Revision of the acetabular component without cement after a previous acetabular reconstruction with use of a bulk femoral head graft in patients who had congenital dislocation or dysplasia. A follow-up note.

BACKGROUND: Revision of an acetabular component that has failed after a total hip arthroplasty in which a bulk femoral head autogenous graft or allograft was used as a structural graft for acetabular reconstruction is an uncommon but complex and challenging procedure. We previously reported the results for seventy hips at an average of 16.5 years after a total hip arthroplasty in which an acetabular reconstruction had been performed with a femoral head graft. In the present study, we evaluated a subset of nine hips from that series that had a subsequent revision of the acetabular component without cement. The purpose of the current study was to assess the usefulness of the bone graft in this revision.

METHODS: The nine patients (nine hips) were followed clinically and radiographically for an average of seventy-six months (range, sixty-one to 114 months) after the index revision. In six hips the autogenous femoral head graft previously had been bolted to the lateral side of the ilium, and in one hip the femoral head allograft had been affixed in this manner. In the two remaining hips, the allograft had been placed within the acetabulum. The hips were classified according to the extent of acetabular bone loss, with use of criteria described previously. Three hips had stage-I bone loss; four, stage-II; and two, stage-IIB. A porous-coated hemispherical acetabular component was inserted without cement and fixed with screws in each hip. At least 70 percent of the porous coating was in contact with viable bone.

RESULTS: At the time of the latest follow-up after the index revision, all nine acetabular components were functioning well without loosening or osteolysis and none had been revised. The average Harris hip score was 77 points (range, 61 to 98 points) compared with 49 points (range, 27 to 96 points) preoperatively. One hip had had revision of the femoral stem, and another had had exchange of the acetabular liner because of recurrent dislocations. There was no additional resorption of the residual bulk graft that was in contact with the metal shell in any hip.

CONCLUSIONS: In this small series of complex acetabular revisions, the healed bulk graft provided valuable additional bone stock for the support of an acetabular component that was inserted without cement. Insertion of the acetabular component into the available bone, which consisted in major part of host bone and in minor part of united revascularized bulk graft, resulted in a well functioning hip after an intermediate duration of follow-up. In all except two hips, the enlarged bone stock allowed insertion of a larger acetabular component than had been used previously.