J Korean Soc Spine Surg.  2009 Sep;16(3):160-166. 10.4184/jkss.2009.16.3.160.

The Effect of Vertebral Wedge Angle to the Change of Kyphotic Angle by the Posterior Instrumentation Method in Thoracolumbar Spine Fracture

• Kim SK
• Kim MH
• Lee SC
• Min SH
• Lee JW

• KMID: 2003109
• DOI: http://doi.org/10.4184/jkss.2009.16.3.160

Abstract

STUDY DESIGN: Retrospective study
OBJECTIVES
To examine the effect of transpedicular screw fixation on fractured vertebrae about the vertebral wedge angle (VWA) after posterior instrumentation of the thoracolumbar fracture, determine the effect of reduced VWA on the change in the Kyphotic angle (KA), and minimize loss of reduction of KA. SUMMARY OF THE LITERATURE REVIEW: Maintenance of the KA of a thoracolumbar fracture after surgery is important for the radiologic and functional outcome.
MATERIALS AND METHODS
Forty patients, who had undergone posterior instrumentation in a thoracolumbar fracture between February 2006 and February 2008 and followed-up for more than one year, were enrolled in this study. The patients were divided into two groups according to transpedicular screw fixation (Group A) or not (Group B) including fractured vertebrae. The evaluation was performed by measuring the changes in the KA and VWA taken after the injury, immediate after surgery and 1 year after surgery.
RESULTS
There was correlation between groups A (transpedicular screw fixation on fractured vertebrae) and B (no transpedicular screw fixation on the fractured vertebrae) regarding the correction of the VWA and the loss of correction KA, (p<0.05).
CONCLUSIONS
Reduction of the VWA is an important factor for preventing reduction loss of the KA, and transpedicular screw fixation including fractured vertebrae would help reduce the VWA. Therefore, the operator must pay attention to the increase in VWA to maintain the KA through short segment transpedicular screw fixation including fractured vertebrae.

Keyword

Thoracolumbar spine; Fracture; Transpedicular screw fixation; Vertebral wedge angle; Kyphotic angle

MeSH Terms

Humans
Retrospective Studies
Spine

Figure

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  Fig. 1. Schematic diagram of geometric parameters measured on a lateral radiograph. KA: Kyphotic angle, VWA: Vertebral wedge angle, UIVA: Upper intervertebral angle, LIVA: Lower intervertebral angle

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  Fig. 2. Change of KA & VWA over time (screw fixation including a fractured vertebra) The patient was 24 years old female. Fracture type was Flexion-Distraction. Spinous process of L2 spine was bisected. Transpedicular fixation including a fractured vertebra was done. KA and VWA was initial 7°, 16° and immediate postoperation -22°, 2°, last followup -20°, 2°, After implant removal -19°, 2°. Initial reduction of VWA was 14°. So, reduction loss of KA and VWA (2°, 0°) was minimal. Reduction loss KA and VWA (3°, 0°) after implant removal was minimal, too. (A) Preoperative lateral radiography (B) immediate postoperative lateral radiography (C) Followup lateral radiography after 15 months (D) Followup lateral radiography after implant removal.

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  Fig. 3. Change of KA & VWA over time (screw fixation not including a fractured vertebra) The patient was 54 years old male. Fracture type was Flexion-Distraction. Transpedicular fixation not including a fractured vertebra was done. KA and VWA was initial 34°, 27°and immediate postoperation 15°, 7°, last followup 20°, 17°. Initial reduction of VWA was 20°. Reduction loss of KA and VWA (5°, 10°) was progressed. (A) Preoperative lateral radiography (B) immediate postoperative lateral radiography (C) Followup lateral radiography after 27 months.

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  Fig. 4. Change of KA & VWA over time (screw fixation including a fractured vertebra) The patient was 69 years old male. Fracture type was Flexion-Distraction. Transpedicular fixation including a fractured vertebra was done. KA and VWA was initial 32°, 26°and immediate postoperation 21°, 20°, last followup 30°, 25°. Initial reduction of VWA was 6°. So, reduction loss of KA and VWA (9°, 5°) was progressed. (A) Preoperative lateral radiography (B) immediate postoperative lateral radiography (C) Followup lateral radiography after 23 months.

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