Abstract: The present invention is related to a prosthesis, in particular a revision prosthesis, for repositioning and fixating acetabulum fractures. The prosthesis comprises a cup member (1), a hook member (2) and a hook retraction member (3). The cup member is formed and configured to be fixable into an acetabular cup. The hook member is formed and configured to be fixable onto an edge of the acetabular cup. The cup member and the hook member are formed and configured to be retractable into one another. The hook retraction member comprises at least one cable arranged and configured for retracting the hook member into the cup member.