Every time the upper arm is lifted overhead, a narrowing of the space between the humeral head and acromian occurs. This space, (the subacromial space) is where tendons of the rotator cuff are located, protected by the bursa. Performing sports, or everyday activities which require repetitive overhead movements, rotator cuff muscle imbalances, or irregularities in the acromian profile may all cause increased friction inside this space, which can lead to the formation of calcium deposits within the subacromial space. The tendon most frequently involved in these injuries is the supraspinatus tendon, due to its location. The end result of these kinds of injuries are feelings of weakness and pain, often most felt at night time. The lack of movement that results from these feelings of pain can in turn perpetuate the injury as the joint becomes more and more stiff through under-use. Pre-existing, but undiagnosed wear of the shoulder joint is also a concern here as it can further contribute to the pain experienced. Quick and correct diagnosis followed by an early start to rehabilitation is key here, as stopping the vicious cycle mentioned above ensures rehabilitation is faster and more effective. Adopting this approach negates the need for prolonged courses of anti-inflammatory drugs, as well as preventing secondary damage to the joint through the adoption of bad postures or movement patterns. In cases of large calcific deposits, or complete tears of the rotator cuff tendon, surgery may be required. However, rehabilitation is always necessary here to correct and prevent the underlying issues which may have led to the injury forming in the first place.