Abstract
In recent years, the most important problem in total hip replacement has been bone cement interface loosening. We have already reported on the importance of clear zone measurements with respect to loosening.
Here, we discuss the relation between the clear zone (radiolucent line) and sinking on the femoral component (distal migration) shown by radiological examination. A follow-up was done of 229 arthroplasties, there were performed without the use of a long-stem at our clinic from September 1975 to October 1980. Accordingly the minimum post-operative observation time was more than five years.
In 58 joints (25.3%), a clear zone was observed around less than two-thirds of the femoral component and there was no sinking. In 50 joints (21.8%), a clear zone was observed around less than two-thirds of it, and a sinking of less than 8mm appeared. In 48 joints (21.0%), a clear zone was observed around more than two-thirds of it and a sinking of more than 8mm. In all cases that there has been a clear zone in zones 3 and 5 at the femoral component and in almost all cases with a clear zone in zones 1, 2, 4 and 6, sinking has been noticed. The appearance of a clear zone preceded sinking in most cases and the clear zone was closely connected with sinking.
