An exploratory incision is always made to inspect the perforator before designing a propeller flap. In this case, a propeller flap is being elevated based on the posterior tibial system to cover a defect in the lower leg. Here the fascia is being divided and now you can see the perforator, which must be dissected down to the source vessel, so that when the flap is turned, it's a gentle twist rather than an acute twist. The Doppler is your friend and you can use the Doppler to listen to your perforator, make sure that it's still there at the end of your dissection, and then rotate the flap into the defect. And as mentioned in the text, rotate it in both directions, because sometimes the flap will be happier with a twist in one direction rather than the other. Check your Doppler again, inset your flap, and you're done.

propeller flap

perforator

posterior tibial system

Doppler device

lower leg defect