The assessment of large allografts in acetabular reconstruction surgery is notoriously difficult. Because of their invasive natures, methods such as tetracycline-labeled histological examination are not recommended. Radio-isotope studies are unreliable in assessing the degree of incorporation because labeled tissues remain hot for extended periods. CT scans are impractical because of the scatter generated by the metallic prosthetic components.

We used DEXA to assess the quality of large acetabular bone grafts immediately after surgery and at regular intervals thereafter. Software programmes were used to subtract the prosthetic components and give values for the remaining bony structure. DEXA results confirmed the initial adequacy of our grafting techniques. Serial scans showed the response of the grafts to both revascularisation and loading. Increases in high-load areas were higher than in low-load areas, reflecting the response of live bone to in vivo stresses. There were also changes reflecting the ongoing revascularisation of the grafts. These findings were born out by radiographs.

DEXA is useful in assessing the incorporation and biological responses of large allografts in revision arthroplasty.