Paper# II-4

CEMENTLESS ACETABULAR REVISION: EVERY MILLIMETER COUNTS

Stephen Walsh, MD

Montreal, QC

Co-Author

Michael Tanzer, MD, FRCSC

Revision acetabular arthroplasty commonly employs cementless acetabular components augmented with screw fixation. Long-term stability depends on initial rigid fixation and eventual bone ingrowth. A minimum of 50-70% host bone coverage (ideal minimum 70%) is commonly cited as a guide to ensure adequate host bone contact. However, the actual ingrowth surface area in contact with host bone varies based on cup size and design in addition to the percent host bone coverage. The purpose of the current investigation is to delineate the porous ingrowth area covered by host bone that will result in predictable long-term stability. Based on a review of published literature, a guide was developed to determine the necessary percentage of ingrowth surface area in contact with host bone providing acceptable failure rates ranging from 1.4-2.5%. This will allow the surgeon to modify and generally decrease the host bone coverage minimum based on the size and design of the particular cup in use.