Various embodiments, aspects and features of the present solution encompass a manually adjustable patient positioning device that is configured to reside on an operating table and outside the sterile field of a surgical environment. A carriage assembly rides along a pair of parallel guide rails and supports a cushioning device. A patient's foot, for example, may be placed on the cushioning device such that repositioning of the carriage assembly along the guide rails causes manipulation of the position and degree of articulation for the patient's knee during an orthopedic surgery.