Three-Dimensional Mapping of Scapular Body, Neck, and Glenoid Fractures

Objectives: The purpose of this study was to report patterns of scapular fractures and define them with a contemporary methodology. Methods: Design: Retrospective study, 2015 – 2021 Setting: Single, Academic, Level 1 Trauma Center Patient Selection Criteria: Consecutive patients ≥ 18 years, presenting with unilateral scapula fracture, with thin-slice (≤ 0.5 mm) bilateral CT scans of the entirety of both the injured and uninjured scapulae Outcome Measures and Comparisons: Thin-slice (0.5 mm) computed tomography (CT) scans of injured and normal scapulae were obtained to create three-dimensional (3D) virtual models. 3D modeling software (Stryker Orthopedics Modeling and Analytics, Stryker Trauma GmbH, Kiel, Germany aka SOMA) was used to create a 3D map of fracture location and frequency. Fracture zones were delineated using anatomic landmarks to characterize fracture patterns. Results: 87 patients were identified with 75 (86%) extra-articular and 12 (14%) intra-articular fractures. The dominant fracture pattern emanated from the superior lateral border (Zone E) to an area inferior to the spinomedial angle (Zone B) and was present in 80% of extra-articular fractures. A second-most common fracture line propagated from the Primary (most-common) Line towards the inferior medial scapular border with a frequency of 36%. Bare zones (with one or no fractures present) were identified in four unique areas. Furthermore, intra-articular fractures were found to be heterogenous. Conclusions: The 3D fracture map created in this study confirmed that extra-articular scapular fractures occur in certain patterns with a relatively high frequency. Results provide greater insight into scapular fracture locations and may help to study prognosis of injury and improve treatment strategy including operative approaches and surgical tactics.