The specimens were fresh-frozen and stored at a temperature of − 20 °C until experiments. The specimens were thawed at room temperature for 24 h prior to the procedure. All procedures were performed in the lateral decubitus position, with the arm at 45° of abduction. The posterior portal for the scope was created 1.0 cm lateral to the standard portal, so 1 cm medial and 5 mm inferior to the acromial edge. This portal was used to insert the posterior guide in a correct position on the glenoid, thus avoiding to do an accessory posterior portal.