Table 2.

Comparison of PROMs used in patellofemoral instability literature

	Kujala	Lysholm	IKDC	Pedi-IKDC	KOOS	KOOS-Child	NPI	BPII 2.0
Year initially published	1993	1982	2001	2011	1998	2012	2012	2013
Original construct	Anterior knee pain	Ligament instability	Knee pathology	Knee pathology	Knee pathology including OA	Knee pathology	Patellofemoral instability	Patellofemoral instability
Target population	Adults	12 years to adult	Adults	10–18 years	16 years to elderly	7–18 years	Adults	10 years to adult
Number of items	13	8	18	13	42	39	19	23
Response options	Multiple choice	Multiple choice	Likert scale	Likert scale	Likert scale	Likert scale	Likert scale	VAS
Scoring	Variable point values for each selection	Variable point values for each selection	Weighted responses	Weighted responses	Normalized, domains reported separately	Weighted and normalized, domains reported separately	Weighted responses	Measured distance on VAS
Range of scores (worst to best)	0–100	0–100	0–100	0–100	0–100 for each domain	0–100	100–0	0–100
Completion time for patient	4 min	3 min	10 min	10 min	10 min	10–20 min	4 min	5 min
Normative data available	Yes^ [23] 100/100	Yes [46] 94/100	Yes [47] 86–89/100	Yes [48] 87.4/100	Yes [49] Variable	Yes [49] Variable	No	No
Original language	Finnish, published in English	Swedish, published in English	English	English	English and Swedish	Swedish and English	English	English
Available translations	> 10	> 5	> 10	Danish	> 50	> 5	German	German, French
Reading grade level*	5.0	5.7	8.7	5.6	4.8	4.7	5.9	7.1

*Reading level was calculated by using the composite grade level algorithm available at www.readability.io

^{^}n = 17 from original control group