Your immune system rejects any implants. If you lose a limb, you can either wear a strap on prosthetic or it may be re-grown or replaced from your own tissue You will also reject organ and tissue transplants from other sources. A replacement must be grown from your own tissue. If you ARE implanted with foreign material, you must make a Constitution check every week starting at Easy and increasing in difficulty each subsequent week. Failure means that the implant is rejected. An external implant such as an arm or leg may simply become necrotic and fall off, an internal item will cause you to become deathly ill until it is removed or you die.