What is the average life of a hip replacement? what causes them to wear out?

Hip prosthetic life: Today's hip implants should last 20 to 30 years. But factors such as activity and patient size may shortened the life expectancy.

Hip replacements rarely wear out. The materials themselves are very durable. If the liner does wear out, it can be replaced without removed the implants in the bone. Other issues can cause hip failure (infection, loosening, instability, others- but these are also infrequent).