KumaFix fixation for thoracolumbar burst fractures: a prospective study on selective consecutive patients

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1 Xi an Hong Hui Hospital Xi an, Shaanxi, China KumaFix fixation for thoracolumbar burst fractures: a prospective study on selective consecutive patients Dingjun Hao, Baorong He, Liang Yan Hong Hui Hospital, Xi an Jiaotong University College of Medicine, Xi an, Shaanxi , China

2 ABSTRACT PURPOSE Short-segment U-shaped pedicle screw fixation has been widely used to treat thoracolumbar burst fracture. Some studies reported the disadvantages of traditional U-shaped pedicle screw, which included a relatively high rate of adjacent segment degeneration and screw failure including screw pullout and breakage. The purpose of this study was to assess efficacy of open reduction and fixation using KumaFix fixation system in treatment of thoracolumbar burst fractures.

3 METHODS From June 2011 to June 2012, 45 consecutive patients with thoracolumbar burst fractures were enrolled. They were randomly assigned to treatment with KumaFix (treatment group, n=23) or traditional U-shaped pedicle screw (control group, n=22). The patients were followed up postoperatively and were assessed with regard to radiologic and clinical outcomes. Radiologic outcomes were assessed mainly on the basis of Cobb angle and vertebral wedge angle. Clinical outcomes were evaluated mainly with use of visual analog scale (VAS) for pain and the Oswestry Disability Index (ODI) questionnaire.

4 RESULTS All patients were followed up from 9 to 22 months. There were no significant differences between the two groups with regard to preoperative indices. In the treatment group, the operation time was significantly lower than control group. Preoperative Cobb angles and vertebral wedge angles in two groups were significantly decreased after surgery, and these has been well maintained at the last follow up with mild correction losses. Results of clinical outcome showed lower VAS and ODI scores in two groups compared with those preoperative, and the treatment group had greater improvement on the ODI compared with the control group at the last follow up.

5 CONCLUSIONS Compared with traditional U-shaped pedicle screw, KumaFix fixation system can achieve gradually, controlled reduction, provide enough space for bone implantation, and avoid acceleration of adjacent segment degeneration. It is an effective and reliable technique to treat thoracolumbar burst fractures. Key words: Thoracolumbar burst fracture; Pedicle screw; Internal fixation; Posterior approach.

6 Figures and Tables Figure 1. The procedures of KumaFix fixation.

7 Figure 2. Preoperative and postoperative imaging of a 41-year-old male patient with L2 burst Fracture, type A3 with ASIA D neurological impairment. A, B. preoperative AP and lateral radiographs showed a L2 burst fracture with a Cobb angle of 12. C, D. 3d postoperative AP and lateral radiographs showed vertebral height was restored, angular deformity was corrected, and the connecting rods were located in the medial of the joint. E, F. postoperative sagittal and axial CT scans showed satisfied implantation of bone graft via the affected vertebral pedicle. G, H. postoperative AP and lateral radiographs at last follow up showed satisfied position of internal fixation and normal

8 thoracolumbar alignment without obvious correction loss. Table 1. Summary of patient s demographic data Treatment group Control group P value Number Sex (M/F) 15/8 14/ Age (years) 40.8± ± Time from injury to surgery 4.7± ± Level of fracture T T L L2 1 1 Preop Cobb angle 16.5± ± Preop vertebral wedge angle 20.4± ± Duration of follow up (months) 14.5± ± Table 2. Measurement of Cobb angle and vertebral wedge angles Treatment group Control group P 1 value Preop Cobb angle 16.5± ± d postop Cobb angle 3.8± ± Last Cobb angle 5.2± ± P 2 value P<0.001* P<0.001* Preop vertebral wedge angle 20.4± ± d postop vertebral wedge angle 9.7± ± Last vertebral wedge angle 11.2± ± P 2 value P<0.001* P<0.001* P 1 value: statistical results of Radiologic parmeters between treatment and control group P 2 value: statistical results within same group between preoperative and last follow up * P<0.05

9 Table 3. The changes of VAS and ODI results during follow up periods Treatment group Control group P 1 value Preop VAS 8.0± ± m postop VAS 4.4± ± m postop VAS 2.9± ± Last postop VAS 1.6± ± P 2 value P<0.001* P<0.001* Preop ODI 48.1± ± m postop ODI 40.4± ± m postop ODI 30.8± ± Last postop ODI 12.9± ±7.8 P<0.001* P 2 value P<0.001* P<0.001* P 1 value: statistical results between treatment and control group P 2 value: statistical results within same group between preoperative and last follow up * P<0.05

10 Disclosure of Conflicts of Interest We certify that all our affiliations with or financial involvement in, within the past 3 years and foreseeable future, any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript are completely disclosed.