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Table 1 Sample characteristics by study groups

From: Validation of the Questionnaire to Identify Knee Symptoms (QuIKS) using Rasch analysis

Characteristics Known groups
  Healthy knees, n = 55 Knee pain, n = 111 Knee osteoarthritis (pre-HTO), n = 34 Knee pain and pre-HTO, n = 145
Age, years     
 Mean (SD) 24.7 (4.4) 52.1 (6.8) 48.9 (6.5) 51.3 (6.8)
Sex     
 Female (%) 35 (63.6) 62 (55.4)a 9 (36.0) 71 (49.0)
BMI, kg/m2     
 Mean (SD) 22.9 (3.1) 28.1 (9.1) 29.1 (4.7) 28.3 (8.3)
Affected knee     
 Unilateral (%) 1 (1.8) 61 (55.0) 18 (52.9) 79 (54.5)
 Bilateral (%) 4 (7.3) 49 (44.1) 16 (47.1) 65 (44.8)
 None (%) 50 (90.0) 1 (0.9) 0 1 (0.7)
Family history of arthritis     
 Yes (%) 23 (42.6)a 52 (46.8)a 11 (33.3)a 63 (43.4)b
History of knee injury     
 Yes (%) 3 (5.5) 77 (69.4)c 23 (71.9)b 100 (69.0)d
History of knee pain     
 Yes (%) 2 (3.6) 51 (45.9) 32 (100)b 83 (57.2)e
Kellgren and Lawrence Grade, Number of knees with Grade 0/1/2/3/4 -- -- 0/10/20/11/4 --
KOOS, range = 0–100 (worst to best state), median (IQR)     
 Other symptoms 100 (7.1) 53.6 (19.6) 37.5 (29.5) 53.6 (21.4)
 Pain 100 (2.8) 80.6 (27.8) 48.6 (23.6) 72.2 (30.6)
 ADL 100 (0) 89.7 (23.2) 58.8 (27.7) 80.9 (29.4)
 Sport & Recreation 100 (0) 75.0 (40.0) 17.5 (39.1) 58.0 (50.0)
 QOL 100 (0) 68.8 (31.3) 15.6 (31.3) 56.3 (43.8)
  1. Kellgren and Lawrence grade severity: 0 (normal) is no OA; 1 (doubtful) is possible joint space narrowing and osteophytes, 2 (minimal) is definite joint space narrowing and osteophyte, 3 (moderate) is definite joint space narrowing, multiple osteophytes, some sclerosis and possible bone contour deformity, 4 (severe) is marked joint space narrowing, large osteophytes, severe sclerosis and definite bone contour deformity [20]
  2. BMI body mass index, KOOS knee injury and osteoarthritis outcome score, ADL activities of daily living, QOL quality of life, IQR inter-quartile range
  3. Missing data a n = 1, b n = 3, c n = 4, d n = 9, e n = 2