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. 2015 Jun 19;35(5):478–484. doi: 10.1097/BPO.0000000000000318

FIGURE 1.

FIGURE 1

IHDI classification for DDH (not requiring the presence of an ossific nucleus). H-line is Hilgenreiner’s line drawn through the top of the tri-radiate cartilages bilaterally. P-line is Perkin’s line drawn perpendicular to the H-line at the superolateral margin of the acetabulum. D-line is diagonal line drawn 45 degrees from the junction of H-line and P-line. H-point is the midpoint of the superior margin of the ossified metaphysis. Grade I: the H-point is at or medial to the P-line. Grade II: the H-point is lateral to the P-line and at or medial to the D-line. Grade III: the H-point is lateral to the D-line and at or inferior to the H-line. Grade IV: the H-point is superior to the H-line.