Hill–Sachs lesion measurement with tridimensional models in anterior shoulder instability

To evaluate the reproducibility and repeatability of Hill–Sachs lesion measurement from computed tomography images, with computer software and tridimensional prototype. Three-dimensional models were made from computed tomography images from 14 patients with anterior shoulder instability, using InVesalius 3.0® software. Hill–Sachs lesions were measured with Rhinocerus 5.0® software with pre-determined position. Mid-lateral distance, perpendicular to humeral shaft, cranial-caudal distance, parallel to humeral shaft, and the longitudinal distance of the lesion were measured. Using the Printer-ZP 310 three-dimensional printer, plaster models were made. To measure the Hill–Sachs lesion, a calibrated universal digital caliper was used in the same way as the software. There was intra-observer and inter-observer variability for measurement of the same model. Observers did not perform the measurements in a similar way, showing difficulty to use the method (p