Fig. 4

Indications leading to surgery with the “cup-in-cup” technique. (A + B) Recurrent dislocation; (C + D) polyethylene wear, as seen by the decentralized head within the cup (black lines indicating the asymmetry); (E + F) periprosthetic fracture necessitating both stem revision and cup revision with the “cup-in-cup” technique in order to prevent dislocation