Revision total hip arthroplasty for large medial (protrusio) defects with a rim-fit cementless acetabular component.

Seventeen patients (19 hips) with protrusio acetabuli resulting from a failed total hip arthroplasty, large medial bone defect, and an intact bony rim were treated with an oversized cementless acetabular component and medial morcelized allograft. An average of 55% of the revision component was not supported by host bone. At an average follow-up of 2.8 (range 2-6) years, none of the acetabular components required revision for loosening. The average cup position preoperatively was 10.5 mm medial to Köhler's line and postoperatively was 6.8 mm lateral to Köhler's line. Despite very large medial defects, reconstructions with this technique remained stable.