Background
Methods
Development of the questionnaire
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) |
Study one
Study two
Analysis
BOX: Scoring of the questionnaire Section 1: Participants were first asked ‘Have you had pain or problems in the last year in or around the knee?’ if they answered yes, they went onto complete section 2 to 4. Participants who 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. Scoring of sections Section 2: A score of one was given for each positive response to a clinical feature indicative of PFP: gradual onset, bilateral problem, pain for one month or more, main problem pain and discomfort. A score of one was given for a negative response to features not indicative of PFP: swelling, previous surgery, dislocation. In the presence of bilateral pain, a maximum score of 1 was given for each clinical feature. Scores were totalled. The minimum score was 0 and the maximum score was 7 for this question. Participants who did not have a knee problem (and did not complete any other sections) were given a score of 0. Section 3: Negative responses to questions relating to standing for long periods, walking up slopes, walking on uneven surfaces and walking on level surfaces were given a score of 1. Positive responses to all other activities were given a score of 1. In the presence of bilateral pain, a maximum score of 1 was given for each activity. Scores were totalled. The minimum score was 0 and the maximum score was 14. Participants who did not have a knee problem (and did not complete any other sections) were given a score of 0. Section 4: A score of 1 was given for each region on the knee pain map which covered the patellar (i.e., medial patella, lateral patella and patella tendon) to give a total score of 3 for each knee. The minimum score was 0 and the maximum score was 6. Finalised total score for questionnaire In the finalised scoring of the questionnaires only the sum scores for sections 2 and 4 were included. The sums of these sections were added together to give a total score. The total score for the questionnaire was between 0 and 13. Participants with knee problems who had a score of 6 or more were considered to have PFP. |
Study one
Study two
Sample size
Results
Study one
PFP group vs all others | PFP group vs all others with knee pain | PFP group vs soft tissue group | |
---|---|---|---|
Section 2 | 0.94 (0.90 to 0.99) | 0.90 (0.82 to 0.98) | 0.91 (0.84 to 0.99) |
Section 3 | 0.70 (0.58 to 0.81) | 0.45 (0.30 to 0.61) | 0.44 (0.29 to 0.53) |
Section 4 | 0.92 (0.84 to 0.99) | 0.88 (0.79 to 0.98) | 0.88 (0.78 to 0.97) |
Section 2 and 3 | 0.87 (0.79 to 0.95) | 0.77 (0.64 to 0.90) | 0.77 (0.64 to 0.90) |
Section 2 and 4 | 0.97 (0.94 to 1.00) | 0.95 (0.90 to 1.00) | 0.95 (0.90 to 1.00) |
Section 3 and 4 | 0.85 (0.77 to 0.93) | 0.73 (0.59 to 0.88) | 0.72 (0.58 to 0.87) |
All sections | 0.93 (0.87 to 0.99) | 0.88 (0.78 to 0.98) | 0.88 (0.78 to 0.98) |