The Use of Structure Transplants With Revision Endoprosthetics in Conditions of Significant Acetabular Osteolysis

Abstract

To study long-term results of acetabular revisions with use of structural bone allografts in severe acetabular bone loss (2C, 3A and 3B by W. Paprosky classification). Materials and Methods One hundred eighty-three acetabular revisions with the use of bone allografts were performed; of these, structural bone allografts were used in 21 cases. In 7 cases, total revisions were performed; in 14 cases, isolated acetabular revisions were performed. In 20 cases (95%), the reason for revision surgery was the aseptic failure of the acetabular or both components, in one case it was the sequel after deep infection. In three cases (14%), before implantation of the acetabulum, bone grafting was performed with structural allografts-the femoral headswith screw fixation. In 18 cases (86%), structural allografts were tightly impacted in a previously prepared bone stock followed by the installation of the acetabular component. Results. This is an analysis of the long-term results of the use of structural allografts in 16 acetabular revisions with massive bone defects. The mean term follow up in the group was 75.35±31.1 months (7-185 months). Of 16 cases of acetabular revision in the group, in three cases (18.75%) trabecular remodelling of allografts was noted, in three cases (18.75%) there occurred trabecular incorporation, and in ten cases there were lack of changes in comparison with postoperative X-rays. In five cases (31.25%), stage I resorption of transplants was recorded according to Sporer (lack of resorption); in six cases (37.5%) stage II resorption (less than 25%), in three cases (18.75%) stage III (25-50%), and in two cases stage IV resorption was noted (over 50% of transplant). Type I stability of Burch-Schneider cage (according to the Gill evaluation system) was revealed in three cases-lack of osteolysis around construction and screws. Mean change of the rotation centre was 0.23 mm; mean change of the inclination angle was 0.1 mm. Type II stability was found in three cases-there was an increase of the osteolysis line upwards and medially. Mean change of the rotation centre was 9.6 mm; mean change of the inclination angel was 10.9. Type III stability was not noted. Evaluation of the condition of press-fit fixation components (according to Moore) showed that in five cases there was lack of component migration, mean change of the rotation centre was 3.75 mm, and mean change of the inclination angle was 1.4. In five cases, there was component migration, mean change of the rotation centre was 5.44 mm, and mean change of the inclination angle was 14.06. In two cases out of 10, there was mechanical damage of the components (screw fractures) Conclusions. The use of structural allografts for filling of massive acetabular defects in acetabular revision is an effective method for the restoration of the bone stock, which allows to restore the centre of rotation and to install the acetabular component in its correct position.