Thermomechanical method for cement extraction in revision arthroplasty.
BACKGROUND
In joint revision surgery, bone cement extraction remains a major challenge which even today has not seen a satisfactory solution yet. We studied in an experimental setting the impact of heat sources on the mechanical properties and microstructure of bone cement and determined the glass transition temperature (TG) of bone cement. As a result, it would be possible to establish a thermomechanical method which makes use of the structural and material-specific property changes inherent in bone cement at elevated temperatures.


METHODS
Prepared samples of polymerized bone cement were thermoanalyzed with a Netzsch STA 409 C thermal analyzer. Samples weighing approx. 55 mg were heated to 390 °C at a rate of 5 K/min. Both simultaneous differential thermal analysis and thermogravimetry were employed. The thermomechanically induced changes in the microstructure of the material were analyzed with a computed tomography scanner specifically developed for materials testing (3D-μXCT).


RESULTS
The bone cement changed from a firm elastic state over entropy-plastic (air atmosphere 60-155 °C) to a plastic viscosity state (air atmosphere >155 °C). Between 290 and 390 °C, the molten mass disintegrated (decomposition temperature).


CONCLUSIONS
Our study was able to determine the glass transition temperature (TG) of bone cement which was about 60 and 65 °C under air and nitrogen, respectively. Heating the dry bone cement up to at least 65 °C would be more than halve the strength needed to detach it. Bone cement extraction would then be easy and swift.
Department of Orthopedic Surgery, Traumatology and Plastic Surgery, University Hospital of Leipzig, Liebigstrasse 20, 04103, Leipzig, Germany. mohamed.ghanem@medizin.uni-leipzig.de.
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M
Ghanem
Faculty of Chemistry and Mineralogy, Professorship of Multifunctional Construction Materials, University of Leipzig, Leipzig, Germany.
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A
Koenig
Faculty of Chemistry and Mineralogy, Professorship of Multifunctional Construction Materials, University of Leipzig, Leipzig, Germany.
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F
Dehn
Department of Orthopedic Surgery, Traumatology and Plastic Surgery, University Hospital of Leipzig, Liebigstrasse 20, 04103, Leipzig, Germany.
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CE
Heyde
Department of Orthopedic Surgery, Traumatology and Plastic Surgery, University Hospital of Leipzig, Liebigstrasse 20, 04103, Leipzig, Germany.
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Josten
D001178:Arthroplasty; D001843:Bone Cements / Q000737:chemistry*; D055598:Chemical Phenomena; D020878:Device Removal / Q000379:methods*; D006358:Hot Temperature; D008422:Materials Testing; D012086:Reoperation; D044366:Transition Temperature
D001843:Bone Cements
Bone cement extraction; Glass transition temperature; Thermomechanical method