Oregon Shoulder Range of Motion (OS ROM) is a clinical assessment tool used to measure shoulder joint mobility. It is a standardized assessment process that allows clinicians to measure the range of motion of a patient’s shoulder joint in all three planes of motion: flexion, abduction, and external rotation. OS ROM is typically used to evaluate the progress of shoulder rehabilitation after surgery, injury, or other shoulder condition. It is also used to compare the range of motion in the shoulder to the normal range of motion. There are four types of OS ROM assessments: Active, Passive, Active-Assisted, and End-Range. Active OS ROM involves the patient actively moving their shoulder joint through its range of motion without any assistance from the clinician. Passive OS ROM involves the clinician moving the shoulder joint through its range of motion, with the patient in a relaxed position. Active-Assisted OS ROM involves the patient and clinician working together to move the shoulder joint through its range of motion. End-Range OS ROM involves the patient actively stretching the shoulder joint to its maximum range of motion.