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 < 0.05). Using the software to measure the mid-lateral distance, as well as in the measurement with the caliper, the model type influenced the measurements for each of the observers, rendering the method invalid (p < 0.05).

There was no reproducibility and repeatability for Hill-Sachs lesion measurement between plaster models and software models.