Bead loosening from a porous-coated acetabular component. A follow-up note.

Beaded porous-coated implants are commonly used in total joint arthroplasty. In this study, the authors extended the follow-up period for the Davey and Harris study of bead loosening in beaded cementless acetabular components. When 56 primary total hip arthroplasties were first reviewed, at an average of 2.5 years after surgery, the incidence of bead loosening was 8.9%. Reevaluation at a mean of 4.5 years after surgery revealed that the incidence of loosening had increased to 19.6%. Bead loosening was associated with acetabular migration in one component and a broken screw in a second. In the absence of loose beads, there were no broken fixation screws or socket migration. Radiolucencies at the bone-implant interface were seen in association with loose beads in only one case. Although long-term implications of bead loosening are not clear, bead migration may increase the possibility of macrophage response to metallic debris.