It was at that moment that Thorin had stood from where he had been perched near the bottom of the tree, raised Orcrist, and charged down the trunk directly towards Azog.

"Thorin!!" Kili and Fili had shouted after him, they could not reach him to go to his aid, only watch in horror as Azog kicked the warg into a run and hit the dwarf prince with a powerful swing of the mace he held in his hand, sending Thorin crashing to the ground.
"Thorin, no..." Balin breathed softly as he too watched, only praying that Thorin would get up again.