Why aren't artificial bones used?

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Call me crazy but the current process of leg lengthening seems a bit archaic. I don't understand why they can't use artificial bone materials to extend the bones? Some people have their entire femur's replaced.

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I'm not seeing how soft tissue is the issue here. You stretch it with normal lengthening anyway, so? And the process is slow because of your bone needing to heal not because of your soft tissue, no? Don't sumo wrestlers purposely stretch/break their hamstrings in one instance?

As far as people wanting to be taller thousands of years ago...