The literature on the pathophysiology of bursitis describes inflammation as the primary cause of symptoms. Inflammatory bursitis is usually the result of repetitive injury to the bursa. In the<unk>  bursa, this generally occurs due to microtrauma to adjacent structures, particularly the supraspinatus tendon. The inflammatory process causes synovial cells to multiply, increasing collagen formation and fluid production within the bursa and reduction in the outside layer of lubrication. Less frequently observed causes of<unk>  include hemorrhagic conditions, crystal deposition and infection. Many causes have been proposed in the medical literature for<unk>  impingement syndrome. The bursa facilitates the motion of the rotator cuff beneath the arch, any disturbance of the relationship of the<unk>  structures can lead to impingement. These factors can be broadly classified as intrinsic such as tendon degeneration, rotator cuff muscle weakness and overuse. Extrinsic factors include bone spurs from the acromion or AC joint, shoulder instability and neurologic problems arising outside of the shoulder.
Subacromial bursitis
Rotator cuff tear
Ischial bursitis
Retrocalcaneal bursitis
Infrapatellar bursitis
Pes anserine bursitis
Calcific tendinitis
Olecranon bursitis