Table 1 Demographic features of 1112 patients who underwent total knee arthroplasty surgery

Age (years)

67.9 ± 7.9

0.036

 ≤ 65

396 (35.7)

7.9 ± 2.4

 >65

714 (64.3)

9.5 ± 3.6

Gender

0.441

 Female

927 (83.5)

8.3 ± 4.3

 Male

183 (16.5)

8.0 ± 4.2

Clinical protocol

< 0.01

 Traditional protocol

71 (6.4)

11.6 ± 2.3

 Current protocol

294 (26.5)

7.2 ± 1.9

Operative time(min)

89.3 ± 21.5

< 0.01

 ≤ 70

253 (22.8)

7.4 ± 4.0

 70–110

646 (58.3)

8.2 ± 4.3

 ≥ 110

210 (18.9)

9.5 ± 4.2

Surgeon

< 0.01

 1

297 (26.8)

7.9 ± 4.5

 2

320 (28.9)

8.57 ± 4.1

 3

306 (27.6)

7.4 ± 4.0

 4

186 (16.8)

10.2 ± 3.7

ROM

91.3 ± 18.0

< 0.01

 <90°

344 (35.4)

8.6 ± 4.4

 ≥ 90°

583 (64.6)

7.7 ± 4.1

Complications

< 0.01

 Yes

220 (19.8)

11.0 ± 4.2

 No

892 (80.2)

7.6 ± 4.0

Intraoperative blood loss(ml)

219.8 ± 120.5

< 0.01

 ≤ 150

291 (41.3)

7.7 ± 4.0

 150–300

287 (40.8)

8.2 ± 4.2

 ≥ 300

126 (17.9)

10.6 ± 4.0

Preoperative Hb(g/L)

127.9 ± 13.7

0.571

 ≤ 110

108 (9.7)

7.6 ± 4.4

 110–140

786 (70.8)

8.5 ± 4.3

 ≥ 140

116 (10.5)

7.3 ± 4.1

BI Score

0.512

 ≤ 90

576 (67.6)

7.3 ± 4.0

 >90

276 (32.4)

7.8 ± 4.2

Day of operation

0.221

 Monday

245 (22.0)

8.3 ± 4.4

 Tuesday

236 (21.2)

8.9 ± 4.1

 Wednesday

168 (15.1)

7.6 ± 3.9

 Thursday

212 (19.1)

8.4 ± 4.4

 Friday

210 (18.9)

8.1 ± 4.0

Type of pay

0.412

 Selfpay

577 (60.8)

8.0 ± 4.1

 Medicare

372 (39.2)

8.2 ± 4.4

Ward

< 0.01

 A

923 (83.2)

8.0 ± 4.2

 B

186 (16.8)

9.8 ± 4.1

Transfusion

< 0.01

 Yes

87 (7.8)

11.0 ± 5.2

 No

1025 (92.2)

8.1 ± 4.1

ASA classification

0.015

 I/II

920(82.7)

8.1 ± 3.5

 III/IV

192(17.3)

9.3 ± 4.1

Comorbidities

0.043

 Healthy

674

7.9 ± 4.

 Cardiovascular

85

8.5 ± 3.7

 Neurological

93

9.7 ± 3.2