Establishment of a True En Face View in the Evaluation of Glenoid Morphology for Treatment of Traumatic Anterior Shoulder Instability

Purpose: To develop an accurate and reproducible method for establishment of a true en face view of the glenoid with a traumatic bone defect.

Methods: A total of 50 sets of computed tomography images of the glenoid were used for 3-dimensional reconstruction. Both a quantitative definition and a practical method were designed for creation of the true en face view of the glenoid with a traumatic bone defect. The accuracy and reliability of the quantitative definition and the practical method were evaluated by calculating the maximal projection area and the simulated bone defect size.

Results: The glenoid surface could be fit with a sphere with a radius of 26.11 ± 2.15 mm (P < .001, R² = 0.98). The true en face view could be established with the quantitative definition, which resulted in the maximal projection area, whereas any tilt would lead to decreased values (P < .05). To establish the true en face view on the glenoid with a traumatic bone defect, a vector from the center of the best-fit sphere of the glenoid surface to the middle point of an arc connecting the supraglenoid and infraglenoid tubercles was generated, which served as a perpendicular for glenoid reorientation. Cases off the true en face view would result in less accurate estimation of the bone defect size (P < .05).

Conclusions: This study provided a quantitative definition and a practical method for generation of the true en face view in the presence of a traumatic bone defect based on the best-fit sphere of the glenoid surface as well as the anatomic landmark of the supraglenoid and infraglenoid tubercles. This study may improve the reliability of the quantification of traumatic bone defects of the glenoid.

Clinical relevance: The practical method for establishment of the true en face view of the glenoid would be useful in decision making for the treatment of traumatic anterior shoulder instability.