The pioneering medical drama helped launch the career of screen legend Denzel Washington. The unusually stacked cast of 'St. Elsewhere,' circa 1985Credit: GettyIt may not have been a ratings behemoth, but St. Elsewhere has stood the test of time. Decades after its six-season run came to an end, it remains one of the most influential and enduring dramas, medical or otherwise, in TV history.The series, created by Joshua Brand and John Falsey, foll…