Table 4 Performance and self-reported measures of motor imagery practice (Mip) and control (CON) groups before and 1 month after surgery (per protocol analysis)

MViC extension (Nm/kg)

Operated leg

MIp

1.37 ± 0.35

0.80 ± 0.34

0.39 (0.03, 0.75)

Likely beneficial

CON

1.51 ± 0.38

0.55 ± 0.25

Non-operated leg

MIp

1.77 ± 0.32

1.77 ± 0.29

− 0.03 (− 0.39, 0.33)

Possibly negative

CON

1.63 ± 0.36

1.66 ± 0.35

Voluntary muscle activation (%)

Operated leg

MIp

80.08 ± 13.28

84.84 ± 9.75

21.26 (4.90, 37.62)

Very likely beneficial

CON

80.86 ± 14.13

64.36 ± 20.85

Non-operated leg

MIp

85.83 ± 9.48

81.42 ± 12.44

− 6.05 (− 18.22, 6.12)

Unlikely negative

CON

82.44 ± 9.65

84.08 ± 12.78

Knee flexion (degrees)

Operated leg

MIp

87.69 ± 9.66

82.31 ± 9.75

8.54 (− 6.04, 23.12)

Likely beneficial

CON

86.23 ± 18.08

72.31 ± 14.28

Non-operated leg

MIp

104.23 ± 8.16

106.54 ± 9.93

1.08 (− 10.57, 12.73)

Possibly beneficial

CON

105.54 ± 13.08

106.77 ± 11.10

Knee extension (degrees)

Operated leg

MIp

4.31 ± 3.25

7.15 ± 3.74

− 0.46 (− 4.39, 3.47)

Possibly negative

CON

3.08 ± 2.63

6.38 ± 4.56

Non-operated leg

MIp

2.54 ± 1.81

2.15 ± 1.86

− 0.93 (− 3.02, 1.16)

Unlikely negative

CON

1.38 ± 1.56

1.92 ± 2.36

VAS score (points)

Operated leg

MIp

53.85 ± 12.1

31.54 ± 12.14

− 5.00 (− 19.49, 9.49)

Unlikely negative

CON

54.62 ± 14.21

37.31 ± 14.67

Non-operated leg

MIp

8.46 ± 8.99

1.54 ± 3.76

− 0.39 (− 11.91, 11.13)

Possibly negative

CON

14.62 ± 13.61

7.31 ± 13.01

Hand grip strength, dominant arm (kg)

MIp

39.77 ± 9.61

38.85 ± 7.41

− 1.15 (− 12.29, 9.99)

Possibly negative

CON

36.54 ± 11.93

36.77 ± 11.41

TUG (s)

MIp

7.48 ± 1.52

7.55 ± 1.22

− 3.90 (− 6.02, − 1.78)*

Most likely beneficial

CON

7.57 ± 1.55

11.54 ± 3.01

OKS score (points)

MIp

21.92 ± 5.25

27.08 ± 5.17

7.46 (1.72, 13.20)

Very likely beneficial

CON

22.38 ± 6.23

20.08 ± 4.27