In Situ Assembly of a Modular Noncemented Total Shoulder Prosthesis for the Reconstruction of Complex Joint Pathology

Exact restoration of the glenohumeral joint, especially in the case of complex pathologies, due to high prosthesis modularity and in situ assembly; later conversion to inverse design with same shaft possible. Primary shoulder osteoarthritis, secondary joint destruction after previous fracture or its treatment, humeral head necrosis, or inflammatory processes, revisions of defect situations such as hemiprostheses. General contraindications of total shoulder arthroplasty, additionally, functional loss of the rotator cuff, advanced osteoporosis, narrow medullary canal, e.g., in patients with juvenile rheumatoid arthritis. After deltopectoral approach free resection of the humeral head along landmarks, stepwise rasping of the humeral medullary canal, insertion of the rectangled stem, realignment of humeral height with the body, realignment of inclination and possible retroversion with the inclination set. The asymmetric head ensures exact restoration of the joint center. Implantation of the cemented glenoid, test of range of motion and soft-tissue tension, and exchange of components in situ, if necessary. A prospective evaluation of the first 146 consecutive patients with 1-year follow-up revealed significant improvements of about 151% regarding pain and of about 98% in function without significant differences between different indications. Four shaft fissures were observed and treated with intraoperative cerclages during the learning period. No further fissures were noted after adaptation of the surgical procedure and subsequent guidelines. One traumatic and one atraumatic head rotation were observed but should be prevented with a new torque wrench. Similar functional results can be achieved even in complex shoulder pathologies due to the high modularity of the prosthesis.