Mismatch. The reamed glenoid concavity diameter of curvature is 2 mm greater than that of the humeral head prosthesis, usually 58 and 56 mm, respectively. (Reproduced, with permission of Elsevier, from: Matsen FA 3rd, Clinton J, Rockwood CA Jr, Wirth MA Lippitt MA. Glenohumeral arthritis and its management. In: Rockwood CA Jr; Matsen FA 3rd; Wirth MA; Lippitt SB, editors. The shoulder. 4th ed. Philadelphia: Saunders; 2009.)