The statute of limitations in Pennsylvania is 2 years from when you knew you were injured or from when you reasonably should have discovered the injury based upon the signs and symptoms associated with the injury. I believe that you would have a difficult time convincing a jury that you were not aware that somethinfg was wrong for the last 12 years. However, every case is different and you should consult with a local attorney specializing in medical malpractice cases.
Just to be safe, check with Bill Caroselli in Pittsburgh.
Please note that these answers are provided as a community service and are not meant to create an attorney-client relationship.