Missionary style is a rarity for us, but once while engaged in doggie style for a long enough period, we moved all the way up to the front of our bed and just seconds prior to climax hit our heads smack dab on the headboard (which is ridged). We were quite a sight to see for a couple of days!
Since then we angle ourselves on the bed when doing doggie style. Now our only problem is risking a broken neck from hitting the floor when we are out of control!