Whether or not the implant is cemented. At present it is hoped that the new, uncemented implants will last longer than cemented ones. The design of the implant. Small abrasion particles from the implant may play a role in implant loosening. Some designs shed more particles than others.
Dislocation means that the metal ball slips out of the plastic socket.
In the first six weeks after the surgery, the ball is only held in the socket by muscle tension. During this time, before scar tissue forms around the ball, and before muscle strength returns, the hip is more likely to dislocate. The physical therapist will teach you what positions to avoid, and how to safely use your hip replacement during this early phase of your recovery. Revision hip replacements, replacements in people who are grossly overweight and replacements in people with poor muscles are more likely to dislocate. Occasionally patients develop repetitive dislocations, requiring a brace to be worn for several months to prevent further dislocation.