Table 3.

Comparison of VAS scores of patients between the two groups before and at each time point after surgery ($\overline{x}$ ± S, score).

Group	Before surgery	2 weeks after operation	2 months after operation	6 months after operation
Study group (n = 42)	6.22 ± 1.41	4.23 ± 1.26a	3.10 ± 1.16ab	1.89 ± 0.98abc
Control group (n = 42)	6.29 ± 1.53	4.97 ± 1.33a	3.65 ± 1.27ab	2.25 ± 0.63abc
t	0.218	2.618	2.072	2.003
P	0.828	0.011	0.041	0.049

Note: “a” is P < 0.05, compared with that in the same group before surgery; “b” is P < 0.05, compared with that in the same group two weeks after surgery; “c” is P < 0.05, compared with that in the same group six months after surgery.