Joint stiffness is another presentation usually associated with the other cardinal features of pain and swelling. Morning stiffness and stiffness after periods of inactivity are characteristic of rheumatoid arthritis but may occur with other forms of arthritis. Less than 10 minutes of stiffness is common in osteoarthritis compared with more than 30 minutes in inflammatory arthritis. Sacroiliac stiffness is a particular feature of ankylosing spondylitis. Locking of a joint is a sudden inability to complete a movement, such as extension at the knee caused by a mechanical block such as a foreign body in the joint or a torn meniscus.