Table 3.

Levels of evidence regarding quality criteria for the region- and disease-specific instruments used in TAA studies

Instrument/study	Reliability	Agreement	Internal consistency	MCID	Content validity	Criterion validity	Construct validity	Floor and ceiling effects	Responsiveness
AOFAS hindfoot score [21]	0*	0	0	0	0	0	2	+	2+
FFI [4]	1+	3	1+	0	+	1−	1+	†	3±‡
AOS [9]	3+	0	0	0	0	3+	3	0	0
Kofoed [22, 23]	0	0	0	0	0	0	0	0	0
Evanski and Waugh [11]	0	0	0	0	0	0	0	0	0
NJOH [5]	0	0	0	0	0	0	0	0	0
Takakura et al. [39]	0	0	0	0	0	0	0	0	0
Mazur et al. [29]	0	0	0	0	0	0	0	0	0
“Oxford” [18]	0	0	0	0	0	0	0	0	0

* Reliability investigated, but methods insufficient to assign an evidence level; ^†severe ceiling effects for the limitation subscale, moderate floor and ceiling effects for the pain and disability subscales; ^‡positive rating for the pain subscale, negative ratings for the limitation and disability subscales; 0 = no information available; 1 = Level 1 rating; 2 = Level 2 rating; 3 = Level 3 rating; + = positive rating; − = negative rating; MCID = minimal clinically important difference; AOFAS = American Orthopaedic Foot and Ankle Society; FFI = foot function index; AOS = Ankle Osteoarthritis Scale; NJOH = New Jersey Orthopaedic Hospital ankle score; “Oxford” = questionnaire developed by the authors, modeled to the validated Oxford Hip Score [7].