Are you having a min invasive surgery? (Often doctors don't mention that when giving you choices of types of surgery and I often wonder why not) anyway for some surgeries, usually min invasvie or full sternum REDOS (usuall multiple) they use either the groin or neck/collar bone area for the heart lung machine. They need to use it for min invasive because the incision is too small to fit the tubing for the bypass machine and do the work they need to. and the reason they might need it for REDOs is sometimes it is safer to put the person on bypass before they open their sternum. We knew going into Justin's 4th and 5th OHS it was a possibility they would either use his neck or groin area for the bypass and at preop they did an ultrasound of the right and left side of both areas looking for access, Justin said IF they had a choice he rather have his groin used then a 2-4 inch scar at his collorbone and thats what they did for his 5th surgery.
Justin had more pain with that incision than the sternum,(which he says isn't real pain) probably because you move it alot when you are doing your walks ect. it still wasn't horrible pain. Also he had quite a bit of his upper thigh numb for weeks/a couple months and I've heard other say the same thing who had bypass hooked up there.