Pain and Stiffness. Although spondylitis simply means an inflammation of the spine, I believe that you are referring to ankylosing spondylitis. The usual symptoms begin with pain and stiffness of the lower back and the buttock areas. The symptoms are usually worse in the morning and during the night. There may an associated mild fever, loss of appetite, fatigue, uveitis, and mild to moderate anemia.
Backache. Morning stiffness back pain with extension sometimes as spurs grow and inflammation increases nerve irritation from stenosis will cause leg forward curving with ankylosing.
Varies. Spondylitis simply refers to degeneration seen on an imaging study of the spine, either plain xray, mri, or ct. Many times such degeneration is asymptomatic. Sometimes the degeneration is severe enough that spinal instability can result, or even compression of the neural elements. The devil is really in the details with such a general term.
See details. The major symptom is pain. Early in the disease course the pain is worse at rest and improved with activity. With time, unless this is aggressively treated, calcifications of the spinal ligaments will lead to irreversible loss of motion. Spondylitis can also cause cardiac, pulmonary and peripheral arthritic issues.