In this morning's Minneapolis Star Tribune there was an article about trampoline park injuries. As these parks have grown in popularity, the number of emergency room visits has also increased dramatically. In the five years ending in 2014 emergency room visits went from 581 in 2010 to 6932 in 2014.
Most of these parks require that the user or the user's parent sign an ironclad waiver before using the facilities. This waiver usually effectively insulates the park from any liability for injuries sustained while using the trampolines. These waivers have found favor with Minnesota courts.
About the only way that the undersigned has ever found to get around this is if the injury in question was caused by another user of the premises. That person might have coverage for their negligence under their homeowners policy.