TREATMENT OF TYPE-III ACETABULAR DEFICIENCIES IN REVISION TOTAL HIP-ARTHROPLASTY WITHOUT STRUCTURAL BONE-GRAFT

The use of structural bone allografts has been advocated for the recon struction of type III acetabular defects, but the results reported for this method have shown revision rates from 20 to 30% and failure rate s averaging 50% at short-, to intermediate-term follow-up periods. A p rospective study was under taken to determine the results of reconstru cting type III defects without structural allograft and to compare the results using spherical components with the results using eccentric c omponents. Quantitative inclusion criteria were developed and applied to all hips undergoing revision arthroplasty between 1987 and 1991. Tw enty-one hips (20 patients) were identified and included in this study . An evaluation protocol including radiographs, and for defects greate r than 30 mm, computed tomography scans and three-dimensional models, was used. At an average follow-up period of 46 months, 19 hips (18 pat ients) were evaluated. Hip scores of these patients improved from 46 t o 75. The location of the hip center was improved to a greater degree in those hips with revised to eccentric components, but implant stabil ity was poor. Overall, the mechanical failure rate was 26%, the clinic al failure rate was 16%, and the revision rate was 11%. These results compare favorably with the results of reconstruction using structural graft al the same length of follow-up time. Good results can be achiev ed by reconstructing type In defects without structural allograft if a cementless spherical component can be placed in stable position on ho st-bone.