So very sorry to hear that. I hope your knees are better and I'm sure the recipient understood....wow, that's sad!
I've always found it to be really the "last step" when delivering a cake....before taking the cake out of the vehicle, walk the walk! I walk all the way into the venue. Without the cake. Remove any obstacles or whathaveyou. THEN go get the cake and bring it in
Even so, STILL you may have to watch for fast-trotting servers
(I almost T-boned a server with a 1/2-sheet, double-layer and torted cake.)