Healing deep wound in leg

My mom who''s 83 has excessive water weight on and the skin on her legs are tight. She''s on a water pill. The other day she was getting out of bed to get into the wheel chair, pivoted and jammed her leg into the brake handle of the wheel chair which punctured the skin and went deep into her leg. It bled for a while and now it just keeps draining clear fluid? The wound is about the size if your little finger wide and almost a perfect circle.. She''s allergic to Neosporin, Bactrium and most skin creams from the "ium family. She has ulcerated ankles and this wound is a bit below the knee on her shin area. How can we resolve this? She is not in too much pain and it doesn''t look infected, we have been flushing with saline and using X-form covers with gauze. How do we heal it?
Best,

Ron