Ankylosing spondylitis (AS) is a chronic inflammatory disorder of the sacroiliac (SI) joints and the axial skeleton often having a strong genetic predisposition. Ankylosing spondylitis is a disease characterized by pain and progressive stiffness. It is part of a group of rheumatic diseases medically known as spondyloarthropathies which actually involves the vertebral joints and shares the human antigen HLA-B27.
Supraspinatus tendonitis is a common injury in many sports that include aggressive overhead movements. The supraspinatus is a muscle located on the top of the shoulder blade or scapula, which mechanically connects the upper arm (humerus) to the scapula. Inadequate dynamic muscle balance, overuse, and poor range of motion prior to physical activities are all causes of supraspinatus tendonitis. Sports commonly associated with supraspinatus tendonitis are weight lifting, swimming, baseball, tennis, and racquetball. Any rapid overhead motion, and especially those where resistance against this movement is involved, are activities which put the supraspinatus at risk of injury.