(range : 6-47) and 14.63±9.44 months (range : 3-30) in the non- od (p>0.05, Mann-Whitney U test). The corresponding values fusion and fusion group, respectively (p=0.885, Mann-Whitney were 4.05±3.98°, 6.35±3.87°, and 8.15±2.79° in the non-fusion U test) (Table 1). The statistical significance was not exist be- group while 5.83±5.50°, 10.16±8.15°, and 11.98±6.60° in the fu- tween the two groups (p>0.05). sion group, respectively. Patients of both groups achieved satisfactory clinical out- There were no cases of major complication such as wound in- comes by modified Mcnab criteria. The results showed that 9 fection, cerebrospinal fluid leakage, postoperative neurological patients had excellent and 14 patients had good outcome in the deficit or hardware failure. During the follow-up period, there non-fusion group; 5 patients and 11 patients in the fusion group, were no patients who underwent revision surgery or that for the respectively. Therefore, the proportion of patients whose treat- removal of instrument. ment 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 DISCUSSION indicated that there were no significant differences in clinical outcomes between the two groups (p=0.714, Fisher’s exact test) Thoracolumbar burst fractures are most common in patients (Table 2). with spine injuries. The most commonly utilized system for clas- The mean kyphotic angle at the time of immediate postoper- ative 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 (Fig. 3). 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 (Table 3). Also, the mean loss of kyphosis correction was evaluated and demonstrated in Table 3, 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 aver- age 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 postero- Excellent lateral fusion. The difference was not significant between the Good two groups at any time points of the follow-up (p>0.05, Mann- Fair Whitney U test) (Table 3). Poor In addition, we also compared the effect of fixed levels (i.e., ≥Good short versus long) on the loss of kyphosis correction between the two groups (Table 4). The mean loss of correction in 21 patients with poste- rior short segment pedicle screw fixa- tion were not significantly different ac- cording to p osterolateral fusion Immediately (p>0.05, Mann-Whitney U test). The postoperative results at each follow-up period were as 3 months follow-up follows : 15 patients in the non-fusion 6 months follow-up group, the average loss of correction 12 months follow-up 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 Short Long months, 1.84°; 12 months, 7.99±3.12° p-value Non-fusion Fusion Non-fusion Fusion in the fusion group. Similarly, 25 pa- 3 months follow-up 3.32±2.67° 3.71±3.77° 0.70 4.05±3.98° 5.83±5.50° tients who underwnet posterior long 6 months follow-up 5.33±3.53° 1.84°* 0.44 6.35±3.87° 10.16±8.15° segment pedicle screw fixation showed 12 months follow-up 6.09±3.17° 7.99±3.12° 0.32 8.15±2.79° 11.98±6.60° no statistical difference between non- *Only 1 patient was assessed at this follow-up fusion and fusion at any follow-up peri- Table 3. Radiological results : mean kyphotic angle and loss of kyphosis correction Mean Kyphotic Angle Loss of Correction Non-fusion Fusion Non-fusion Fusion 5.05±7.86° 3.94±8.67° Posterior Fixation Alone in Thoracolumbar Fractures | JU Hwang, et al. Table 4. Comparison of radiological results between the two groups : loss of kyphosis correction based on the fixed segments (short versus long segment) Fig. 3. Changes of kyphotic angle : comparison between two groups. Table 2. Clinical outcome assessment by modified Mcnab criteria 8.69±9.57° 9.36±11.26° 11.66±7.04° 16.57±9.51° 10.70±10.65° 16.73±10.36° 3.65±3.27° 5.72±3.54° 6.77±3.05° 349 18 16 14 12 10 8 6 4 2 0 p-value 0.47 0.39 0.10 p-value 0.55 0.55 0.30 Post-op immediate 3 months 6 months 12 months Non-fusion Fusion Fusion group 5 11 2 1 16 (84.2%) Non-fusion group 9 14 4 - 23 (85.2%) 5.24±5.06° 9.33±8.13° 10.84±5.87°