As Israel tightens its siege, medical supplies in the Gaza Strip are running out, and doctors confront patients with unimaginable injuries. The orthopedist Hani Bseso operated on his niece Ahed’s leg, after a shell plowed through their home. Bleeding profusely, Ahed remained in an agonizing daze, as relatives carried her downstairs. Reaching a hospital was impossible. So Bseso amputated her…