A lady with painful stiff shoulder secondary to rheumatoid arthritis was scheduled for should replacement surgery.

The CT scan showed extensive erosion of the glenoid. The bone model confirmed the erosion and and a mock surgery on the model revealed the following :-

Figure 1 : If one were to place the glenoid component there could be fracture of the central wall	Figure 2 : There was a possibility of inserting the glenoid component in excessive retro version because of the posterior slope.

Hence, instead of total shoulder replacement, only hemi-arthoplasty (partial replacement) would give long lasting result.

The model helped in avoiding the complication of fracture of the glenoid / improper version of the glenoid component on the table both of which would have resulted in early failure.