I'm 10 mos out of surgery and remember this quite well. My after surgery nurse suggested imagining a box that only goes to the top of your head, down the shoulders and to the waist. No reaching above this or to the side either. As for at home attire, she suggested I wear very large t'shirts,( I wore my husband's XL) and this worked very well. They don't recommend button up shirts, so no reaching backwards. I also wore sweats as pants and slip on shoes, since I got pressure sores on both heals from the long surgery.
She actually showed me how to get dressed while I was still in the hospital.