Table 1 Assessment criteria

Tönnis grades for DDH

 Grade I

Capital femoral epiphysis medial to Perkins line

 Grade II

Capital femoral epiphysis lateral to Perkins line,

but below the level of superior acetabular rim

 Grade III

Capital femoral epiphysis at the level of the superior acetabular rim

 Grade IV

Capital femoral epiphysis above the level of the superior acetabular rim

Functional assessment (modified Severin grading system)

 Grade I (satisfactory)

No pain, no limp, unlimited endurance

 Grade II (satisfactory)

No pain, slight limp, slight restriction of endurance

 Grade III (unsatisfactory)

Occasional pain, noticeable limp, endurance moderately restricted

 Grade IV (unsatisfactory)

Regular pain, marked limp, severe restriction of endurance

Radiographic assessment (Severin classification system)

 Grade I (excellent) (satisfactory)

Normal hip

CE angle > 15 degrees in children

CE angle > 25 degrees in adults

 Grade II (good) (satisfactory)

Mild deformity of head or neck

Hip deeply and concentrically reduced

CE angle as grade I

 Grade III (fair) (unsatisfactory)

Dysplastic hips without subluxation

CE angle < 15 degrees in children

CE angle < 20 degrees in adults

 Grade IV (poor) (unsatisfactory)

Subluxation

 Grade V (poor) (unsatisfactory)

Head articulating with a false acetabulum in the upper part of the original acetabulum

 Grade VI (poor) (unsatisfactory)

Redislocation

Kalamachi et al. femoral head AVN grades

 Grade I

Changes affecting the ossific nucleus

 Grade II

Lateral physeal damage

 Grade III

Central physeal damage

 Grade IV

Total damage to the femoral head and physis