Table 2 Demographic, clinical, symptom, and psychological characteristics of patients (N =156) prior to surgery

 Age

Years

68.9

9.1

n

%

 Sex

Female

106

67.9

 Cohabitation status

Married/partnered

95

60.9

 Employment status

Unemployed/retired

100

64.1

 Education level

College/university

76

48.7

Clinical characteristics

Mean

SD

Body mass index (BMI)

29.2

4.6

n

%

Obese (BMI ≥30 kg/m²)

61

39.1

Morbidly obese (BMI ≥40 kg/m²)

4

2.6

Mean

SD

Number of comorbidities (0–5)

1.2

1.0

American Society of Anesthesiologists’ physical status classification score

2.0

0.5

Systolic blood pressure

138.6

16.1

C-reactive protein

3.3

3.0

Creatinine

77.6

23.0

Pain characteristics

Average pain prior to surgery (0–10)

5.3

1.8

Worst pain prior to surgery (0–10)

5.5

2.1

Pain interference with function (0–10)

4.4

2.0

 Number of painful sites

Prior to surgery

2.1

1.6

12 months after surgery

2.0

1.2

n

%

Contralateral knee pain 12 months – yes (n = 130)

40

30.8

 Pain interference walking group

Recurrent interference group

36

23.1

Continuous improvement group

120

76.9

Perioperative characteristics:

 Anesthesia

Regional anesthesia

132

84.6

Total intravenous anesthesia

24

15.4

Mean

SD

Length of surgery (minutes)

65

13.0

Length of stay (days)

4.6

1.1

 Pain management

Average dose of opioids (mg)^a

12.6

6.2

n

%

Ketamine - yes

22

14.1

Preoperative symptoms

Mean

SD

Fatigue severity (1–10)

2.6

2.2

Fatigue interference (1–7)

3.9

1.5

Depression (0–21)

3.4

3.1

Anxiety (0–21)

4.6

3.7

Psychological characteristics^b

Consequences (0–10)

6.2

1.8

Personal control (0–10)

5.4

2.3

Identity (0–10)

6.6

1.7

Concern (0–10)

5.1

2.6

Emotional response (0–10)

4.5

2.6

Health status

Preoperative self-rated health

60.9

19.7

Self-rated health, 12 months

74.7

16.0