My PS mentioned a shot of cortisone to help some of the scar tissue. Why is this and what will this do?

A Injections of Cortisone or Kenalog can help break up excess tissue.  It is a common remedy to inject steroids such as these and also is used primarily to reduce swelling and inflamed tissue.  Although care must be taken regarding excess use of these injections as it can break down the tissue too much.