APPOSITIONAL BONE BRIDGING OF PRIMARY GAPS IN THE DOME AREA OF UNCEMENTED, POROUS ACETABULAR COMPONENTS

Reported here are two cases of primary hybrid arthroplasties using a c emented stem and an uncemented, porous acetabular component. Because o f the configuration of the acetabula, a residual central gap remained after implantation of the socket. Unimpacted grafts were used to fill the spaces. The gaps, amounting to 4 to 5 mm on the postoperative radi ographs, had disappeared at the 30-40-month follow-up examination, wit h no radiolucent lines at the bone-implant interface. Both sockets wer e evaluated by roentgen stereophotogrammetric analysis for 2 years, an d by using this technique for detecting micromovements, central migrat ion as a reason for the disappearance of the gaps was precluded. Bony apposition of primary gaps of up to 5 mm in the central area of well-f ixed porous acetabular components seems possible.