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Table 1 Participant characteristics and item scores for the two studies

From: A questionnaire to identify patellofemoral pain in the community: an exploration of measurement properties

Groups Study 1-baseline Study 2
PFPa (N = 26) Soft-tissue (N = 30) Healthy (N = 28) (N = 110)
Patient characteristics
 Mean age (SD) in years 27 (7.8) 27 (6.8) 28 (5.9) 30 (9.9)
 Gender–female 10 (39 %) 14 (47 %) 14 (50 %) 58 (53 %)b
 Mean body mass index (SD) 26 (6.6) 26 (5.0)b 24 (3.5) 25 (4.4)c
Section 1:
 ‘Have you ever been to a doctor because of knee problems?’ Yes 22 (85 %) 30 (100 %) 5 (18 %) 36 (33 %)
 ‘Have you had pain or problems in the last year in or around the knee?’ Yes
  25 (96 %) 28 (93 %) 2 (7 %) 38 (35 %)
Section 2: Clinical features
 In which knee have you had pain or problems? Both 16 (62 %) 5 (17 %) 1 17 (15 %)
 Have you had surgery to your knee? No 25 (96 %) 27 (90 %) 2 4 (4 %)
 Have you ever had a knee cap that has gone out of joint (dislocated)? No 25 (96 %) 26 (90 %)b 2 2 (2 %)
 Since starting with your knee problem, does your knee ever swell up? No 11 (42 %) 4 (13 %) 2 15 (14 %)
 Have you had pain and discomfort for more than one month? Yes 22 (85 %) 13 (43 %) 1 16 (15 %)
 Thinking about your right (left) knee, what do you consider is your main problem with your knee? Pain and discomfort 25 (96 %) 23 (77 %) 2 34 (31 %)
 Thinking about your right (left) knee, did your current knee problem come on? Gradually 21 (81 %) 4 (13 %) 0 18 (16 %)
 Total mean (SD) score for section 2 5.5 (0.91)d 3.4 (1.22)d 0.36 (1.31)d 1.6 (2.31)
Section 3: activity related pain
Because of your knee problems would you suffer from pain or difficulty with:
 Sitting for a long time Yes 16 (62 %) 17 (57 %) 1 11 (10 %)
 Going upstairs Yes 21 (81 %) 29 (97 %) 1 19 (17 %)
 Going downstairs Yes 17 (65 %) 24 (80 %) 1 12 (11 %)
 Squatting Yes 20 (77 %) 30 (100 %) 1 20 (18 %)
 Standing for long periods No 12 (46 %) 4 (13 %) 2 22 (20 %)
 Walking on a level surface No 13 (50 %) 6 (21 %)b 2 29 (26 %)
 Getting out of a chair Yes 23 (89 %) 20 (67 %) 0 6 (5 %)
 Kneeling Yes 21 (81 %) 29 (97 %) 0 26 (24 %)
 Walking on uneven surfaces No 7 (27 %) 4 (13 %) 1 24 (22 %)
 Walking down slopes Yes 17 (65 %) 24 (80 %) 1 20 (18 %)
 Walking up slopes No 7 (27 %) 3 (10 %) 1 23 (21 %)
 Hopping Yes 17 (65 %) 29 (97 %) 2 14 (13 %)
 Jumping Yes 18 (69 %) 27 (90 %) 2 16 (15 %)
 Running Yes 19 (73 %) 39 (100 %) 2 20 (18 %)
 Total mean (SD) score for section 3 9.2 (1.43) 8.8 (1.80) 0.61 (2.33)e 6.9 (2.40)
Section 4: knee pain map
 Total mean (SD) score for section 4 2.3 (1.40)d 0.6 (0.73)d 0.0 (0.00)d 0.62 (1.34)
Total mean (SD) score
All sections combined 16.6 (2.73) d 13.2 (1.67)d 1.0 (3.54)d -----------
Section 2 and 4 combined 7.8 (1.74) d 4.0 (1.50)d 0.4 (1.31)d 2.2 (3.38)
  1. adiagnostic criteria agreed with recruiting physiotherapist
  2. b1 missing value c4 missing values
  3. dSignificantly different from either group P < 0.001
  4. eSignificantly different from both the other groups P < 0.001
  5. Two participants in the healthy group responded that they had knee pain and completed the sections 2, 3, 4; Participants in the healthy group who responded they did not have a knee problem (and did not complete any other sections) were given a score of 0 for each section and a total score of 0 (see box)