The cat leg implants are custom-made. The surgical team drills the pegs into the cat’s ankle bones on each leg. They then coat the prosthetics with hydroxyapatite, a calcium phosphate similar to human hard tissues, to encourage bone cells to grow onto the metal. The skin then grows over an “umbrella” at the end to prevent potentially fatal infection, and the peg protrudes through the bone and skin, which allows the custom-built paws to be attached. Lucky cats.