Board Thread:Theories and Speculation/@comment-3568954-20141209130421/@comment-5407586-20141209135959

And what I'm saying is that Naruto, without Hashirama's artificial arm that Tsunade implanted into him, would never be able to use Wood Release. Kakashi says: "When you mix two basic natures together, you create a new one…that is called a kekkei genkai", and Yamato in that very same chapter says: "If you can use more than one nature, it's no big deal using them separately…however, it's a whole different story using them together".