Abstract: Objectives: Dislocations and periarticular fractures of the acromioclavicular joint are common injuries of the shoulder girdle. When surgical intervention is indicated, subacromial support is one option to restore the alignment between scapula and the distal/lateral clavicle. Devices used for subacromial support rely on a form of subacromial 'hook'. The shape, inclination and orientation of which is often mismatched to the anatomy of the inferior surface of the acromion, which may lead to painful acromial osteolysis and rotator cuff abrasion causing impingement. The primary goal of this study was to characterize the geometrical parameters of the acromion and distal clavicle, and their orientation at the acromioclavicular joint. Methods: Computed tomography scans of 120 shoulders were converted into digital three-dimensional models. Measurements of the acromion inclination and acromion width relative to the torsional angle as well as the clavicle depth were taken. A numerical optimization of the anatomical parameters (including torsional and inclination angles, height and width) was performed to find the combination of those parameters with the lowest interpatient variability. Results: The mean clavicle depth was found to be 11.1 mm. The mean acromion width was 27 mm. The combination of torsional and inclination angles with lowest interpatient variability was found at 80° and 16°, respectively. Conclusion: There is a high interpatient variability in the morphology of the inferior surface of the acromion. Subacromial support using a 'hook' can be optimized for contact surface area, which should lead to fewer complications after the restoration of acromioclavicular orientation using acromial support strategies

Abstract: Hardware prominence remains a clinical challenge in focus for implant design in subcutaneous plate applications. Existing evaluation of hardware prominence relies on plate-to-bone distance at a single point or on average. A reproducible measure for plate prominence remains undefined. This study mathematically defines the plate prominence linked to the cross-sectional area change due to the plate presence on the bone. Two anatomical plate designs were fitted to 100 clavicles, and afterwards plate prominence parameters were evaluated and compared. This methodology enables the quantification of hardware prominence for different plate designs to inform the development of implants targeting low prominence