M. Wrona et al., THE CORRELATION BETWEEN FUSION DEFECTS AND DAMAGE IN TIBIAL POLYETHYLENE BEARINGS, Clinical orthopaedics and related research, (299), 1994, pp. 92-103
Recent reports of fatigue failures of polyethylene tibial and patellar
components have led to investigation of the role of design and materi
al properties in these failures. Earlier investigations, concluding th
at high contact stress designs suffered greater damage in service, cou
ld not account for some of the fatigue failures. The current study hyp
othesizes that this failure is related to variations in the material p
roperties of the polyethylene due to incomplete consolidation of the p
owder during manufacture, resulting in fusion defects. Retrieved polye
thylene components and samples of polyethylene stock were examined to
gain insight into the relationship between fusion defects, component f
ailure, material forming processes, and powder grade. Statistically si
gnificant correlations (p < 0.05) were observed between the extent of
defects and cracking, delamination, total wear damage, and duration in
vivo. These correlations indicate that components manufactured from m
aterial with fusion defects may be less resistant to fatigue than comp
onents formed of fully consolidated material.