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

Figure 2 Representative radiographs and T1-weighted magnetic resonance images of subchondral stress fracture of the femoral head and osteonecrosis of the femoral head. A-F: Imaging findings in a 20-year-old male recruit with subchondral stress fracture of the femoral head (SSFFH) (A-C) and a 45-year-old military officer with osteonecrosis of the femoral head (ONFH) (D-F). A and D: Radiographs show similar articular-surface collapse in both SSFFH and ONFH; the white triangles indicate subchondral fracture; B and C: Magnetic resonance imaging (MRI) of SSFFH reveals an irregular subchondral low-signal band (white arrow) with surrounding bone marrow edema and an irregular, thickened sclerotic margin; E and F: MRI of ONFH demonstrates a smoother, serpiginous low-signal band demarcating the necrotic segment, with a subchondral fracture indicated by the white triangle. These findings illustrate the potential overlap on radiographs and the added value of MRI for differential classification.