Revision hip arthroplasty of massive acetabular defect, severe combined defect, or pelvic discontinuity is challenging. The purpose of this study was to determine the midterm outcome and survivorship of a new revision technique using cementless acetabular cup supplemented with a hook and three iliac flanges in massive acetabular defects.
From January 2000 to June 2004, we revised 17 severe acetabular defects, 14 combined defects and three pelvic discontinuities according to the American Academy of Orthopaedic Surgeons (AAOS) classifications, in which bone stock at the dome was not available to provide support for the cup. These revisions were performed using a cementless porous-coated hemispherical cup with a hook and flanges.
One patient (one hip) underwent resection arthroplasty due to infection 1 year after the revision. The remaining 16 hips were evaluated at a mean of 6.8 (range 5-9) years postoperatively. Thirteen acetabular components (81%) showed no migration and were stable with bone ingrowth. Three hips showed progressive medial and upward migration during the 18-24 months after the index revision, after which migration was not progressive. The Merle d'Aubigné hip score was 14.5 (range 12-18) points at the latest follow-up evaluation. Survival rate was 94.4% when revision for any reason was considered as the end point [95% confidence interval (CI) 83.9-100%] and 82.0% (95% CI 62.8-100%) when loosening of the cup was considered as the end point.
Results of this type of revision were superior to previously reported results of acetabular revisions with the use of various techniques and devices.