The neutral triangle is seen radiologically in-
Neutral triangle of the calcaneum

Within the trabeculae of calcaneus lies the neutral triangle, an area directly below the distal edge of a posterior facet.
The base of the triangle is the weakest, most vulnerable portion of the calcaneum.
Axial impaction of the talus into the calcaneum results in a vertical fracture through the neutral triangle, and it represents the primary fracture line.
Neck femur
Proximal humerus
Calcaneum
Talus