Abstract: A device capable of determining the condition of knee ligaments in a patient, particularly the posterior cruciate ligament (PCL), has a foot receptacle rotatable about an axis of rotation of the patient's tibia, and the receptacle is operatively linked to a device configured to apply a measured force to rotate the tibia about its axis, and further has a means for measuring the angle of rotation of the tibia in response to that force. By measuring the angle of rotation relative to the force of rotation, a diagnosis can be made of the health of the knee, particularly the PCL.