Observations on retrieved polyethylene glenoid components.

It is recognized that retrieved polyethylene hip and knee components may undergo substantial changes from their preimplantation form. Little information is available, however, regarding retrieved polyethylene glenoid components. We report on 39 glenoid components removed at an average of 2.5 years after implantation. Of components for which clinical data were available, the commonest reason for the revision arthroplasty was loosening of the glenoid component; many components also showed glenohumeral instability. The articular surface contours of most of the components were altered. Of components, 28 had obvious erosion of the rim, 27 had surface irregularities, 11 were fractured, and 9 had central wear. These observations in retrieved glenoid components point to the potential of polyethylene for deformation in vivo, especially when the mechanics of the arthroplasty are compromised.