Abstract
Moderately to highly crosslinked UHMWPEs have functioned for at least a decade with dramatic reduction in wear volumes in THA. This wear reduction has been associated with a markedly reduced incidence of radiographic osteolysis. However, CT studies have demonstrated that osteolysis is not completely eliminated.
There, however, are still questions which include: Is cost for further improvements warranted?; Is 10 years long enough to assure that no clinically relevant osteolysis occurs, especially in younger patients?; Do we have any data demonstrating improvement in revision scenarios?; With high levels of crosslinking (requiring more radiation) some fractures have been demonstrated at the region of the locking mechanism of the liner to shell. Will this prevalence increase? These materials are softer and can cause quicker crack propagation than conventional polyethylene.; Do better locking mechanisms need to be developed to prevent fracture problems that have been demonstrated in the present generation cementless designs?; Do we need more information as to the optimal counterface choice (cobalt chrome, ceramic, oxinium)?; Can hip results be extrapolated to the knee where fatigue failure is a major problem both on the bearing surface and with the locking mechanism?; Is the oxidation we are beginning to see on the surface of retrieved liners (thought to be related to lipids from the synovium and cyclical loading) the tip of the iceberg?
I too am encouraged by the mid-term results of crosslinked polyethylene. Our own data supports it. However, we must keep in mind the questions outlined.
