From the case:
Gartland classification of supracondylar fractures

Gartland Classification of Supracondylar Fractures (including the widely accepted Type IV)
Case Discussion
- Type I: non-displaced or minimally displaced (<2 mm) supracondylar fracture
- Type II: displaced (>2 mm) supracondylar fracture with a intact, yet hinged, posterior cortex
- Type III: displaced supracondylar fracture with no meaningful cortical contact
- Type IV: displaced; multidirectional instability due to an incompetent periosteal hinge, being unstable in both flexion and extension.