Table 3 Comparison of the KSFS among the four groups before the operation and at the last follow-up (\(\overline{\text{x}}\)  ± s)

< 23

55.44 ± 13.06

89.83 ± 12.76

34.39 ± 15.59

16.21

<0.001

23- < 25

53.16 ± 10.48

87.47 ± 14.74

44.31 ± 20.77

17.72

<0.001

25- < 30

54.39 ± 20.27

85.01 ± 19.51

30.62 ± 21.28

17.80

<0.001

≥30

52.63 ± 16.11

82.28 ± 20.67

29.65 ± 19.61

10.48

<0.001

F value (between groups)

0.317

1.824

P value (between groups)

0.813

0.143