You've had an open wound for almost 2 years, and it they haven't considered it's a pyoderma?! This shocks and saddens me, that you haven't had this sorted. Whatsort of size is the wound and have you had any treatment for it yet?
I had an ulcer on the side of my calf measuring around 7 cm across a few years back. My GP first tried treating it with antibiotics, and told me to keep it open to the air to dry it out. This caused the worst pain I have ever felt - worse than the pain I'd ever had to cope with in my guts. I went back to the surgery - and saw a different doctor, who saw immediately that the would was necrotic, and immediately referred me to a Dermatologist at my nearest main hospital (Addenbrookes, Cambridge at the time).
The dermatologist took a biopsy that same day. I can't really remember the injection - I'm sorry, I don't have a needle phobia, so it didn't factor in, but now you mention it I remember that I did have a local anaesthetic. They laid me down on a bed, and a nurse held my hand. It was over in no time and they took a tiny nick ou the side of the wound. They then sent the biospsy off to the lab - they were checking that there wasn't an infection. If it is a pyoderma then they won't manage to grow any pathogens from the biopsy. However, in my case they didn't wait to see if it was a pyoderma before they started treating it. They immediately put me on a course of prednisolone, and I had to treat the wound with a big squirt of steroid cream daily, before covering it with a special ulcer dressing. It took a long time for the wound to heal, but it did steadily get better over a number of weeks.
You must try not to worry about an injection, it is a very small price to pay if you want to get this wound healed.
I hope this helps! Let me know how you are getting on.
