J Korean Neurosurg Soc 52 | October 2012 sification of thoracolumbar fractures is presented by Denis10). According to the Denis 3-column concept, burst fractures con- sist of anterior and middle columns injury with retropulsion of bone fragments into the spinal canal, which is the radiographic hallmark22,23,41). In addition, McAfee et al.20) distinguished an unstable burst fracture from stable burst fracture based on the disruption of the posterior elements. Although a substantial number of literatures have reported the treatment of thoracolumbar fractures, it still remains con- troversial. It is generally known that unstable burst fractures re- quire surgical management. Since Roy-Camille et al.28) first in- troduced the plates with pedicle screw fixation, various operative techniques have been developed. Thereafter, Dick et al.11) used “fixateur interne” for the internal fixation. Since then, posterior short segment pedicle screw fixation has become the most pop- ular method for the surgical management of thoracolumbar fractures. As compared with a conventional long segment fixa- tion, short segment constructs provide the advantage of saving motion segments19,27,29,34,39). Furthermore, Tezeren and Kuru34) reported that there was no significant difference in the clinical outcome between the two methods. Despite the superiority of this method, many surgeons have reported that an early im- plant failure and a loss of the correction are the most important disadvantages16,21,30). In the current study, 21 patients underwent a posterior short segment pedicle screw fixation with or without posterolateral fusion. Even though short segment fixation could not avoid the loss of kyphosis correction, there were no instances of hardware failure in the present study. Besides, clinical outcomes accord- ing to the modified Mcnab criteria, above grade ‘good’ were ob- served in 17 patients (80.1%), which was not significantly dif- ferent from that of the long segment fixation (22 of 25, 88.0%). Most clinicians believe that kyphotic deformity of the thoraco- lumbar spine precipitate poor clinical outcomes, but the rela- tionship between them is unclear. Some authors advocated that there is no proven association between kyphosis and back pain or functional impairment5,24,40). Likewise, the present study showed satisfactory clinical outcomes in spite of correction loss. Traditional standard concept of surgical treatment for spinal fracture includes a concurrent internal fixation and a fusion method. To date, the internal fixation devices have greatly facil- itated the management of thoracolumbar fractures. But if a bone fusion could not be achieved, the instrumentation eventu- ally would be fatigued and failed. Solid fusion is well known to decrease the risk of hardware failure, but it restrains the spinal motion permanently and increases stress on the adjacent lev- els1,2,6,26,39). Consequently, the necessity of fusion as a supple- ment to instrumentation for the treatment of thoracolumbar burst fractures is always controversial. To our knowledge, there are only a few studies that have re- ported good clinical results of pedicle screw fixation without fu- sion for the treatment of thoracolumbar burst fractures. Sander- son et al.29) conducted a retrospective study of 28 patients who underwent a short segment screw fixation without fusion. Ac- cording to these authors, there was no significant correlation between the radiological parameters and clinical outcomes. They considered that a routine posterior or posterolateral fu- sion would be unnecessary in the operative management of thoracolumbar burst fracture. Wang et al.39) prospectively com- pared the clinical results between fusion and non-fusion groups with short segment posterior fixation (28 and 30 patients, re- spectively). They found better perioperative parameters in the non-fusion group, and showed that there were no significant differences in the results of the radiological and functional as- sessment between the two groups. The short-term results of short segment fixation without fusion were satisfactory in that study. In a recently published paper, Dai et al.9) reported the long-term results of a prospective randomized trial involved 73 patients who underwent a posterior short segment screw fixa- tion with or without posterolateral fusion (37 and 36 patients, respectively). These authors reported that there were no signifi- cant differences in the radiographic or clinical outcomes be- tween the two groups, thus suggesting that posterolateral bone graft would not be mandatory. Consistently with previous studies, the current study showed that loss of kyphosis correction was not significantly different between the non-fusion group and the fusion group. The result of radiological assessment demonstrated that loss of correction progressed in both groups, regardless of posterolateral fusion. Furthermore, the loss of correction was compared under short versus long segment fixation and there was no significant dif- ference between the non-fusion group and fusion group. Satis- factory clinical outcomes, ‘excellent’ or ‘good’ according to mod- ified Mcnab criteria, were similarly observed in both groups and also there was no statistically significant difference between the two groups. The variables that affect the attainment of spinal fusion are complex and incompletely understood. Bone grafting is one of the most important factors in fusion surgery for the thoraco- lumbar fractures. There are many different types of bone graft, autologous iliac crest bone graft is considered the gold stan- dard. However, harvesting iliac crest bone leads to considerable donor site morbidity, such as risk of infection, hematoma, frac- ture, wound healing problems, and donor site pain. To avoid these complications, local bone graft and various bone graft substitutes have been used in posterolateral fusion. Controlled trials have demonstrated that posterolateral fusion with local bone graft may yield similar clinical and fusion outcomes as ili- ac crest bone graft25,31). Synthetic bone graft substitutes are often used in spinal fusion surgery and deemed to be efficient based on their osteoconductive properties. When combined with bone marrow aspirate or used as an extender for autologous bone graft, they are useful biomaterials for bone fusion. In the pres- ent study, patients of the fusion group underwent posterolateral fusion with autologous local bone graft and/or synthetic bone substitutes. 350