Complications of Reverse Total Shoulder Arthroplasty: A Computational Modelling Perspective

Reverse total shoulder arthroplasty (RTSA) is an established treatment for elderly patients with irreparable rotator cuff tears, complex proximal humerus fractures, and revision arthroplasty; however, with the increasing indications for RTSA over the last decade and younger implant recipients, post-operative complications have become more frequent, which has driven advances in computational modeling and simulation of reverse shoulder biomechanics. The objective of this study was to provide a review of previously published studies that employed computational modeling to investigate complications associated with RTSA. Models and applications were reviewed and categorized into four possible complications that included scapular notching, component loosening, glenohumeral joint instability, and acromial and scapular spine fracture, all of which remain a common cause of significant functional impairment and revision surgery. The computational shoulder modeling studies reviewed were primarily used to investigate the effects of implant design, intraoperative component placement, and surgical technique on postoperative shoulder biomechanics after RTSA, with the findings ultimately used to elucidate and mitigate complications. The most significant challenge associated with the development of computational models is in the encapsulation of patient-specific anatomy and surgical planning. The findings of this review provide a basis for future direction in computational modeling of the reverse shoulder.

Multimodality imaging in shoulder arthroplasties Part 1: Biomechanics, indications, preoperative imaging, and types of arthroplasties – A pictorial review

Shoulder biomechanics, shoulder arthroplasty indications and types and appropriate pre-operative imaging are discussed in part one of this two-part pictorial review. Shoulder biomechanics in severe osteoarthritis and following reverse shoulder arthroplasty are represented graphically, with discussion on the principles of reverse shoulder arthroplasty. Case examples are utilized to demonstrate the main indications for shoulder arthroplasty. The decision of whether to proceed with arthroplasty and the arthroplasty type is heavily influenced by the pre-operative imaging. Factors for type of arthroplasty include arthroplasty indication, the integrity of the deltoid and rotator cuff musculature, and the amount of glenoid and humeral head bone stock. The key findings to look for and comment on across a range of imaging modalities are reviewed, using multiple cases including plain radiography, CT, ultrasound, and MRI. Examples of arthroplasty options are provided including humeral head resurfacing arthroplasty, hemiarthroplasty, anatomical total shoulder arthroplasty, and reverse total shoulder arthroplasty. A good understanding of the above principles is crucial for the radiologist to interpret pre-operative imaging correctly and aid in surgical planning.