Review Question - QID 6436

The outer diameter of the liner needs to be several sizes smaller than the shell to allow adequate room for cement. Revision for instability in the setting of a well-fixed acetabular component can be accomplished by cementing a new liner into the existing shell and therefore avoiding potential damage to the pelvis during extraction of the shell. This is particularly important when there is significant osteolysis behind the shell that might make reconstruction difficult. Biomechanical studies of liners cemented into well-fixed shells have shown that, when done well, the interface can be stronger than most acetabular locking mechanisms. Failures have occurred when the liner or shell was too smooth to allow inter-digitation of the cement or when there was not room for an adequate cement mantle. A liner that is too large will not be captured by the shell (as in this patient) and can result in failure. Impingement of the femoral component on the liner or shell can also lead to early failure of the construct.