[Mechanical bending strength of explanted ex vivo bone cements compared with in vitro samples].
BACKGROUND
The mechanical properties of acrylic bone cements are an important factor in determining an efficient load transmission between prosthesis and bone to guarantee the long-term stability in cemented hip arthroplasty.


METHODS
Palacos and Refobacin Palacos specimens from 21 aseptically loosened femoral compoments of cemented hip arthroplasties manufactured by the first to third generation cementing technique have been mechanically tested in a standardised four-point bending test (ISO 5833). In vitro manufactured Palacos and Refobacin Palacos specimens served as a control group. The fatigue fracture surfaces were morphologically analysed with light microscopy.


RESULTS
Under in vitro conditions manufactured specimens had higher values of bending strength, with the exception of blood contaminated ones, compared to ex vivo specimens. Ex vivo specimens of the second and third generation cementing technique had higher values than specimens of the first generation.


CONCLUSIONS
Acrylic bone cements are subjected to a multifactorial material fatigue in vivo. Here, the art and quality of cementing technique is of eminent importance in determining the long-term stability of cemented hip arthroplasty.
Gravius
S
S
Klinik und Poliklinik für Orthopädie und Unfallchirurgie, Rheinische Friedrich-Wilhelms-Universität Bonn. sascha.gravius@web.de
Wirtz
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DC
Marx
R
R
Maus
U
U
Andereya
S
S
Müller-Rath
R
R
Mumme
T
T
D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000379:methods; D001696:Biomechanical Phenomena; D001843:Bone Cements; D046169:Dermoscopy; D005260:Female; D005839:Gentamicins; D006622:Hip Prosthesis; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D008768:Methylmethacrylates; D008875:Middle Aged; D019904:Polymethyl Methacrylate; D011474:Prosthesis Design; D011475:Prosthesis Failure; D013314:Stress, Mechanical; D013718:Tensile Strength; D016474:Weight-Bearing / Q000502:physiology*
D001843:Bone Cements; D005839:Gentamicins; D008768:Methylmethacrylates; C030159:gentamicin-polymethylmethacrylate bead; D019904:Polymethyl Methacrylate