Aims: The purpose of this study is to evaluate clinic and radiological results in acetabular revision using hemispherical hydroxyapatite (HA)-coated cups and morselized allograft in the presence of sever bone defects (Paprosky type IIIA). Methods: From a serie of 218 patients having revision total hip arthroplasty between1995 and 1999, 42 hips in 42 patients were included in this retrospective study. The inclusion criteria were:

Ð Presence of sever bone loss without pelvic discontinuity (Paprosky type IIIA).

All revisions were carried out by the same surgical team using a posterolateral approach. Morselized allograft was used in all cases. The mean age at the time of revision surgery was 70 years (range, 48 to 84). The mean follow-up was 52 months (range, 36 to 81). In 39% of the cases a extra large cup (more than 60 mm) was used. Results: the average Merle dñAubignŽ score rose from 7.3 points preoperatively to 17.2 points at follow-up (90% of the patients were pain free). All the cups remained radiologically stable at follow-up. Partial resorption of the allograft without jeopardising implant stability was detected in 4 cases (10%); all the rest showed radiological consolidation and remodelling of the medial wall of the acetabulum. Conclusions: these results strongly support the use of hemispherical HA-coated cups, combined with morselized allograft, in acetabular revision even in the presence of major acetabulum bone loss.