Say you've just had ACL surgery. Or you're recovering from a bad break. Or, worse, you suffer a stroke, or MS, or spinal or neurological damage. Regaining the power to walk is one of the toughest things you can do, and it may be impossible without a crutch, rail, or physical therapist to lean on. The AlterG Bionic Leg—straight out of the sci-fi future—may be the answer you've been dreaming of. I should know. I tried it.