The theater adage “break a leg” has new meaning this week at Salt Lake City’s Pioneer Theatre Company.

During Monday’s performance of the jukebox musical “Mamma Mia!,” lead actor Coleen Sexton fractured her left fibula while stepping off a trunk on set.

Through tears, Sexton was able to finish the song — “Dancing Queen,” ironically enough — then the cast took an early intermission to assess the situation.

The show must go on, of course. Sexton’s ankle was stabilized and she performed the rest of the show from the sidelines. For her determination, the empathetic audience gave her a standing ovation.

There was a special rehearsal the next day to adjust the choreography; the costume shop fixed Sexton’s onstage clothing to fit over her protective boot.

That night she was back onstage — albeit with crutches — singing “Super Trouper,” “Winner Takes It All” and all the other ABBA songs, which inspired the original Broadway show and led to the 2008 blockbuster movie starring Meryl Streep and Pierce Brosnan.

Chris Lino, Pioneer Theatre Company’s longtime managing director, gets onstage before each show and explains why Sexton is in a boot and crutches.

Now, Instead of dancing with the cast during “Money, Money, Money,” Sexton leans against a table and then is lifted and carried around; during “Dancing Queen,” while her friends dance in her bedroom, she sits on the bed and performs.

She plans to perform that way through the end of the run on May 26.

“I’m sitting a lot, but I can still give the audience something they enjoy,” said Sexton, best known for her portrayal of Lucy Harris in the Broadway production of “Jekyll and Hyde.”

(Courtesy photo|Pioneer Theatre Co.) During Monday's performance of "Mama Mia," Coleen Sexton (center) jumped off the trunk during the song "Dancing Queen" and broke her ankle. She will continue to perform using a boot and crutches through May 26.

She couldn’t do it, though, “if it wasn’t for the cast and crew, who have been so supportive and willing to modify movements and staging around this unfortunate incident,” she said during a telephone interview while icing her foot. “It’s the perfect example of a good company rallying behind you.”

Fortunately, the role of Donna, a middle-aged single mother preparing for her daughter’s wedding, is more singing than dancing, said PTC artistic director Karen Azenberg. That made it easy not to call in an understudy.

“It was a crazy day,” she said, “but I don’t think anyone in the cast or on our staff seriously considered another option. We wanted our audience to see Coleen doing that role.“

While broken toes and sore backs are common in live theater, Sexton’s onstage injury is the most unusual one Azenberg has seen in her six years at Pioneer.

“We’ve had some crazy stuff, but not quite to this degree,” she said.

In 2011, though, during the run of “Next to Normal,” actor Judy McLane suffered severe seasonal allergies that affected her voice.

To save her voice “she went around with a white board and wrote things down,” Azenberg said. “She wasn’t allowed to speak a word during the day.”

It even happens on Broadway, said Azenberg. Last year the lead actor in “Groundhog Day” injured his knee. He wore a knee brace and muscled through the role for six weeks.

“That’s why the people we hire are so valuable,” she said. “They are able to cope with whatever comes their way.”

DANCING QUEENS

Pioneer Theatre Company’s production of “Mamma Mia!,” the feel-good ABBA jukebox musical set on a sun-washed Greek island, plays through May 26.

When • Monday-Thursday, 7 p.m.; Friday-Saturday, 7:30 p.m.; and Saturday matinee 2 p.m.

Where • Simmons Pioneer Memorial Theatre, 300 S. 1400 East, Salt Lake City.

Tickets • $42-$64 in advance; $5 more day of show; half-price tickets for K-12 students on Monday and Tuesday; at 801-581-6961 or pioneertheatre.org