J Korean Soc Spine Surg.  2009 Sep;16(3):177-185. 10.4184/jkss.2009.16.3.177.

Radiologic Analysis of Postoperative Sagittal Plane Correction in Lumbar Degenerative Kyphosis (LDK)

• Kim WJ
• Kang JW
• Yang DS
• Kang SI
• Park KY
• Park JG
• Sung HI
• Choy WS

• KMID: 2003112
• DOI: http://doi.org/10.4184/jkss.2009.16.3.177

Abstract

STUDY DESIGN: This is a retrospective study OBJECTIVES: We radiologically analyzed the correction of the sagittal imbalance and the proximal fusion level to prevent correction loss and the usefulness of iliac screws in LDK. SUMMARY OF THE LITERATURE REVIEW: Complications can be encountered during fixation and fusion as most of the LDK patients are aged, and the osteoporosis that causes fixation loss is known to affect the loss of correction.
MATERIALS AND METHODS
We analyzed the cause of correction loss among 35 patients who underwent surgery and who were followed up for at least 1 year. All the patients had performed gait analysis before operation. The operative techniques were pedicle subtraction osteotomy and fixation to S1. For analyzing causes of correction loss, we analyzed the degrees of lumbar lordosis for the sagittal correction and the degrees of the preoperative thoracolumbar kyphosis for the proximal fusion range. For analyzing the usefulness of iliac screws, the subjects were divided into two groups: 1) the -iliac screw (23cases) group for the patients who were fixed without iliac screws and 2) the +iliac screw (12cases) group for the patients who were fixed with iliac screws.
RESULTS
There were no patients who had marked anterior pelvic tilt. It is important to correct the lumbar lordosis over 20degrees compared with the preoperative thoracic kyphosis. There are 10 cases of preoperative thoracolumbar kyphosis > or = 10degrees and 25 cases of preoperative thoracolumbar kyphosis < 10degrees of the total 35 cases. Among 10 cases of preoperative thoracolumbar kyphosis > or = 10degrees, 4 cases that were fixed to T10 had no sagittal correction loss, and 2 of the 6 cases that were fixed to T11 or T12 had sagittal correction loss. For the 25 cases of preoperative thoracolumbar kyphosis < 10degrees, 5 cases that were fixed to T10 had no sagittal correction loss and 1 of the 20 cases that were fixed to T11 or T12 had sagittal correction loss (p<0.05). 6 cases (26%) in the -iliac screw group (23 cases total) and 1 case (8%) in the +iliac screw (12 cases total) showed sagittal correction loss (p<0.05).
CONCLUSIONS
It is important to make the postoperative lumbar lordosis over 20degrees compared with the preoperative thoracic kyphosis for correcting sagittal imbalance, to decide on the proximal fixation level according to the preoperative thoracolumbar kyphosis and to fix with iliac screws.

Keyword

Lumbar degenerative kyphosis; Iliac screw; Sagittal plane correction loss

MeSH Terms

Aged
Animals
Gait
Humans
Kyphosis
Lordosis
Osteoporosis
Osteotomy
Retrospective Studies

Figure

• 

  Fig. 1. A 66-year old woman with Lumbar degenerative kyphosis. (A) Preoperative thoracolumbar kyphosis 25°(B) Postoperative sagittal balance after spinal fusion from T12 to S1 and L3 PSO (C) Sagittal balance loss due to proximal screw loosening after postoperative 4 years later. PSO, Pedicle subtraction osteotomy

• 

  Fig. 2. A 62-year old woman with Lumbar degenerative kyphosis. (A) Preoperative thoracic kyphosis 25°, thoracolumbar kyphosis 25° (B) Proper sagittal balance after spinal fusion from T10 to S1 and L3 PSO. Postoperative lumbar lordosis -45° (C) Maintain proper sagittal balance after 2 years later operation. PSO, Pedicle subtraction osteotomy

• 

  Fig. 3. A 73-year old woman with Lumbar degenerative kyphosis. (A) Preoperative thoracic kyphosis 16°, thoracolumbar kyphosis 14°, lumbar lordosis -7°(B) Proper sagittal balance after spinal fusion from T10 to S1 with iliac screw and L3 PSO. Postoperative lumbar lordosis -45° (C) Maintain proper sagittal balance after 2 years later operation. PSO, Pedicle subtraction osteotomy

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