim 34, wherein said rapid freezing of the bone cement is effected in less than about 15 seconds.

36. A method for preparing polymethylmethacrylate bone cement as defined in claim 7, wherein the freezing step is accomplished by submerging the partially polymerized bone cement in liquid nitrogen.

37. A method for preparing polymethylmethacrylate bone cement as defined in claim 7, wherein the electromagnetic radiation is gamma radiation.

38. A method for preparing polymethylmethacrylate bone cement as defined in claim 37, wherein the gamma radiation is from a cobalt-60 source.

39. A method for preparing polymethylmethacrylate bone cement as defined in claim 37, wherein the frozen bone cement is maintained at a temperature below about -50°

C. during irradiation by gamma radiation.

40. A method for preparing polymethylmethacrylate bone cement as defined in claim 7, wherein the electromagnetic radiation is an electron beam.

41. A method for preparing polymethylmethacrylate bone cement as defined in claim 34, further comprising the step of placing the frozen bone cement into temperature maintenance means adapted to maintain the bone cement at a temperature wherein no substantial amount of polymerization occurs.

13. A sterile frozen bone cement composition including methylmethacrylate and suitable polymerization initiating agents wherein polymerization has been initiated but arrested at a desired degree of partial polymerization, said partially polymerized bone cement composition being placed into syringe means while in a substantially free-flowing condition and then frozen while in said syringe means, and wherein the frozen partially polymerized bone cement in the syringe is maintained at a temperature below about -70°

C. until use.

14. A sterile frozen bone cement composition including methylmethacrylate and suitable polymerization initiating agents wherein polymerization has been initiated but arrested at a desired degree of partial polymerization, said partially polymerized bone cement composition being formed into a suitable shape for use with a particular surgical prosthesis and then frozen, and wherein the partially polymerized bone cement is maintained at a temperature below about -70°

C. until use.

15. A sterile frozen bone cement composition including methylmethacrylate and suitable polymerization initiating agents wherein polymerization has been initiated but arrested at a desired degree of partial polymerization, said partially polymerized bone cement composition being formed on a surgical prosthesis and frozen while secured to said prosthesis, and wherein the partially polymerized bone cement is maintained at a temperature below about -70°

C. until use.

16. A bone prosthesis for use in the repair of damaged bone tissue comprising a suitable prothesis;

and preformed sterile frozen bone cement secured thereto in a manner such that the prothesis and bone cement may be unitarily placed into prepared bone tissue to effect repair thereof, said frozen bone cement being partially polymerized, but having polymerization thereof arrested at a desired degree of polymerization.

17. A bone prosthesis as defined in claim 16, wherein the prosthesis and associated bone cement are maintained at a temperature below about -70°

C. prior to use.