Table 1.

Graf classification system¹

Graf	Sonographic hip type	Bony roof	Ossific rim	Cartilage rim	Alpha angle
Ia	Mature	Good	Sharp	Long and narrow, extends far over femoral head	> 60
Ib	Mature	Good	Usually blunt	Short and broad, but covers femoral head	> 60
IIa	Physiological delay in ossification > 3 months (physiological immature but stable hips)	Deficient	Rounded	Covers femoral head	50 to 59
IIb	Physiological delay in ossification > 3 months (inherently stable)	Deficient	Rounded	Covers femoral head	50 to 59
IIc	On point of dislocation (unstable, requires immediate treatment)	Deficient	Rounded or flat	Covers femoral head	43 to 49
IId	On point of dislocation	Severley deficient	Rounded or flat	Compressed	43 to 49
IIIa	Dislocated (subluxation)	Poor	Flat	Displaced upwards and echo poor	< 43
IIIb	Dislocated (subluxation)	Poor	Flat	Displaced upwards and more reflective than femoral head	< 43
IV	Dislocated (complete)	Poor	Flat	Interposed	< 43

1. Karnik 2007