[Reversed total shoulder arthroplasty in rotator cuff defect arthropathy]

In a progredient rotator cuff tear with tendon retraction, fatty infiltration and atrophy of rotator cuff muscles the humerus cannot be centered and stabilized sufficiently in the glenohumeral joint. This leads to rotator cuff defect arthropathy as an eccentric osteoarthritis with acetabularization and wear of the acromion, as well as of the glenoid.

A painful pseudoparalysis of the shoulder indicates the implantation of a reversed total shoulder arthroplasty (rTSA) to reduce pain and restore active motion. The rTSA improves the motoric function of the deltoid muscle by medialization and caudalization of the center of rotation via an optimized lever arm and is also indicated in cranio-caudally centered osteoarthritis with static posterior humeral decentration due to a bi-concavely eroded glenoid.

Currently, humeral anatomical resection with an inclination of 135° and a humeral retrotorsion of 20-40°, in rTSA in contrast to 155° inclination, has been shown to lead to better glenohumeral motion without loss of stability. Additionally, a reduced glenohumeral offset should be restored by especially bony lateral augmentation of the glenoid. In a pre-operatively positive lag sign for external rotation caused by a rupture of the infraspinatus/teres minor tendon, a lateral latissimus/teres major muscle tendon transfer in rTSA can optimize active external rotation. The tendon of the subscapularis muscle should be re-fixated in the deltopectoral approach for rTSA whenever possible for better anterior stability of the glenohumeral joint. Larger diameters of the glenospheres have been shown to have more stability and better motion. Humeral metaphyseal metal liners with corresponding polyethylene glenospheres can avoid osteolysis of the inferior scapular neck caused by polyethylene debris due to impingement of the humeral liner at the scapular neck.