Staging of Osteoarthritis of the Carpometacarpal Joint of the Thumb Using Three-Dimensional Computed Tomography

Abstract

To develop a new staging system for osteoarthritis (OA) of the carpometacarpal joint of the thumb (CMJT), we obtained three-dimensional computed tomographic images of 19 thumbs with OA of the CMJT. These cases were divided into three groups at the early, progressive, and terminal stages. In the early stage, the trapezium (Tz) and the first metacarpal bone retained their normal anatomical relationship and were in contact with the subchondral bones. In the progressive stage, the surface of the Tz became grooved, and the first metacarpal bone (1^st MC) was subdislocated dorsally along the groove. In the terminal stage, the 1^st MC had sunk into the Tz and become fixed in a flexed and pronated position.
One of the 19 thumbs was at the early stage, nine were at the progressive stage, and nine were at the terminal stage. With this staging system, the features of the stages clearly differ from one another, making it easier to choose the best clinical treatment.