Since the use of the Charnley hip prothesis, the component loosening has been the most
common causes of failure.
Although the detailed mechanism of loosening is as yet unclear, mehanical factors including quality of fixation, stress transfer and biologic factors such as tissue necrosis, healing and response to particulate debris have been under close
scrutiny.
The 18 patients who have admitted for revision at Seoul Paik Hospital from Sep. 1992 to Apr. 1993 by late loosening (more than ten years after postoperatively) of acetabular cup after being performed Charnley Low-Friction arthroplasty were
studied
about
the radiographic analysis, correlation of the real and radiographic measurement of wear and microscopic examination of granuloma tissue.
@ES The results were as follows:
@EN 1. The mean at revision was 57 years old and the average time to revision was 13 years
2. Acetabular radiolucent line (more than 2mm) was found in all cases and 12 cases(67%) of them was involved all three zones and the most common site was a zone III(16 cases:89%). Femoral radiolucent line was found in 16 cases (89%), 11 cases of
them
was definite loosening (more than 2mm) and the most common site was a zone 7 (9 cases : 60%).
3. The average wear of polyethylene cup measured from radiographs by Charnley and Oupic(1973) was 2.98mm and average wear rate was 0.23mm/year, the real wear by Wrobleski(1985) was 3.47mm and average wear rate was 0.27mm/year.
4. There was a significant correlation between time & real wear and between radiological & real wear on measurement but no correlation between the patient's weight and real wear of the socket.
5. In all cases there was seen the granulomalike materials at revision and was found polyethylene debris in all of them under the light and polarized microscope. In the 14 cases the polyethylene cup and bone cement were well fixed and cement
particles
were either absent(12 cases) or only found in minimal amount(2 cases).
6. The late loosening after Charnley low-friction arthroplasty is probably thought to the deficient structure of the bone of the acetabulum, that is initiated the osteolysis which is developed by the biologic reaction of polyethylene wear debris.
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