Traditionally this has been thought to be a significant cause of post-stroke shoulder pain, although a few recent studies have failed to show a direct correlation between shoulder subluxation and pain. The exact cause of subluxation in post-stroke patients is unclear but appears to be caused by weakness of the musculature supporting the shoulder joint. The shoulder is one of the most mobile joints in the body. To provide a high level of mobility the shoulder sacrifices ligamentous stability and as a result relies on the surrounding musculature (i.e., rotator cuff muscles, latissimus dorsi, and deltoid) for much of its support. This is in contrast to other less mobile joints such as the knee and hip, which have a significant amount of support from the joint capsule and surrounding ligaments. If a stroke damages the upper motor neurons controlling muscles of the upper limb, weakness and paralysis, followed by spasticity occurs in a somewhat predictable pattern. The muscles supporting the shoulder joint, particularly the supraspinatus and posterior deltoid become flaccid and can no longer offer adequate support leading to a downward and outward movement of arm at the shoulder joint causing tension on the relatively weak joint capsule. Other factors have also been cited as contributing to subluxation such as pulling on the hemiplegic arm and improper positioning. Diagnosis can usually be made by palpation or by feeling the joint and surrounding tissues, although there is controversy as to whether or not the degree of subluxation can be measured clinically. If shoulder subluxation occurs, it can become a barrier to the rehabilitation process. Treatment involves measures to support the subluxed joint such as taping the joint, using a lapboard or armboard. A shoulder sling may be used, but is controversial and a few studies have shown no appreciable difference in range-of-motion, degree of subluxation, or pain when using a sling. A sling may also contribute to contractures and increased flexor tone if used for extended periods of time as it places the arm close to the body in adduction, internal rotation and elbow flexion. Use of a sling can also contribute to learned nonuse by preventing the functional and spontaneous use of the affected upper extremity. That said, a sling may be necessary for some therapy activities. Slings may be considered appropriate during therapy for initial transfer and gait training, but overall use should be limited. As the patient begins