A seriously misguided Broadway musical adaptation of the much beloved 1993 film comedy “Groundhog Day” (in which a self-centered, sarcastic weatherman keeps reliving the same day over and over until he can redeem himself) has nevertheless yielded the most inspiring backstage story of the year.

On Friday, just three days before opening night, leading man Andy Karl (who previously starred in “Rocky”) sustained a serious knee injury mid-performance. The Saturday matinee was canceled and Karl’s understudy went on that night.

After much uncertainty about whether opening night would be delayed and who would play Phil going forward, the producers confirmed on Monday at noon that the musical would open as scheduled that night with Karl.

Had Karl not appeared on opening night, he would not have been eligible for a Tony nomination. Last week, Karl won an Olivier Award for his performance from when the musical premiered in London.

My press performance was canceled following Karl’s injury, so I attended on opening night. Karl wore a knee brace but otherwise showed no sign of injury in a physically demanding role where he is virtually never offstage and always on the move.

The musical — which has direction by Matthew Warchus and songs by Tim Minchin (who previously worked together on “Matilda”) and a book by Danny Rubin (who co-wrote the film’s screenplay) — is a loud, bizarre, over-energized and tiresome misfire. Minchin’s pop-rock score is unmelodic and unmemorable, and the high-tech staging is so busy that it turns the film’s quiet charm into a frenzied parade of silly gags.

Compared with Bill Murray’s low-key performance in the film, Karl throws himself into the part with an over-the-top energy. He makes Phil into such an obnoxious jerk that the audience has little incentive to care about him. Meanwhile, Barrett Doss does not make much of an impression as Rita, Phil’s co-worker and potential love interest.

Years ago, Stephen Sondheim considered turning “Groundhog Day” into a musical but ultimately decided that the film “cannot be improved.” It looks like he was right.