Figure 4.

The “dangerous zone” for screw placement with the Stoppa approach. In the figure, region A represents the “dangerous zone” for screw placement when the acetabulum was amplified for 2.95 mm, which is also defined as the absolute “dangerous zone.” Region B represents the “dangerous zone” when the acetabulum was amplified for 6 mm. The part of region B outside region A is the relative “dangerous zone” and the region outside B is the absolute “safe zone.”