J Korean Soc Spine Surg.  2002 Jun;9(2):98-105.

Determination of Distal Fusion Level with Segmental Pedicle Screw Fixation in Single Thoracic Idiopathic Scoliosis

• Suk SI
• Kim JH
• Lee SM
• Chung ER
• Nah KH
• Lee JH
• Kim SS
• Park SC
• Chung RY
• Won SW

Abstract

STUDY DESIGN: Retrospective study.
OBJECTIVES
To determine the exact distal fusion level in the treatment of single thoracic idiopathic scoliosis (King III and IV) with segmental pedicle screw fixation and rod rotation. SUMMARY OF LITERATURE REVIEW: Pedicle screw fixation effectively shortens the distal fusion extent by improved 3-D deformity correction. However, the selection of distal fusion extent remains controversial in single thoracic idiopathic scoliosis. MATERIAL AND METHODS: Forty-two single thoracic adolescent idiopathic scoliosis patients subject to segmental pedicle screw fixation and rod rotation with minimum follow-up of 2 years (2-6 years) were analyzed. The patients were grouped according to the distal fusion level with reference to the standing neutral vertebra (NV) for comparison of deformity correction, radiological and clinical spinal balance using standing radiographs. Distal fusion down to NV +1 was in 9 patients, NV in 5, NV-1 in 9, NV-2 in 12 and NV-3 in 7 patients respectively.
RESULTS
Preoperative 50+/-11 degrees of thoracic deformity was corrected to 13+/-5 degrees showing 74% of curve correction. Preoperative 23+/-7 degrees of lumbar deformity was corrected to 2+/-8 degrees showing 93% of curve correction. Postoperative adding on deformity was obtained in 14 patients. Significant difference was found not by King classification but by distal fusion level: significantly higher chance of unsatisfactory results from not going to the NV-1 (p=0.001).
CONCLUSIONS
In correction of single thoracic idiopathic scoliosis with segmental pedicle screw fixation, the curve should be fused to NV-1 saving one or more motion segments when compared to the fusion to the stable vertebra.

Keyword

Adolescent idiopathic scoliosis; Single thoracic curve; Distal fusion level; Pedicle screw fixation; Rod rotation

MeSH Terms

Adolescent
Classification
Congenital Abnormalities
Follow-Up Studies
Humans
Retrospective Studies
Scoliosis*
Spine

Figure

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  Fig. 1-A. Preoperative standing anteroposterior radiograph of a 15.8 year old female with 50。 thoracic and 32。 lumbar fractional curve. As determined by the spinous process and pedicle shadows, the neutral vertebrae was L1. Fig. 1-B. Preoperative standing lateral radiograph. Fig. 1-C. Anteroposterior radiograph taken 3.5 years after surgery. The distal fusion was down to neutral vertebra(NV). The thoracic curve is corrected to 10。 with 9。 lumbar fractional curve and balanced spine. Fig. 1-D. Lateral radiograph taken 3.5 years after surgery.

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  Fig. 2-A. Preoperative standing anteroposterior radiograph of a 12.4 year old female with 58。 thoracic and 30。 lumbar fractional curve. As determined by the spinous process and pedicle shadows, the neutral vertebrae was L3. Fig. 2-B. Preoperative standing lateral radiograph. The thoracic spine was hypokyphotic, 4。 of kyphosis. Fig. 2-C. Anteroposterior radiograph taken 4 years after surgery. The distal fusion was down to NV-1 (one level proximal to neutral vertebra). The thoracic curve is corrected to 3。 with 29。 lumbar fractional curve and balanced spine. Fig. 2-D. Lateral radiograph taken 4 years after surgery. The thoracic kyphosis was improved to 25。.

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  Fig. 3-A. Preoperative standing anteroposterior radiograph of a 14.8 year old female with 51。 thoracic and 21。 lumbar fractional curve. As determined by the spinous process and pedicle shadows, the neutral vertebrae was L3. Fig. 3-B. Preoperative standing lateral radiograph. Fig. 3-C. Anteroposterior radiograph taken 2 weeks after surgery. The distal fusion was down to NV-2 (two level proximal to neutral vertebra). The thoracic curve was corrected to 14。 with 2。 lumbar fractional curve and balanced spine. Fig. 3-D. Anteroposterior radiograph taken 3 years after surgery. The lumbar fractional curve shows reversal, resulting in extension of the index thoracic curve into the lumbar segments through adding on. Fig. 3-E. Lateral radiograph taken 3 years after surgery.

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