Both mechanical factors (left) and nutritional factors (right) contribute to joint destruction in rotator cuff-tear arthropathy. (Reproduced with modification from: Neer CS 2nd, Craig EV, Fukuda H. Cuff-tear arthropathy. J Bone Joint Surg Am. 1983;65:1232-44.)

Clinical picture of the left shoulder in a patient with rotator cuff-tear arthropathy, demonstrating anterior (left arrow) and superior (right arrow) escape of the humeral head resulting from loss of the subscapularis with a grossly deficient rotator cuff.

Fig. 3-A Anteroposterior radiograph of the right shoulder after a glenohumeral arthrodesis. (Reprinted from: Scalise JJ, Iannotti JP. Glenohumeral arthrodesis after failed prosthetic shoulder arthroplasty. Surgical technique. J Bone Joint Surg Am. 2009;91 Suppl 2[Pt 1]:30-7.). Fig. 3-B Anteroposterior radiograph of the right shoulder after a constrained total shoulder arthroplasty. (Reprinted from: Post M, Haskell SS, Jablon M. Total shoulder replacement with a constrained prosthesis. J Bone Joint Surg Am. 1980;62:327-35.)

Axillary view radiograph of the right shoulder, demonstrating radiolucencies surrounding the glenoid component (arrows).

Grammont's original reverse total shoulder arthroplasty. (Reprinted, with permission from Elsevier, from: Boileau P, Watkinson DJ, Hatzidakis AM, Balg F. Grammont reverse prosthesis: design, rationale, and biomechanics. J Shoulder Elbow Surg. 2005;14[1 Suppl S]:147S-61S.)

Fig. 6-A and 6-B Diagrams demonstrating an earlier reverse total shoulder prosthesis design, with a small glenosphere component and a lateralized center of rotation (Fig. 6-A), versus the modern design, with a large glenosphere, a nonanatomic valgus angle of the humeral implant, and medial and distal positioning of the center of rotation (Fig. 6-B). (Reprinted, with permission from Elsevier, from: Gartsman GM, Edwards TB, editors. Shoulder arthroplasty. Philadelphia: Saunders; 2008.)

A: The seven segments of the deltoid muscle, according to Kapandji⁵⁵. B: In a normal shoulder, only the middle deltoid segment (III) and part of the anterior deltoid segment (II) can participate in active elevation. C: After implantation of a reverse prosthesis, the medialization of the center of rotation recruits more of the deltoid fibers (segments I and IV) for active elevation. (Reprinted, with permission from Elsevier, from: Boileau P, Watkinson DJ, Hatzidakis AM, Balg F. Grammont reverse prosthesis: design, rationale, and biomechanics. J Shoulder Elbow Surg. 2005;14[1 Suppl S]:147S-61S.)

Intraoperative photographs of the glenoid baseplate being inserted via a deltopectoral approach (Fig. 8-A) and the final positioning of the reverse total shoulder prosthesis (Fig. 8-B).

Quadrants and scoring system utilized for grading each damage mode. (Reprinted, with permission from Elsevier, from: Nho SJ, Nam D, Ala OL, Craig EV, Warren RF, Wright TM. Observations on retrieved glenoid components from total shoulder arthroplasty. J Shoulder Elbow Surg. 2009;18:371-8.)

Photographs of retrieved humeral implants demonstrating inferior-quadrant abrasion (a, arrow) and diffuse third-body debris (b). (Reprinted, with permission from Elsevier, from: Nam D, Kepler CK, Nho SJ, Craig EV, Warren RF, Wright TM. Observations on retrieved humeral polyethylene components from reverse total shoulder arthroplasty. J Shoulder Elbow Surg. In press, 2010.)