A new and/or novel image analysis technique for quantitative assessment of motion-based testing for injury in a patient using universally available and affordable devices and techniques is provided and disclosed. A video of a test being performed can be processed to track the motion of markers and/or bodily landmarks in two or more dimensions to quantitatively describe motion, thereby removing the subjective aspects typically associated with motion-based testing. In an example, the pivot shift test is a commonly used test for evaluating rotational instability of the anterior cruciate ligament (ACL)-deficient knee. The pivot shift test's subjective grading scale can be quantified and refined using image analysis techniques.