Chronic posterior subluxation and dislocation of the radial head. The clinical and radiographic features of chronic posterior subluxation or dislocation of the radial head were studied in thirty-four elbows of twenty-seven patients. Three characteristic radiographic types were noted: Type I, subluxation; Type II, posterior dislocation with minimum displacement; and Type III, posterior dislocation with substantial proximal migration of the radius. Follow-up of eighteen patients (twenty-one elbows) revealed that posterior displacement did not usually cause serious functional impairment except for loss of rotation of the forearm. The least common presentation, Type-I subluxation, caused pain and clicking and was associated with late degenerative arthritis. Cosmetic deformity due to prominence of the radial head was also a cosmetic problem, particularly with Type-III dislocation. 