Measurement: anteroposterior X-rays of the pelvis showing both femoral heads
Parameters:
(1) height of epiphysis (a) on the normal side (maximum thickness along articular surface)
(2) width of the epiphysis (b) on the normal side (breadth of the femoral head)
(3) height of the epiphysis (A) on the affected side
(4) width of the epiphysis (B) on the affected side
epiphyseal index on the normal side =
= (height of epiphysis on normal side) / (width of the epiphysis on normal side)
epiphyseal index on the affected side =
= (height of epiphysis on affected side) / (width of the epiphysis on affected side)
epiphyseal quotient =
= (epiphyseal index on affected side) / (epiphyseal index on normal side) =
= 100 * (height of epiphysis on affected side) * (width of the epiphysis on the normal side / ((width of the epiphysis on affected side) * (height of the epiphysis on the normal side))
Interpretation:
• Mose (1964) used a quotient of 60 to separate normal from flattened sphericity, with a value > 60 indicating a normal sphericity.
• Katz (1957) used a quotient of 75 to separate normal from flattened sphericity.
Limitation:
• One hip has to be normal so that it can serve as an adequate reference value.
