Here’s the story of Coal, an eight-and-a-half year old hound had his left paw amputated because of cancer. He faced being put down because his other legs would be too weak to carry him. Instead of that, his owner Reg Walker spent £10,000 to fit him with a sophisticated bionic leg, which was designed to be compatible with Coal's own tissue. The titanium alloy used mimics animal hide, allowing the skin and the bone from above to seal the metal implant below without it being rejected by the body.