Table 4 Comparison of the HSS among the four groups before the operation and at the last follow-up (\(\overline{\text{x}}\) ± s)

< 23

60.61 ± 11.60

91.27 ± 10.37

30.66 ± 9.84

22.90

<0.001

23- < 25

62.49 ± 10.21

90.02 ± 11.16

27.53 ± 10.30

22.20

<0.001

25- < 30

61.36 ± 8.03

87.96 ± 10.87

26.60 ± 8.43

39.03

<0.001

≥30

59.63 ± 14.67

83.41 ± 14.90

23.78 ± 14.53

11.34

<0.001

F value (between groups)

0.787

4.564

P value (between groups)

0.502

0.004