Table 1.

Examples of studies tested different classification systems of DRF.

Study	Classification systems tested	No. of patients	No. of observers	Reliability
				Interobserver	Intraobserver
Andersson et al. 1996 [2]	Frykman	55	4	Fair	Fair–moderate
	Melone			Fair	Fair–moderate
	Mayo			Moderate	Fair–moderate
	AO			Fair	Fair
Flinkkilä et al. 1998[7]	AO	30	5	Poor–fair	Not tested
Illarramendi et al. 1998 [9]	Frykman	200	3	Moderate	Substantial
	AO			Fair	Moderate
Filho et al. 2004 [5]	Frykman	40		Fair	Moderate
	AO			Poor	Fair
	Universal			Fair	Moderate
Jin et al. 2007 [10]	AO	43	3	Fair–moderate	Fair–moderate
	Frykman			Fair–moderate	Moderate
	Cooney			Fair–moderate	Moderate–substantial