Patient demographics
This study contained a total of 64 patients, including 37 males and 27 females. Modified group included 27 patients with the average age of 43.0 years (range: 26-60 years). This group contained 18 males and 9 females. Conventional group included 37 patients with the average age of 45.7 years (range: 29-59 years), which is consisted of 19 males and 18 females. No statistically difference was discovered between the two groups in age and gender (p >0.05). All the patients in this study got the TLICS scores of equal to or more than 4 points, which suggests operative treatment according to the Thoracolumbar Injury Classification and Severity score (TLICS). As for lumbar fracture level in modified group, 20 patients were in L1 and 7 in L2. And in the conventional group, 21 in L1 and 16 in L2. The high falling was the most common injury mechanism in both groups, followed by the road traffic accident. There were no significant differences for TLICS scores, fracture level and mechanism of injury (p > 0.05). There was one wound infection in each group respectively. All these complications were treated conservatively with complete resolution. No other serious complications such as blood vessel injury, spinal cord or nerve root injury related to surgery were observed in both groups. In all cases, fusions healed well and no revision surgery was performed for loss of correction or failure of instrumentation during follow-up.
Table 1 Patient demographic and injury details
Index
|
Modified group
|
Conventional group
|
p value
|
Number of patients
|
27
|
37
|
|
Mean age(year)
|
43.0
|
45.7
|
0.223
|
Gender
|
|
|
|
Male
|
18
|
19
|
0.220
|
Female
|
9
|
18
|
Mechanism of injury
|
|
|
|
Vehicle accident
|
1
|
2
|
1.000
|
Falling
|
26
|
35
|
Level of fracture
|
|
|
|
L1
|
20
|
21
|
0.154
|
L2
|
7
|
16
|
TLICS score
|
|
|
|
4
|
8
|
19
|
0.280
|
5
|
5
|
6
|
6
|
2
|
0
|
7
|
5
|
6
|
8
|
7
|
6
|
Surgical complications
|
|
|
|
Wound infection
|
1
|
1
|
1.000
|
Comparison of clinical data
As shown in Table 2, the mean operative time in modified group is significantly longer than conventional group (130.4±32.4min in modified group, 115.3±26.8min in conventional group, p = 0.046). The total volume of blood loss was 290.7±186.1ml in the modified group and 255.4±209.1ml in the conventional group, which was not statistically significant (p = 0.487). The postoperative drainage was 261.9±153.4ml in the modified group and 292.9±147.5ml in the conventional group, which was also not statistically significant (p = 0.417). Also, the VAS scores between two groups were similar for both groups (p > 0.05) (Table 2).
Table 2 Operation values and VAS score
Operative Characteristic
|
Modified group
|
Conventional group
|
p value
|
Operating time(min)
|
130.4±32.4
|
115.3±26.8
|
0.046
|
Blood loss(ml)
|
290.7±186.1
|
255.4±209.1
|
0.487
|
Postoperative drainage(ml)
|
261.9±153.4
|
292.9±147.5
|
0.417
|
VAS score
|
|
|
|
Pre-operative
|
7.4±1.0
|
7.2±1.2
|
0.581
|
Post-operative
|
4.2±1.3
|
4.1±1.1
|
0.966
|
Last follow-up
|
2.0±1.3
|
2.0±1.0
|
0.972
|
Comparison of radiological data
Local kyphosis angle (LKA)
The average preoperative LKA was 13.8°±7.2° in modified group and 10.7°±5.5° in conventional group, which was significantly corrected to 4.7°±4.6° and 4.1°±3.8° (all p < 0.05) after surgery, respectively. Post-operative correction was slightly better in modified group (66.9%) than in conventional group (64.5%) without no statistical relevance (p = 0.725). There was a loss (mean 2.5° in modified group and 4.5° in conventional group) in the final follow-up, resulting in a mean LKA of 6.1°±6.2° and 8.8°±5.1°, respectively. Correction loss in modified group was slightly less than in conventional group. However, this difference was also not statistically significant (p = 0.186). These results are summarized in Table 3. To conclude, the two groups were similar both in terms of post-operative sagittal alignment restoration and correction loss at last follow-up.
