Demographic data
In current study, the mean age of patients was (41.35 ± 6.50) years. Younger patient was 29 years old and the older patient was 50 years old. Male represents (36.7%) from the sample, female represents (63.3%) of the sample. There were no significant differences between means of age between two study groups ((group A (41.26 ± 6.45) and group B (41.43 ± 6.66)). (t=-0.098, P=0.922).
Regarding gender, the percentage of both male and female are equal between two groups; 11 males (36.7%) and 19 females (63.3%).
Primary outcome measure: (Oswestry Disability Index)
The distribution of group A patients, according to ODI pre-operatively and 1week, 3 months, 6 months and 12 months postoperatively, was shown in figure 1. Before surgery, 40% of patients had severe disability, 43% of patients had moderate disability and 17% of patients had crippled disability, while after operations all patients had minimal disability in 4 postoperative periods of assessments.
The distribution of group B patients, according to ODI pre-operatively and 1week, 3 months, 6 months and 12 months postoperatively, was shown in figure 2.Before surgery, 33% of patients had severe disability, 53% of patients had moderate disability and 13% of patients had crippled disability, while after surgery all patients had minimal disability in 4 postoperative periods of assessments.
Secondary outcome measures
A/ VAS for back pain between group A and group B
The mean differences of post-operative VAS for back pain between study groups, including (group A and group B) in four periods of assessments, were shown in figure 3. There were significant differences between means of post-operative VAS for back pain between these two groups after one weeks (3.7 in group A versus 2.2 in group B) (t= 13.28, P=<0.001٭) and after 3 months (1.73 in group A versus 0.43 in group B) (t=10.54, P=<0.001٭), while non-significant differences between two groups after six months of operation (0.23 in group A versus 0.23 in group B) (t=0.00, P=1.000) and twelve months of operation (0.06 in group A versus 0.2 in group B) (t=-1.523.00, P=0.134).
B/ VAS for leg pain between group A and group B
The mean differences of post-operative VAS for leg pain between study groups, including (group A and Group B) in four periods of assessments, were shown in figure 4. There were no significant differences between means of post-operative VAS for leg pain between these two groups after one weeks (1.5 in group A versus 1.3 in group B) (t= 1.046, P=0.3) and after 3 months( 0.6 in group A versus 0.5 in group B) (t=0.766, P=0.447).
C/ VAS for back pain in group A in different periods (multiple comparison)
The mean differences of VAS for back pain between pre-operative and post-operative assessments in four time periods (after 1 weeks, 3 months, 6 months and 12 months), for group A patients, were shown in table 1. There were significant differences between means of VAS for back pain in pre-operative assessment (7.73) and post-operative assessments in four time periods (3.7, 1.73, 0.23 and 0.06 respectively) (P<0.001).
Table 1: The mean differences of (VAS for back pain) between pre-operative and post-operative assessments in four time periods
Study variables
|
Periods of assessment
|
N
|
Mean
|
SD
|
P-value
|
VAS for back pain
|
VAS for back pain preoperatively
|
30
|
7.73
|
0.78
|
<0.001٭
|
VAS for back pain 1 weeks postoperatively
|
30
|
3.70
|
0.46
|
VAS for back pain 3 months postoperatively
|
30
|
1.73
|
0.44
|
VAS for back pain 6 months postoperatively
|
30
|
0.23
|
0.43
|
VAS for back pain 12 months postoperatively
|
30
|
0.06
|
0.25
|
Friedman Test, P ≤ 0.05 was significant.
D/ VAS for back pain in group B in different periods (multiple comparison)
The mean differences of VAS for back pain between pre-operative and post-operative assessments in four time periods (after 1 weeks, 3 months, 6 months and 12 months), for group B patients, were shown in table 2.There were significant differences between means of VAS for back pain in pre-operative assessment (7.66) and post-operative assessments in four time periods (2.2, 0.43, 0,23 and 0.2 respectively) (P<0.001).
Table 2: The mean differences of (VAS for back pain) between pre-operative and post-operative assessments in four time periods
Study variables
|
Periods of assessment
|
N
|
Mean
|
SD
|
P-value
|
VAS for back pain
|
VAS for back pain preoperatively
|
30
|
7.66
|
0.75
|
<0.001٭
|
VAS for back pain 1 weeks postoperatively
|
30
|
2.20
|
0.40
|
VAS for back pain 3 months postoperatively
|
30
|
0.43
|
0.50
|
VAS for back pain 6 months postoperatively
|
30
|
0.23
|
0.43
|
VAS for back pain 12 months postoperatively
|
30
|
0.20
|
0.40
|
Friedman Test, P ≤ 0.05 was significant.
E/ VAS for leg pain in group A in different periods (multiple comparison)
The mean differences of VAS for leg pain between pre-operative and post-operative assessments in four time periods (after 1 weeks, 3 months, 6 months and 12 months), for group A patients, were shown in table 3.There were significant differences between means of VAS for leg pain in pre-operative assessment (9.63) and post-operative assessments in four time periods (1.46, 0.56,0.0 and 0.0 respectively) (P<0.001).
