Methods, systems, and apparatus regarding a Rotation & Abduction Device (“RAD”) for shoulder immobilization in treating shoulder instability, wherein the ability to maintain particular degrees of shoulder rotation and abduction is desired or necessary. An exemplary RAD shoulder immobilization system may include: a frame a harness connected to the frame and including a waist support and a neck/shoulder strap a sling connected to the frame and the harness and a lining covering parts of the frame, the harness, and/or the sling. A method of treating a shoulder disorder may include: providing a shoulder immobilization system capable of shoulder rotation positioning adjustment and capable of shoulder abduction-adduction positioning adjustment putting the shoulder immobilization system on a wearer adjusting the shoulder immobilization system for shoulder rotation positioning and adjusting the shoulder immobilization system for shoulder abduction-adduction positioning. Numerous other aspects are provided.
