Table 1 Patient’s demographic data and comorbidity between posttraumatic osteoarthritis of the knee (PTOA) and primary osteoarthritis of the knee (primary OA)

Age^a (years)

56.5 (31.0-82.0)

63.8 (30.0-95.0)

<0.0001

 Male

70 (51.5%)

264 (36.9%)

0.001

 Female

66 (48.5%)

452 (63.1%)

 Normal (18 to <25 kg/m²)

14 (10.4%)

42 (5.9%)

0.025

 Overweight (25 to <30 kg/m²)

37 (27.4%)

128 (17.9%)

 Obesity (>30 kg/m²)

84 (62.7%)

544 (76.0%)

Smoking^b

8 (5.9%)

35 (4.9%)

0.627

Alcohol drinking^b

59 (43.4%)

255 (35.6%)

0.085

Comorbidity

PTOA

Primary OA

p value

 Yes

42 (30.9%)

365 (51.0%)

0.0002

 No

94 (69.1%)

351 (49.0%)

 1

7 (5.2%)

11 (1.6%)

<0.0001

 2

98 (73.1%)

424 (59.6%)

 ≥3

29 (21.6%)

276 (38.8%)

 1-3

70 (54.7%)

214 (30.4%)

<0.0001

 ≥4

58 (45.3%)

488 (69.6%)

Charlson Comorbidity Index^a

2.8 ± 1.4 (0.0-7.0)

3.6 ± 1.5 (0.0-10.0)

<0.0001