The authors have demonstrated three-dimensional computed tomography imaging of soft tissues, such as the labrum and the anterior inferior glenohumeral ligament (AIGHL). We have called this imaging method 3DCT shoulder virtual arthroscopy (3DCTSVA). The aim of this study was to investigate whether 3DCTSVA can be used to visualize the internal architecture of anterior shoulder instability in comparison to surgical arthroscopy. This study involved twentytwo patients. There were 17 males and 5

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... es, with a mean age of 23.8 years. All patients had suspected anterior shoulder instability, as determined by patient history and physical examination, and underwent 3DCTSVA before arthroscopy. Each of the joints was injected with 20 cc air, and was then scanned immediately with a helical CT (Toshiba helical CT Aquilion slice thickness: 1 mm, slice pitch: 0.5 mm, WL: 40, WW: 250). The data obtained was entered into a workstation, and commercially available software was used to create a three-dimensional simulation of a lesion in the shoulder. Reconstruction images were then obtained. The findings of 3DCTSVA were compared with arthroscopy findings. In all 22 cases, Bankart lesion was correctly identified on 3DCTSVA. In 20 of 22 cases, AIGHL was correctly identified. In 20 of 22 cases, middle glenohumeral ligament (MGHL) was correctly identified. The sensitivity, specificity and accuracy predictive values for Bankart lesion were 100%, 100% and 100%, respectively. The sensitivity, specificity and accuracy for AIGHL were 100%, 77% and 90%. The sensitivity, specificity and accuracy for MGHL were 100%, 84% and 90%, respectively. 3DCTSVA offers fine images of the anterior labrum capsule complex of the shoulder with Bankart lesion, AIGHL and MGHL. The use of 3DCTSVA will enable us to determine the state of an anterior lesion of the shoulder before actually performing arthroscopy. 3DCTSVA is a promising method for detecting the sources of derangement of the shoulder.