I really don't like doing surgery on hygromas. These are not problems with the skin or the fluid filled sac, it's more of an issue of physics and structure. The surgery site is hard to heal because of repeated trauma when laying, and they tend to get infected. I also don't like to drain them - what happened is the usual, they fill back up and there is a good chance of introducing bacteria and getting an infection.
I've found bandaging and "life style" changes to be as effective as anything (not always that rewarding, though). Bandaging a "donut" around the elbow can protect from further trauma and requiring the dog to always lay on soft surfaces is required (but VERY difficult to accomplish).
Sorry, no easy answer here.
Doug, DVM