Subluxation in the Arthritic Shoulder.

Abstract

The term "subluxation" means partial separation of the joint surfaces. In the arthritic shoulder, "arthritic glenohumeral subluxation" refers to displacement of the humeral head on the surface of the glenoid. The degree of arthritic glenohumeral subluxation can be measured using radiography with standardized axillary views or computed tomography (CT). Shoulders with a type-B1 or B2 glenoid may show more posterior subluxation on an axillary radiograph that is made with the arm in an elevated position than on a CT scan that is made with the arm at the side. The degree of arthritic glenohumeral subluxation is not closely related to glenoid retroversion. The position of the humeral head with respect to the plane of the scapula is related to glenoid retroversion and is not a measure of glenohumeral subluxation. Studies measuring glenohumeral subluxation before and after arthroplasty should clarify its importance to the clinical outcomes of shoulder reconstruction.