Reply to the Letter to the Editor: Stem Cells Combined With Platelet-rich Plasma Effectively Treat Corticosteroid-induced Osteonecrosis of the Hip. Issue 5 (May 2018) - Houdek, Matthew T.; Wyles, Cody C.; Collins, Mark S.; Howe, Benjamin M.; Terzic, Andre; Behfar, Atta; Sierra, Rafael J.