Table 2 Comparison of the KSS among the four groups before the operation and at the last follow-up (\(\overline{\text{x}}\) ± s)

< 23

46.24 ± 12.65

89.15 ± 7.26

42.91 ± 10.27

30.70

<0.001

23- < 25

47.31 ± 14.17

87.21 ± 13.26

39.9 ± 15.14

21.89

<0.001

25- < 30

49.23 ± 13.93

90.37 ± 9.31

41.14 ± 13.70

37.14

<0.001

≥30

45.98 ± 11.88

80.05 ± 16.51

34.07 ± 16.36

14.43

<0.001

F value (between groups)

1.120

10.344

P value (between groups)

0.341

<0.001