Types of adjustable plaster casts which have been used advantageously for the treatment of flexion deformities of knees and elbows in patients with rheumatoid arthritis and other joint diseases have been described. Such casts remain effective for many weeks, and represent a great saving of time and labor as compared with the practice of making an entirely new cast every week or two, as the deformity of a joint improves. Furthermore, in comparison with other varieties of casts and traction, it has become apparent that these hinged casts, kept well adjusted to the joints and without strain at all times, provide the most effective correction of deformities. The importance of daily exercise of the joints without weight-bearing cannot be too strongly stressed. Althotigh adjustable casts exhibit their chief value for knees and elbows, they are useful occasionally at other sites.