Ankylosing spondylitis (AS) is a chronic inflammatory disorder
mainly involving the sacroiliac joints and spine, although
peripheral joints may also be involved. Inflammation of
ligament or tendon insertion at the bone (enthesopathy) is
also a characteristic finding. The disease can be accompanied
by extraskeletal manifestations, such as acute anterior uveitis,
aortic incompetence, cardiac conduction defects, fibrosis of
the upper lobes of the lungs, neurological involvement, or
renal amyloidosis [1]. In a recent report, patients with ASwere
at increased risk for cardiac morbidity including coronary
artery disease [2]. The prevalence of AS is 0.15% to 0.86% [1].
The main biomechanical problems in patients with AS
include limitations in spinal and peripheral joint mobility,
restriction of chest expansion [3], reduction of vital capacity