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.
Spondylolysis is a condition created when a localized fracture of the bony arch, referred to as the pars interarticularis. This injury is most commonly located in the lumbar spine. This stress fracture is usually do to excessive force or repeated strain. Learn how to fix that "damn back" problem.