Chronic loss of joint motion of the carpometacarpal joint of the thumb due to structural changes in non-bony tissue. This joint is formed by the first metacarpal and the trapezial bone and is also called Articulatio carpometacarpalis pollicis, carpometacarpal articulation of thumb, carpometacarpal joint of thumb or first carpometacarpal articulation. Seldom referred to as thumb saddle joint. [from
HPO]