On a warm Philadelphia late-summer afternoon in 1997, the lights went out on Kevin Turner.

A vicious collision in a game against the Green Bay Packers knocked the NFL fullback silly. The Philadelphia Eagles’ medical staff cleared the cobwebs and sent Turner back into the battle. Turner remembers none of it.

But that’s how it was done back then.

Turner retired two years later, but he won’t be forgotten. As the NFL prepares for its annual marketing bonanza, next weekend’s Super Bowl, Turner and dozens of similarly ex-jocks are back to remind the world of the darker side of the nation’s most popular sport. Their stories will be front and center Thursday in Miami, when a panel of judges will decide if at least 10 recently filed negligence and class-action lawsuits involving ailing ex-players from across the nation — including Turner and former Dolphins Patrick Surtain, Oronde Gadsden and Lamar Thomas — should be combined into one all-encompassing case.

Their complaints are all a variation on the same theme: that repeated head trauma suffered during practices and games directly contributed to disabilities later in life — including memory loss, migraine headaches and depression, sometimes leading to suicide.

Furthermore, the suit alleges the NFL knew of the potential long-term health risks of repeated head trauma, but until recent years, did little about it. In Turner’s case, the league’s alleged negligence could ultimately cost him his life.

Turner’s health issues are more serious than most. He is dying from amyotrophic lateral sclerosis (ALS), the nervous disorder known as Lou Gehrig’s disease. Turner believes his illness is a result of the years of pounding he endured as a human battering ram, and researchers say it is a distinct possibility.

“I didn’t come upon this decision lightly,” said the 42-year-old Turner, who joined the growing lawsuit last week. “I finally decided that I’ve got to do something where this problem is actually taken seriously.

“[The NFL] is putting on a good front now, changing some rules, bringing up the awareness of it,” he added. “But had they done that 20 years ago, my life might be different, and those of lots of others.”

Depending on the doctor, Turner either has a couple of years to live, or a couple of months.

Either way, he believes pro football will end his life prematurely. In that way, he would share a fate with former Chicago Bears safety Dave Duerson, a once-successful businessman who fatally shot himself in the chest in his Sunny Isles Beach condo last February.

In his suicide note, Duerson beseeched his family to “please see that my brain is given to the NFL’s brain bank.” The family did as instructed, and researchers discovered he suffered from chronic traumatic encephalopathy, a progressive degenerative disease of the brain caused by repeated head trauma. His death helped elevate the NFL’s concussion problem onto the front page.

Now, Turner and his fellow litigants are demanding unspecified damages for what they call a decades-long pattern of negligent and fraudulent behavior by the NFL.

They are represented by the powerhouse Miami-based law firm Podhurst Orseck. The firm is also behind a separate class-action lawsuit, filed this week on behalf of NFL players who have suffered repeated blows to the head, but have not yet experienced long-term physical and mental deterioration. Their suit seeks NFL funding for baseline and diagnostic neurological exams to detect possible brain damage.