I Have Had Some Wounds On My Arthritic Toe Since

I have had some wounds on my arthritic toe since June. Doctors were going to do a biopsy....but now want to do an aspiration into the joint. They have not fully explained their reasons for changing their mind...(ie. my dermatologist, rheumatologist, and vascular doctor. I want to know more about this procedure, and the reasons why I have these wounds that won't heal.