Basis of the modern shoulder implants is the Neer II-system, a non constrained total
shoulder prosthesis with conforming radii of curvature and improved protection against dislocation. The second generation of
shoulder prosthesis is based on the geometric shaft design of the Neer II
prosthesis and offers not only a variety of modular head- and shaft-sizes but also through different radii a physiologic rotation-translation-mechanism. The third generation of
humeral head prosthesis carries the concept of an anatomic reconstruction one step further and enables the surgeon to adjust the inclination and the eccentric offset of the humeral head to restore the centre of rotation. The latest development in shoulder
arthroplasty are
humeral head prosthesis with a fully variable 3-dimensional modularity to independently adjust the prosthetic head position regardless of the individual shaft geometry. This achieves a 3-dimensional adaptability of the prosthetic head about the stem axis in the coronary and in the sagittal plane. Besides of the humeral shaft
prosthesis an alternative concept of shoulder joint replacement is established - the replacement of the humeral head articular surface. A hemispheric surface
prosthesis - cup
arthroplasty - is cemented onto the residual humeral head, which eliminates the obligatory humeral head resection and the reaming of the medullary canal. Bipolar
shoulder prosthesis are humeral shaft
prosthesis with a bi-rotational head system. Their indication is limited to pre-existing lesions of the rotator cuff and/or the glenoid surface. The inverse total
shoulder prosthesis reverses the articular surface morphology of the humeral head and the glenoid. The hemispheric glenoid component serves as the centre of rotation for the concave epiphyseal proximal humerus component. This implant is especially used in cases of massive rotator cuff deficiencies. The role of
shoulder prosthesis in treating acute
humeral head fractures needs special consideration. A fracture
prosthesis has to restore the exact length of the humerus, the centre of rotation, and the anatomical retroversion. Positioning of the tubercula and their adequate osteosynthesis is most critical and fundamental to ensure a correct healing process. A failed consolidation of the tubercula does not lead to a satisfying result. The shoulder joint replacement can be sufficiently fixated in cemented, cementless or hybrid techniques. Today several component design variations of cemented glenoid implants exist. Their main distinction is the fixation system which can be divided into two main groups - the keel - and the peg-shaped glenoid components. The peg-shaped anchorage system shall guarantee a greater stability against shear-forces. Cementless glenoid components consist of a
polyethylene inlay and a surface treated
metal-back with an integrated fixation system. These fixation systems are object of intensive biomechanical research and range from conventional screw fixation to specialised cone systems and self-cutting cage-screw-systems. The critical area of cementless glenoid components is the transition zone of the PE-
inlay and the
metal-back because of high force development. The question of implanting a hemi- or total
shoulder prosthesis is answered by the morphologic changes of the glenoid articular surface, which includes the size of the subchondral defect and the underlying etiology of the shoulder joint disease, and the age of the patient. Preoperative planning must consist of an adequate radiologic work-up - X-ray, CT or MRI - to accurately assess the glenoid morphology. G. Walch categorised the different glenoid lesions and developed a very important classification of possible glenoid deformations. To compare and evaluate the operative results one must consider the different
shoulder prosthesis and the discrepancies between a hemi- and a total
shoulder prosthetic replacement. Looking at the loosening and survival rate of the implant the results are