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Abstract
Objectives
We wanted to analyze the frequency of instrument breakage and the long term reduction loss for patients who received pedicle screw fixation for thoracolumbar fractures. Summary of the Literature Review: A pedicle screw fixation system for thoracolumbar fractures has become popular since the late 1980s, but it is difficult to find articles mentioning its mid and long term results.
Materials and Methods
Twenty-seven patients those received pedicle screw fixation for thoracolumbar fractures and dislocations and who were followed up more than 5 years were included. The average follow-up period was 139.0 months. We compared the anterior column height, the kyphotic angle and the local kyphotic angle on serial radiographs, and we measured the changes of the intervertebral disc height and the changes of the angle between screws. We also investigated the breakage and loosening of instruments.
Results
The breakage of screws was observed in 11 cases (40.7%) and it had a statistical correlation with the loss of the lower intervertebral disc height and the loss of angles between the screws. During the follow-up, the kyphotic angle, the upper and lower disc height and the interscrew angle were decreased over time, whereas the anterior column height and wedge angle of the vertebra were maintained after the operation. There was no statistical correlation between the breakage of instruments and the degree of lower back pain.
Conclusions
On the mid and long-term follow-up of the patients who were treated by pedicle screws for thoracolumbar fractures, the correction of the kyphotic angle was lost over time and breakage of screws may eventually occur. The loss of the kyphotic angle was mainly due to the continuous loss of the intervertebral disc height.
REFERENCES
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Fig. 3. (A)
Preoperative radiograph shows burst fracture of L2 vertebra. (B) Immediate postoperative radiograph shows a good correction of kyphosis by posterior instrumented fusion. (C) On postoperative 6 year radiograph, decrease of upper and lower disc height and breakage of lower pedicle screws.
Fig. 4. (A)
Changes of anterior body height of fractured vertebra (B) Changes of kyphotic angle of fractured vertebra (C) Changes of wedge angle of fractured vertebra (D) Changes of upper disc height of fractured vertebra (E) Changes of lower disc height of fractured vertebra (F) Changes of interpedicular angle of fractured vertebra. Total : whole patients, None: patients without screw breakage, Failure: patients with pedicle screw breakage.
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