Anterior vertebral height (AVH)ratio of the fractured vertebra
Significant improvement in the AVH ratio (97.9%±6.7% in modified group, 94.1±7.8 in conventional group, p =0.043) was found postoperatively, (100.1%±9.7% in modified group, 89.6%±6.7% in conventional group, p =0.001) at the 3-month follow-up and(98.8%±7.7% in modified group, 90.9%±7.6% in conventional group, p =0.002) at the final follow-up. Post-operative correction was significantly better in modified group (45.0%) than in conventional group (38.8%, p=0.007). There was a loss (mean 0.6% in modified group and 2.6% in conventional group) in the final follow-up. Correction loss in modified group was slightly less than in conventional group without no statistical relevance (p = 0.227). Changes of the AVH ratio, which reflect the fracture-induced wedge shape of the vertebral body, are presented in Table 3. To conclude, modified surgical method resulted in a better reconstruction of the original shape of the vertebral body than conventional surgical method postoperatively. However, they shown no significant difference in correction loss at last follow-up. Figure 4 shows a representative case in the modified group.
Table 3 Comparison of radiological data between groups
|
Modified group
|
Conventional group
|
p value
|
Local kyphosis angle (LKA)
|
|
|
|
Pre-operative
|
13.8±7.2
|
10.7±5.5
|
0.060
|
Post-operative
|
4.7±4.6
|
4.1±3.8
|
0.574
|
Follow-up at 3 months
|
5.7±4.4
|
8.0±4.7
|
0.147
|
Last follow-up
|
6.1±6.2
|
8.8±5.1
|
0.116
|
Correction loss
|
2.5±5.4
|
4.5±4.5
|
0.186
|
Correction (%)
|
66.9±27.1
|
64.5±26.2
|
0.725
|
Anterior vertebral
height ratio (%)
|
|
|
|
Pre-operative
|
52.9±10.0
|
55.2±6.7
|
0.263
|
Post-operative
|
97.9±6.7
|
94.1±7.8
|
0.043
|
Follow-up at 3 months
|
100.1±9.7
|
89.6±6.7
|
0.001
|
Last follow-up
|
98.8±7.7
|
90.9±7.6
|
0.002
|
Correction loss
|
0.6±4.5
|
2.6±6.5
|
0.227
|
Correction
|
45.0±9.6
|
38.8±8.2
|
0.007
|
Neurological outcome and complications
Based on muscle strength classification, at admission 13 patients (48.15%) had Grade V muscle strength; five patients (18.52%) had Grade IV muscle strength, and nine patients (33.33%) had Grade I to III muscle strength in modified group. Follow-up muscle strength was evaluated as following: Grade V muscle strength (21 patients: 77.78%), Grade IV muscle strength (three patients: 11.11 %), and Grade I to III muscle strength (three patients: 11.11 %). In a word, 14 patients out of 27 (51.9 %) showed muscle strength improvement (Table 4).
As for conventional group, 28 patients (75.68%) had Grade V muscle strength; seven patients (18.92%) had Grade IV muscle strength, and two patients (5.41%) had Grade I to III muscle strength at admission. At follow-up, 34 patients (91.89) had Grade V muscle strength and 3 patients (8.11%) Grade IV muscle strength. In conventional group, seven patients out of 37 (18.92%) showed muscle strength improvement (Table 4). Patients with incomplete paralysis in the modified group were more than those in conventional group before operation, while statistical analysis showed no difference in postoperative muscle strength between the two groups (p > 0.05).
In modified group, at admission eight patients (29.63%) had dysuria and four patients (14.81%) still had dysuria after operation, which means four patients out of 27(14.81%) showed neurological improvement (Table 4). In conventional group, at admission eight patients (21.62%) had dysuria and one patient (2.70%) still had dysuria postoperatively, which means seven patients out of 37(18.92%) showed neurological improvement (Table 4). Statistical analysis showed no difference between the two groups (p > 0.05).
Complications included one urinary infection and two deep wound infection, one in each group. All these complications were treated conservatively with complete resolution. What’s more, instrumentation failure such as bending, loosening, or breakage of the pedicle screws was not observed in any patient during the follow-up period.
Table 4 Comparison of Neurological outcome and complications between groups
|
Modified group
|
Conventional group
|
p value
|
Preoperative muscle strength
|
|
|
|
I-III
|
9
|
2
|
0.011
|
IV
|
5
|
7
|
V
|
13
|
28
|
Postoperative muscle strength
|
|
|
|
I-III
|
3
|
0
|
0.117
|
IV
|
3
|
3
|
V
|
21
|
34
|
Preoperative dysuria
|
8
|
8
|
0.563
|
Postoperative dysuria
|
4
|
1
|
0.153
|
Complications
|
|
|
|
Deep wound infection
|
1
|
1
|
1.000
|
Urinary infection
|
0
|
1
|
1.000
|