In a medical negligence claim against a Louisiana doctor practicing in a specific specialty, the plaintiff has the burden of proving, by a preponderance of the evidence: (1) the degree of knowledge or skill possessed, or the degree of care ordinarily exercised by physicians licensed to practice and actively practicing in the same medical specialty as the defendant doctor; (2) that the defendant doctor either lacked this degree of knowledge or skill or failed to use reasonable care or diligence, along with his best judgment in the exercise of that skill; and (3) that, as a proximate result of this lack of knowledge or skill, or failure to exercise this degree of care, the patient suffered injuries which would not otherwise have been incurred. La.R.S. 9:2794.