by Naoko Mizuno, Patrick J. Denard, Patric Raiss, and Gilles Walch Reverse Total Shoulder Arthroplasty for Primary Glenohumeral Osteoarthritis in Patients with a Biconcave Glenoid by Naoko Mizuno, Patrick J. Denard, Patric Raiss, and Gilles Walch J Bone Joint Surg Am Volume 95(14):1297-1304 July 17, 2013 ©2013 by The Journal of Bone and Joint Surgery, Inc.

The retroversion of a biconcave glenoid can be measured three different ways relative to the Friedman line (ED). The retroversion of a biconcave glenoid can be measured three different ways relative to the Friedman line (ED). Line AB represents the native glenoid or paleoglenoid; the retroversion of the paleoglenoid (RV1 angle) is the angle between line AB and a line perpendicular to the Friedman line. Line AC represents the intermediate glenoid; the retroversion of the intermediate glenoid (RV2 angle) is the angle between line AC and a line perpendicular to the Friedman line. Line BC represents the posterior eroded surface or neoglenoid; the retroversion of the neoglenoid (RV3 angle) is the angle between line BC and a line perpendicular to the Friedman line. Naoko Mizuno et al. J Bone Joint Surg Am 2013;95:1297-1304 ©2013 by The Journal of Bone and Joint Surgery, Inc.

Humeral head subluxation can be assessed with regard to the scapular axis. Humeral head subluxation can be assessed with regard to the scapular axis. A line is drawn from the medial tip of the scapula through the center of the glenoid, also called the Friedman line (line ED). Another line is drawn perpendicular to the Friedman line such that it passes through the widest portion of the humeral head. Humeral head subluxation is then estimated at the percentage of the humeral head that lies posterior to the Friedman line. In this example, the subluxation (HI/GI) is 80.2%. Note that the center of the humeral head (J) is not required in this measurement. Naoko Mizuno et al. J Bone Joint Surg Am 2013;95:1297-1304 ©2013 by The Journal of Bone and Joint Surgery, Inc.

Fig. 2-A Radiograph showing primary glenohumeral arthritis in a seventy-six-year-old woman. Fig. 2-A Radiograph showing primary glenohumeral arthritis in a seventy-six-year-old woman. Fig. 2-B Preoperative axial CT scan showing severe posterior glenoid erosion and posterior subluxation of the humeral head. Fig. 2-C Radiograph made after reconstruction of the glenoid with use of a structural iliac crest autograft. The central peg of the glenoid baseplate was not anchored in the native glenoid. Fig. 2-D Radiograph made four months postoperatively, showing migration of the glenoid component. Fig. 2-E Radiograph made after revision to a hemiarthroplasty. Naoko Mizuno et al. J Bone Joint Surg Am 2013;95:1297-1304 ©2013 by The Journal of Bone and Joint Surgery, Inc.

Fig. 3-A Axial CT image of the shoulder of a seventy-two-year-old man with primary glenohumeral osteoarthritis and a biconcave glenoid with severe posterior erosion. Fig. 3-A Axial CT image of the shoulder of a seventy-two-year-old man with primary glenohumeral osteoarthritis and a biconcave glenoid with severe posterior erosion. Fig. 3-B Intermediate retroversion (RV) was 50°, and humeral head subluxation was 95°. Fig. 3-C Reverse shoulder arthroplasty was performed with iliac crest bone graft and an extra-long 25-mm central peg that allowed the baseplate to be anchored in the native glenoid. Fig. 3-D Radiograph, made four years postoperatively, showing healing of the graft. Partial inferior osteolysis of the graft was interpreted as Grade-2 notching. Naoko Mizuno et al. J Bone Joint Surg Am 2013;95:1297-1304 ©2013 by The Journal of Bone and Joint Surgery, Inc.