Christina Flygare's son had his summer all planned out: landscaping job, swimming and hanging out with friends, then band camp before his senior year of high school.

Instead, the 17-year-old Washington teen spends his days relearning to walk, shower and eat without his mother's help. He hopes to regain his fine motor skills so he can hold a pen and write in time for school in September.

His mother says she's just happy he's alive after he suffered spinal cord injuries in April at a trampoline facility in Bellevue, Washington. Flygare believes the owners and operators of Sky High Sports Seattle are responsible for her son's injuries and has filed a lawsuit seeking undisclosed damages for his care.

"It's devastating to see your child go from being a vibrant athlete -- laughing, playing, running and jumping -- to sitting on a sofa feeling down and gloomy because he can't do the things he should be doing," said Flygare, a single mother of seven employed as an office assistant.

Flygare and her son are one of 18 families in the Seattle area with negligence claims against Sky High Sports' Bellevue location. Of the 10 filed since 2010, Sky High claims four were settled by its insurance company, despite its desire to go to trial. Six more are pending, and the firm Osborn Machler plans to file eight more.

The families, who are all represented by Osborn Machler, allege that Sky High's "trampoline fun centers" are inherently dangerous in the way they are designed, maintained and supervised. But the lawsuits go beyond Sky High and Washington, sparking safety concerns over an industry that only seems to be growing. Even Orange County "Housewife" Alexis Bellino and her husband are apparently cashing in on the craze by opening a new facility in California billed as the largest in the United States.

Flygare and other parents claim the centers are accidents waiting to happen. Business owners, however, say trampoline use leads to fewer injuries than most sports and that it's up to parents to assess the risk.

Eric Beck, owner of two trampoline centers in suburban Chicago, advertises his injury rate on Xtreme Trampoline's website to help people make informed decisions, he said. Beck said his facility reports lower injuries than many common sports: about 2 per 1,000 trampoline jumpers. He pointed CNN to a 2002 study in the American Academy of Pediatrics Journal analyzing injuries in organized youth sports. The study shows injury rates equivalent to 15 per 1,000 players in football and 21 per 1,000 in soccer.

Like many owners and operators of trampoline parks, Beck opened his first facility about year and a half ago, after he visited another with his 6-year-old son. It was only a matter of time before his facility was slapped with a lawsuit, he said, because "everyone who owns a trampoline park in the United States will eventually get sued.

"Because this is a very fast-growing industry, the only ones who haven't been sued are the ones who haven't been around for very long. It's the way our legal system works."

Beck's trampoline center in Carol Stream was sued earlier this month along with Sky High Sports Niles, a subsidiary of Sky High Sports, by two different families. Both families accuse the centers of improper supervision and failing to enforce rules prohibiting more than one jumper on a trampoline at a time, attorney Mike Holden said.

"Double-jumping" can cause injuries as one person lands while the other attempts to jump. Both lawsuits allege that double-jumping contributed to leg fractures in 5-year-old girl and a 9-year-old boy in 2011.

"Fortunately, we're talking about broken bones and not paralysis," said Holden, whose firm, Romanucci & Blandin, is representing both families. "But it can easily degrade into that if these facilities continue to operate in such a way."

From training devices to 'backyard trampolines'

Trampolines were initially designed as training devices for gymnasts and acrobats and later, military pilots, whose bodies go through different orientations while in flight, said Dr. Gary Smith, president of the Child Injury Prevention Alliance and spokesman for the American Academy of Pediatrics.

They evolved into consumer products when manufacturers found ways to break them down into smaller parts at affordable prices, leading to the rapid expansion of backyard trampolines, he said.

Trampolines are a great source of aerobic exercise and help develop balance and coordination if used properly, he said.

"They're not inherently dangerous. It's about how you use them," said Smith.

"The best way to learn is to go down to local gym and do it under the training of gymnastic instructors and let them progress you through maneuvers," he said. "We really want to encourage people of all ages to be physically active. We just want them to do it in a smart way so they don't end up decreasing physical activity due to injuries."

Several public health agencies have issued advisories on "backyard trampolines" in homes but have yet to clarify a stance on trampoline facilities, which are unregulated by state or federal agencies -- often because they are neither mechanical nor electrical.

There were 92,159 hospital emergency room-treated injuries associated with trampolines in 2010, according to the U.S. Consumer Product Safety Commission, the latest year for which statistics are available. That figure doesn't specify whether those injuries in homes or at trampoline centers.

In a 2006 position statement, the American Academy of Pediatrics recommended "that trampolines should never be used in the home environment, in routine physical education classes or in outdoor playgrounds." They reaffirmed that position in summer safety tips this year, which advised that parents "should never purchase a home trampoline or allow children to use home trampolines." There was no explicit reference to trampoline parks.

The American Association of Orthopedic Surgeons also weighed in on trampoline safety advice in March after Yankees baseball player Joba Chamberlain suffered a career-threatening ankle injury while jumping on a trampoline with his 5-year-old son at a children's play facility in Tampa.

"Although trampolines can be fun for both kids and adults, they pose a high risk for injuries, especially when two or more people jump at one time," said AAOS spokesman and orthopedic surgeon John Purvis. "Orthopedic surgeons recommended that trampolines not be used in home environments or in outdoor playgrounds because of the high risk of injuries this activity."

Most injuries result from colliding with others, landing improperly or falling off or onto the springs or frames, the Consumer Product Safety Commission notes.