INCIDENCE OF LATE BEAD SHEDDING FROM UNCEMENTED POROUS-COATED CUPS - A RADIOGRAPHIC EVALUATION

A radiographic study was performed on late bead separation from the po rous surface of clinically well functioning and radiographically stabl e Arthropor uncemented acetabular components, Of 104 cups in 102 patie nts, 11 (10.6%) showed bead separation from the porous coated surface, Bead shedding occurred at an average of 4.2 years (range, 2-7 years), In each case the phenomenon was progressive, In the group that shed b eads, there was a higher prevalence of acetabular radiolucencies (63.6 % versus 25.8%) and of osteolysis (45.5% versus 10.8%), These differen ces were statistically significant, The group that shed beads also had a higher polyethylene wear rate (0.21 mm/year versus 0.16 mm/year) an d were younger (49.5 years versus 59.5 years), All cups that shed bead s remained clinically and radiographically stable, Thus, the clinical impact of these observations is uncertain, However, the higher prevale nce of acetabular lucencies and osteolysis in these patients, in combi nation with an increased polyethylene wear rate, require thorough clin ical and radiographic followup to uncover potential loosening problems of these acetabular components.