[Acetabular revision for aseptic loosening in total hip arthroplasty using cementless cup and impacted morselized allograft].

PURPOSE OF THE STUDY

Impaction grafting can be used in cementless fixation with morsellized bone, bone graft, and hemispherical cup. The first goal of impaction grafting in revision of total hip arthroplasty is to transform segmental defects into cavitary defects and obtain a full compaction of the graft in order to restore the bone stock. The second goal is to achieve primary stability of the cup. The third goal is to restore the hip center of rotation with a cup anatomically located in the acetabulum. The aim of our study was to evaluate the results of a surgical technique with impacted morsellized bone graft and a cementless press-fit cup for the revision with defect type III according to the AAOS classification.

MATERIAL AND METHODS

We performed a retrospective study including 34 hip reconstructions during revision of acetabular aseptic loosening with type III AAOS acetabular defects. All the revisions were performed in the same center by two senior surgeons. Mean age at surgery was 58 years. There were 23 women and 11 men. All reconstructions were performed with a cementless cup and a morsellized impacted bone graft. The analysis of the acetabular defects was done preoperatively according to the AAOS classification. We analyzed postoperatively and at follow-up: position and stability of the acetabular cup, restoration of the hip center and graft integration.

RESULTS

Mean follow-up was 6.6 years (range 3-13 years). Complications included three dislocations, two trochaanteric nonunions. Two acetabular components were revised for septic loosening. According to the Kaplan-Meier survival curves, with endpoint criteria defined as acetabular cup removal, survival was 91.3% at 10 years (95CI: 86.3-96.3). The preoperative Harris hip score was 53 points (range 26-86) and at last follow-up 94 (47-100). Concerning the subjective clinical outcome, 96% of patients were satisfied or very satisfied at last follow-up. 100% of cups were considered stable at follow-up and bone integration was good in 100%. The center of rotation was located in anatomic position mediolaterally in 66% and in the craniopodal plane in 44%.

DISCUSSION

Restoration of bone stock is one of the main goals during hip reconstruction after aseptic loosening. Clinical experience in our series has shown the reliability of the impacted morsellized bone graft allowing relocation of the center of rotation and good cup stability. Biological fixation of the cup and graft integration seems good at mid-term follow-up. The cup that we used in our series combined the advantages of a press-fit cup and those of a reinforcement ring. The combination of this type of cup with morsellized bone graft seems to be a reliable solution for restoring bone stock, relocating the hip center, and stabilizing the cup in revision total hip arthroplasty with type III acetabular defect according to the AAOS classification.