Journal List > J Korean Soc Spine Surg > v.15(1) > 1035817

Kim, Kim, Kang, Kim, Kim, Sohn, Lee, and Lee: The Comparison of the Results Between AO Internal Fixator (Long lever-arm) and Screw-Rod System (Short lever-arm) Through Posterior Approach in Unstable Thoracolumbar Fractures

Abstract

Study design

Prospective study.

Objectives

To analyze the outcome of posterior reduction and fixation with the AO internal fixator and with the screw-rod system in unstable thoracolumbar fractures and to investigate differences in effectiveness between the two methods.

Summary of literature review

In unstable thoracolumbar fractures, fixation with the AO internal fixator is an effective method for posterior reduction. However, the results of correction are quite variable.

Materials and methods

We analyzed 51 patients with unstable thoracolumbar fractures who underwent correction through posterior approach between 1997 and 2003. We divided the patients into two groups: Patients in Group A (25 cases) were treated with the AO internal fixator, and patients in Group B (26 cases) were treated with the screw-rod system. We added transpedicular bone grafts for 17 patients in Group A. We evaluated correction of deformity (anterior and posterior height of vertebral body, sagittal index, disc height), loss of correction, spinal canal clearance, and neurological recovery.

Results

Comparing correction of deformity, we saw better results in Group A than in Group B in regards to sagittal index and anterior height of vertebral body. However, we saw a higher degree of correction loss in the anterior height of the vertebral body in Group A. We grafted autogenous bone into the fracture site by transpedicular approach for 17 patients in Group A. We saw less correction loss in the anterior vertebral body height and sagittal index. In regard to spinal canal clearance, we saw better results in Group A (18%) than in Group B (10%). As for neurological recovery, we could not find any statistically significant difference between the two groups.

Conclusions

Through an operative procedure, we could achieve better results in restoration of anterior vertebral height and canal clearance with the AO internal fixator system. Further study is necessary to keep the reduced state of vertebral height.

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Table 1.
Epidemiology in group A and group B
    Group A Group B Total
No. of cases   25 26 51
Instruments   AO internal screw-rod system  
    fixator    
Age (years)   35.1 41 37.7
Sex (M/F)   (12/13) (12/14) 24/27
Duration of follow-up   28.7 32 29.3
(months)        
Etiology fall-down 14 12 .326
  traffic accident 10 11 .321
  Others 11 13 29.3
Site of Fractures T12 16 14 .310
(No. of cases) L1 19 13 .322
  L2 19 17 .316
  Others 11 12 29.3
Bone graft Posterior + +  
  Transpedicular 17 -  
Table 2.
Correction of sagittal index
Sagittal index Group A Group B
Preop 25.4 26.1
Postop 11 16.5
Correction 14.4(56.7%) 9.6(36.8%)
Last F/U 16 20.2
Loss of correction 5.0(34.7%) 3.7(38.5%)
Table 3.
Correction of anterior height of body
Ant. Height of Body (%) Goup A Group B
Preop 55.6 56.7
Postop 85.7 77.1
Correction 30.1(54.1%) 20.4(36.0%)
Last F/U 73.8 72.3
Loss of correction 11.9(39.5%) 4.8(23.5%)
Table 4.
Correction of disc height
Height of Disc (%) Goup A Group B
Preop 83.3 85.8
Postop 96.5 95.7
Correction 13.2(15.8%) 9.9(11.5%)
Last F/U 89.5 90.1
Loss of correction 7.0(53.0%) 5.6(56.6%)
Table 5.
Encroachment of spinal canal
  Group A Group B
Preop 43.70% 39.40%
Postop 25.40% 30.50%
Clearance 18.30% 8.90%
Table 6.
Neurological recovery
Frankel Group A Goup B
Classification Preop Postop Preop Postop
A 1 1 1 1
B 3 2 1 1
C 2 2 4 3
D 2 2 3 3
E 17 18 17 18
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