The distribution of age, sex, and level of fracture were similar between the two groups (). The non-fusion group included 27 patients (18 males and 9 females), the fusion group 19 patients (11 males and 8 females), with no significant difference between the two groups in terms of male/female ratio (p=0.544, chi-square test). The mean age of patients was 49.93±11.70 years (range : 26-71) in the non-fusion group and 49.11±19.56 years (range : 22-77) in the fusion group (p=0.871, Welch's t-test). The fracture levels at T12 was 9 cases; L1, 12 cases; L2, 4 cases, and L3, 2 cases in the non-fusion group. The fusion group had T12, 6 cases; L1, 9 cases, L2, 3 cases, and L3, only 1 case (p=0.802, Fisher's exact test). The number of fixed levels in terms of short versus long was comparable in both groups (p=0.108, chi-square test). In the non-fusion group, 15 patients underwent short segment fixation while long segment fixation was performed in 12 patients. Whereas in the fusion group, these numbers were 6 and 13, respectively. The average follow-up period was also similar in both groups, 16.07±11.45 months (range : 6-47) and 14.63±9.44 months (range : 3-30) in the non-fusion and fusion group, respectively (p=0.885, Mann-Whitney U test) (). The statistical significance was not exist between the two groups (p>0.05).
Demographic data of the patients
Patients of both groups achieved satisfactory clinical outcomes by modified Mcnab criteria. The results showed that 9 patients had excellent and 14 patients had good outcome in the non-fusion group; 5 patients and 11 patients in the fusion group, respectively. Therefore, the proportion of patients whose treatment outcomes were good or better was 23/27 (85.2%) in the non-fusion group and 16/19 (84.2%) in the fusion group. This indicated that there were no significant differences in clinical outcomes between the two groups (p=0.714, Fisher's exact test) ().
Clinical outcome assessment by modified Mcnab criteria
The mean kyphotic angle at the time of immediate postoperative was 5.05±7.86° (range : -17.62° to 17.93°) in the non-fusion group and 3.94±8.67° (range : -19.67 to 13.59°) in the fusion group. The follow-up kyphotic angles were assessed at the time of 3, 6 and 12 months after surgery (). The average angle at each follow-up period was as follows : which increased to 8.69±9.57° at 3 months follow-up; 6 months, 11.66±7.04°; 12 months, 10.70±10.65° in the non-fusion group and 3 months, 9.36±11.26°; 6 months, 16.57±9.51°; 12 months, 16.73±10.36° in the fusion group (). Also, the mean loss of kyphosis correction was evaluated and demonstrated in , which was 3.65±3.27°, 5.72±3.54°, and 6.77±3.05° at each follow-up period in the non-fusion group. In the fusion group, the average kyphotic angle was increased 5.24±5.06°, 9.33±8.13°, and 10.84±5.87°, respectively. These results demonstrated that loss of correction progressed in both groups, regardless of posterolateral fusion. The difference was not significant between the two groups at any time points of the follow-up (p>0.05, Mann-Whitney U test) ().
Changes of kyphotic angle : comparison between two groups.
Radiological results : mean kyphotic angle and loss of kyphosis correction
In addition, we also compared the effect of fixed levels (i.e., short versus long) on the loss of kyphosis correction between the two groups (). The mean loss of correction in 21 patients with posterior short segment pedicle screw fixation were not significantly different according to posterolateral fusion (p>0.05, Mann-Whitney U test). The results at each follow-up period were as follows : 15 patients in the non-fusion group, the average loss of correction was 3.32±2.67° at 3 months follow-up; 6 months, 5.33±3.53°; 12 months, 6.09±3.17° and 3 months, 3.71±3.77°; 6 months, 1.84°; 12 months, 7.99±3.12° in the fusion group. Similarly, 25 patients who underwnet posterior long segment pedicle screw fixation showed no statistical difference between non-fusion and fusion at any follow-up period (p>0.05, Mann-Whitney U test). The corresponding values were 4.05±3.98°, 6.35±3.87°, and 8.15±2.79° in the non-fusion group while 5.83±5.50°, 10.16±8.15°, and 11.98±6.60° in the fusion group, respectively.
Comparison of radiological results between the two groups : loss of kyphosis correction based on the fixed segments (short versus long segment)
There were no cases of major complication such as wound infection, cerebrospinal fluid leakage, postoperative neurological deficit or hardware failure. During the follow-up period, there were no patients who underwent revision surgery or that for the removal of instrument.