Burpee form

I tried to do burpees for the first time tonight and when I bring my knees forward from the plank position, my feet come together and my knees go out on either side of me. All the pictures I can find of form show the knees coming directly under your chest. Any tips on modified versions or how to adjust my knee placement? I don't have cartilage in my right knee so want to keep my form on point as much as possible.