Subchondral stress fractures of the femoral head associated with military training: Clinical features and analysis

Table 1 Staging and imaging features of subchondral stress fracture of the femoral head

	Plain radiographs	Magnetic resonance images
Stage 0	No definite findings	Bony edema limited to the femoral head area
Stage I	Mild depression of articular margin (Crescent sign)	Low signal intensity lesion on T1 image and joint effusion
Stage II	Severe depression of articular margin	Subchondral fracture and a large joint effusion with edema extending to below the trochanter
Stage III	Arthritic changes (bone spurs or cysts)	Osteoarthritis with receding bone marrow edema