We wish to add further proof to the existence of a type of acute bone atrophy which appears much more rapidily and is more extensive than that following disuse. In many cases of this type, there has been no inactivity. Such atrophies may occur as a complication of injuries to the ankle or knee joints, or a Colles' fracture. The results of treatment of such injuries are so uniformly good that one is likely to overlook the exceptional cases in which convalescence is prolonged, and pain and stiffness of the hand or foot with trophic changes persist for many months. Pain dominates the clinical picture, and the roentgenologic findings are very definite, and quite distinct from those of chronic bone atrophy. REVIEW OF THE LITERATURE Acute bone atrophy was first established as a definite clinical entity, in 1900, by Sudeck.1 He clearly demonstrated that there were two types of