"...had a blast at the 'Stepmom' shoot, it's a great song, full on rock and roll number.
Banged my knee badly while doing this sliding step on the floor, hope it just a bruise and passes. (I) hate injuries, they are very annoying and come in the way of work, " Arjun posted on his Twitter page.
The actor was shooting the song with Kareena and Kajol for the movie, being directed by Siddharth Malhotra.