"type I: fracture inferior to the fovea capitis, a small fracture not involving the weightbearing surface"
"type II: fracture extending superior to the fovea capitis, a large fracture involving the weightbearing surface"
"type III: type I or II fracture with a fracture of the femoral neck, has an increased risk of avascular necrosis (rarest type)"
"type IV: type I or II fracture with a fracture of the acetabular wall, usually the posterior wall"