VIABILITY OF THE ACETABULAR BONE BED AT REVISION SURGERY FOLLOWING CEMENTED PRIMARY ARTHROPLASTY

Loosening of total hip replacements is often associated with severe lo ss of periprosthetic bone. The notion exists that the remaining bone i s sclerotic, avascular, and displays little osteogenic activity, and t hat it therefore potentially compromises the revitalization of bone gr afts used to restore bony defects. To verify this opinion we studied t he bone characteristics in acetabular bone biopsies taken at primary t otal hip arthroplasty (PTH) and revision total hip arthroplasty (RTH) for a cemented PTH. In 6 PTH patients and in la RTH patients, acetabul ar bone biopsies were taken from the roof, the center, and the lower r im of each acetabulum. Specimens were evaluated by light microscopy an d histomorphometrically measured for specimen size, bone area, perimet er, active osteoid perimeter, number of vessels, and osteoclasts. The vascularity and vitality appeared to be comparable in the RTH and PTH bone biopsies. However, the trabecular organization of the RTH bone di ffered from that of the PTH: biopsies. In the PTH biopsies, the trabec ulae were running perpendicular to the subchondral bone layer, whereas in the RTM biopsies the layers of bone were oriented parallel to the implant surface. There was abundant remodeling activity in the RTH bon e, with large quantities of active osteoid and osteoclasts. These hist ologic parameters differed, but not statistically significant, from th e PTH biopsies. In conclusion, we found that at revision, the acetabul ar bone was viable with sufficient vascularity and remodeling activity to provide an acceptable recipient host bone bed for revision surgery combined with bone grafting.