Table 3: The mean differences of (VAS for leg pain) between pre-operative and post-operative assessments in four time periods
Study variables
|
Periods of assessment
|
N
|
Mean
|
SD
|
P-value
|
VAS for leg pain
|
VAS for leg pain preoperatively
|
30
|
9.63
|
0.49
|
<0.001٭
|
VAS for leg pain 1 weeks postoperatively
|
30
|
1.46
|
0.50
|
VAS for leg pain 3 months postoperatively
|
30
|
0.56
|
0.50
|
VAS for leg pain 6 months postoperatively
|
30
|
0.00
|
0.000
|
VAS for leg pain 12 months postoperatively
|
30
|
0.00
|
0.000
|
Friedman Test, P ≤ 0.05 was significant.
F/ VAS for leg pain in group B in different periods (multiple comparison)
The mean differences of VAS for leg pain between pre-operative and post-operative assessments in four time periods (after 1 weeks, 3 months, 6 months and 12 months), for group B patients, were shown in table 4. There were significant differences between means of VAS for back pain in pre-operative assessment (9.53) and post-operative assessments in four time periods (1.33, 0.46, 0.0 and 0.0 respectively) (P<0.001).
Table 4: The mean differences of (VAS for leg pain) between pre-operative and post-operative assessments in four time periods
Study variables
|
Periods of assessment
|
N
|
Mean
|
SD
|
P-value
|
VAS for back pain
|
VAS for back pain preoperatively
|
30
|
9.53
|
0.50
|
<0.001٭
|
VAS for back pain 1 weeks postoperatively
|
30
|
1.33
|
0.47
|
VAS for back pain 3 months postoperatively
|
30
|
0.46
|
0.50
|
VAS for back pain 6 months postoperatively
|
30
|
0.00
|
0.00
|
VAS for back pain 12 months postoperatively
|
30
|
0.00
|
0.00
|
C/ Hospital stay, time of returning to daily activities and Cost of surgery
The mean differences of length of hospital stay, time of returning to daily activity and cost of surgery between study groups including (group A and Group B) were shown in table 5. There were significant differences between means of length of hospital stay (2.10 in group A versus 1.06 in group B) (P<0.001), time of returning to daily activities (7.33 in group A versus 4.03 in group B) (P<0.001) and cost of surgery (1996.66 in group A versus 3003.3 in group B) (P<0.001).
Table 5: The mean differences of length of hospital stay, time of returning to daily activities and the cost of surgery between study groups
Study variables
|
Study group
|
N
|
Mean
|
SD
|
t-test
|
P-value
|
Length of hospital stay (days)
|
Group A
|
30
|
2.10
|
0.30
|
14.26
|
<0.001٭
|
Group B
|
30
|
1.06
|
0.25
|
Time of returning to daily activity (days)
|
Group A
|
30
|
7.33
|
0.84
|
14.73
|
<0.001٭
|
Group B
|
30
|
4.03
|
0.88
|
Cost ($)
|
Group A
|
30
|
1996.66
|
39.24
|
-85.95
|
<0.001٭
|
Group B
|
30
|
3003.33
|
50.74
|
C/ Post-operative complications
One patient, in group A, got superficial wound infection and was treated successfully by oral antibiotics and daily dressing.
D/ Rate and time of the recurrence of disc herniation during 4 years of follow up
The association between study group including (group A and group B) and the recurrence of disc herniation were shown in table 6. There was no significant association between study group and the rate of recurrence of disc herniation (5 patients in group A versus 4 patients in group B) (P=1.000)
Table 6 Association between study group and the recurrence
Study variables
|
Study group
|
Total
|
P-value
|
Odds
|
95% CI
|
Group A
|
Group B
|
Recurrence
Yes
No
Total
|
5 (16.7)
25 (83.3)
30 (100.0)
|
4 (13.3)
26 (86.7)
30 (100.0)
|
9 (15.0)
51 (85.0)
200 (100.0)
|
1.000
|
1.30
|
0.313-5.404
|
*P value ≤ 0.05 was significant.
The mean differences of time of the recurrence between study groups including (group A and Group B) were shown in table 7. There were no significant differences in means of time of the recurrence between study groups (29 months after operation in group A versus 27 months after operation in group B) (P=0.778)
Table 7: The mean differences in means of time of the recurrence between study groups
Study variables
|
Study group
|
N
|
Mean
|
SD
|
t-test
|
P-value
|
Time of recurrence
(months)
|
Group A
|
5
|
29.00
|
6.08
|
|
0.778
|
Group B
|
4
|
27.75
|
6.70
|
E/ Level of disability by ODI at time of recurrence of disc herniation during 4 years of follow up
The association between study group and type of disability on recurrence of disc herniation was shown in figure 5. There was no significant difference in the level of disability between the two groups at time of the recurrence. In group A, 2 patients had severe disability and 3 patients had moderate disability, while in group B, 2 patients had severe disability and 2 patients had moderate disability) (P=1.000)
E/ Reoperation rate and type of surgery for recurrent disc herniation within 4 years of follow up
The reoperation rate and type of intervention for the recurrent cases between the two groups were shown in figure 6. There were 5 recurrent cases in group A; 3 of them were treated by conservative treatment while 2 patients were treated by surgical decompression and posterior stabilization with pedicle screws, while in group B, there were 4 recurrent cases; 2 of them were treated by conservative treatment and other 2 patients were treated by microdiscectomy. There was no significant difference between two groups (P=0.365).