IGES File - difficulty placing Points

I have a CT scan of a knee, and converted it to an IGES file. The goal is to select landmark points on the knee as seen in the attached image. Unfortunately, when I try to create a point, Pro/E will only allow me to select 1 edge (red line) of a 'rectangular' surface on the IGES knee file. I want to create a point inside this rectangular surface, but I have not been able to figure out how to do this. Please let me know if you can help. Thanks.