The contact had a dealer loaner vehicle, a 2015 GMC Terrain. The contact stated the liftgate raised up extremely fast and caused the hydraulic on the passenger side to detach. Once the hydraulic fell, the liftgate hit her in the head, and she became unconscious. A random person assisted contact. Once she became conscious she drove herself to an emergency. The contact was diagnosed with major injuries of spinal whiplash and consciousness. The contact had been scheduled for a neurologist. The dealer was notified of the failure; however, were not of assistance. The dealer informed the contact to notify GMC of the failure. The manufacturer has not been notified. The approximate failure mileage was 102,000