In revision shoulder arthroplasty, proximal humerus loss is common. Bone loss may be due to component loosening with resulting osteolysis, infection or preoperative and postoperative fracture. A careful preoperative assessment can guide surgical planning. The quantity and quality along the diaphysis, and metaphysis of the humerus, as well as the condition of important soft tissues, such as the rotator-cuff, the deltoid, and the pectoralis minor, are of particular importance.
Deficient humeral bones can cause instability in the joint as well as the fixation of the revision implants.
1. Joint Instability
The stability of a reverse total shoulder is dependent on concavity compressio: the compression by the deltoid or other scapulohumeral musculature of the glenosphere in the concavity humeral lining.
Inadequate restoration of humeral size and/or soft tissues attachments to the proximal part of the humerus can cause post-revision glenohumeral instabilities of the reversed total shoulder. Loss of length in the humerus reduces tension in the deltoid. This decreases its capacity to provide the compression force that stabilizes a joint ….