In 1983, Def Leppard became established as a superstar musical attraction. The British quintet's "Pyromania" album sold 6 million copies in the United States alone on the strength of the hits "Photograph," "Rock of Ages" and "Foolin'," and stayed on the charts for nearly two years. Only Michael Jackson's "Thriller" kept the LP out of the No. 1 spot.

But seldom in rock history has a band faced such a tough time following up a successful record. A litany of crises led to a four-year delay.

First, drummer Rick Allen lost his left arm in an automobile accident. Then there were false starts with producer Jim Steinman when first choice Robert "Mutt" Lange was unavailable to do the record. At one point, vocalist Joe Elliott had the mumps while Lange was also in an accident.

But they persevered through the traumas, and "Hysteria," the band's current best-selling album, is the outstanding result - 12 shimmering tracks of hard rock (most notably "Animal," "Pour Some Sugar On Me" and the title track) that have re-established Def Leppard as one of the premier rock acts of the '80s.

Now the group is concentrating on a world tour, including two dates at Denver's McNichols Sports Arena tonight and Saturday. Elliott acknowledged his band's reclaimed status in an interview before a recent show in Cincinnati.

"Nowadays, every kid knows what Def Leppard is basically all about, whether he's heard of us or not," he said. "It takes time for a band to discover a musical identity, but we knew we had found ours as soon as people started copying it. While we were away, there were bands coming up that had a Def Leppard-ish sound to them.

"Back when we were still trying to establish ourselves, we had to get across that we weren't just a blatant heavy metal band, because we've got too much variety to just be heavy metal, too many key changes, too many tempo changes.

"There are lighter shades to our music. I don't like the idea of being bagged. We're gonna do that ourselves. We always call ourselves a high-energy rock 'n' roll band."

Of the many factors that delayed the making of "Hysteria," Elliott said the most devastating was Allen's injury. But Allen was determined to continue playing with one arm - the drummer developed a left-foot technique to go along with a specifically designed Simmons electronic drum kit.

"Had he not been able to play the drums any more, there's no doubt the band would have carried on," Elliott noted. "But while the band wasn't going to split up because of his accident, there was also no way we were going to kick the guy out because of his accident.

"It became an easy decision for the rest of us. We palmed it off. People put us up as being great heroes, and I suppose there is something to be said for sticking with a guy. But we basically put the ball in Rick's court, and he's the hero. He said he wanted to try and come back, and he succeeded."

Allen's ability to play can be witnessed in concert, as the current tour has been designed in the round, and the abnormal set will be captured on film in Denver. The group is filming the McNichols concerts for a video of "Pour Some Sugar On Me" and perhaps a long-form video release.

The band members are financing it themselves (We couldn't get the record company to pay for this one," Elliott laughed), but the project offers them a chance to commemorate their massive stage show for their following. They're acutely aware of how frustrating the long wait for the "Hysteria" album and tour was for fans, and the band wants to make up for it, which is why "Hysteria" contains more than an hour's worth of music, and the B-sides of singles feature previously unreleased songs.

"During all of the problems, we'd get mail besides the usual God-I-love-you letters," Elliott recalled of the group's hiatus. "A few would say, 'We'll wait for you forever.' And others would say, 'Well, there is a limit to our patience.' And then others would say, 'Have you ever heard of a band called Bon Jovi?'

"But we didn't let anything worry us. We just knew that the most important thing we had to do was put out a good record; give value for the money. The one thing we can never be accused of is flooding the market.

"We're not even thinking about studio time right now because we're touring. But I can give you my word that it won't be four years before the next album."