Radiographic Analysis of Grammont-Style and Lateralized Reverse Shoulder Arthroplasty in Gleno-Humeral Osteoarthritis

Abstract

Reverse shoulder arthroplasty (RSA) has transformed the management of shoulder pathologies, including cuff tear arthropathy and osteoarthritis. The innovative design principles of RSA, such as the medialization and inferiorization of the joint center of rotation, distalization of the humerus, and a semi-constrained construct, enable effective deltoid compensation for rotator cuff deficiency. The Grammont-style RSA demonstrated excellent clinical outcomes. However, complications like instability and scapular notching prompted the exploration of lateralized designs. The radiographic evaluation of RSA is paramount for understanding the biomechanics of the implant and to foresee possible complications. Radiographic assessments encompass glenoid and humeral component positions, identifying features like scapular notching, radiolucent lines, heterotopic ossifications, bone adaptations, and humeral lengthening. Lateralized designs alter muscle moment arms and improve deltoid efficiency, influencing abduction and adduction mechanics. Despite the reduction in scapular notching, lateralized RSA introduces new challenges, such as increased risk of scapular spine and acromial fractures. Understanding the radiographic features and biomechanics of lateralized RSA is crucial for optimizing patient outcomes and mitigating potential complications.