Figure 1. Estimation of glenoid axis and height according to the method of Barth⁽¹³⁾. Two circumferences are traced: one lower, taking the posteroinferior glenoid border as reference, and one higher than the other and tangential to the glenoid borders. The line joining the centre of both circumferences is taken to represent the axis of the glenoid cavity. Over this, the height corresponding to half of the glenoid cavity and to 25% is established.