“Defendants acknowledged at oral argument that the record does not tell us whether the alleged hand-soaking occurred before or after the sutures were removed. But if Butts-Franklin had soaked her hand after the sutures were removed, it ‘c[ould not] be the basis for a mitigation of damages instruction’ because she ‘did not act contrary to the advice given,'” Justice Stuart A. Raphael wrote on behalf of the unanimous appellate panel.