Shelf life of prostheses (implants) for joint replacement is important. But it may not be as important as two other factors. The first is whether or not the implant has been sterilized properly.
Studies show that sterilization using the gamma radiation-in-air method may be linked with preserving the thickness of the insert. Polyethylene (plastic) tibial bearings also hold up better with a second type of sterilization (nonradiation method).
The second factor is implant design. Too long of a shelf life may mean using outdated implant designs. With ongoing research, scientists have been able to find ways to improve the design.
You surgeon will double check the type of implant and match it to your specific joint and activity needs. It doesn't hurt to ask your surgeon more about the details of the implant selected for you.