Magnetic resonance imaging (MRI) of the hip. Small to moderate articular effusion in the right hip joint, with synovitis and marked dysmorphia of the femoral head with flattening of its superior slope (thin red arrow), and peripheral, subcortical edema of the femoral head involving almost all of the articular surface, delimited by a well-defined serpiginous line (thick red arrow). In the context of the given patient, these findings should represent avascular necrosis of the femoral head, probably post-traumatic, in stage IV