J Korean Orthop Assoc.  2019 Apr;54(2):141-149. 10.4055/jkoa.2019.54.2.141.

Correction of Single Thoracic Adolescent Idiopathic Scoliosis Using Pedicle Screw Instrumentation: Comparison of Stainless Steel to Titanium Alloy Instruments

• Kim SS
• Lim DJ
• Kim JH
• Choi BW
• Kim HY
• Lee JS

• KMID: 2444779
• DOI: http://doi.org/10.4055/jkoa.2019.54.2.141

Abstract

PURPOSE
To compare the results of two different instruments made of stainless steel and titanium alloy for correction of single thoracic adolescent idiopathic scoliosis (AIS) using pedicle screw instrumentation.
MATERIALS AND METHODS
A total of 141 patients with single thoracic AIS treated with pedicle screw instrumentation and selective thoracic fusion were retrospectively reviewed after a follow-up of 2 years. The patients had a main thoracic curve of 40° to 75° and were divided into two groups based on instrument materials; S group (stainless steel, n=90) and T group (titanium alloy, n=51). The diameter of the stainless steel rod used was 7.0 mm while that of the titanium alloy rod was 6.35 mm or 6.0 mm. Standing long-cassette radiographic measurements including various coronal and sagittal parameters for the preoperative, early postoperative and 2-year postoperative follow-up were analyzed. There were no significant differences in the preoperative curve characteristics between the two groups.
RESULTS
In the S group, the preoperative main thoracic curve of 51.3°±8.4° was improved to 19.0°±7.6° (63.1% correction) and the lumbar curve of 32.3°±8.4° spontaneously decreased to 12.7°±8.2° (62.9% correction) at 2 years postoperatively. In the T group, the preoperative main thoracic curve of 49.5°±8.4° and the lumbar curve of 30.3°±8.9° was improved to 18.8°±7.4° (62.2% correction) and 11.3°±5.4° (63.3% correction), respectively. The corrections of coronal curves were not statistically different between the two groups (p>0.05). The thoracic kyphosis was changed from 16.8°±8.5° to 24.3°±6.1° in the S group and from 19.6°±11.2° to 26.6°±8.5° in the T group. There were no significant differences in the changes of sagittal curves, coronal and sagittal balances at the 2-year follow-up and the number of fused segments and used screws between the two groups (p>0.05).
CONCLUSION
When conducting surgery for single thoracic AIS using pedicles screw instrumentation, two different instruments made of stainless steel and titanium alloy showed similar corrections for coronal and sagittal curves.

Keyword

scoliosis; adolescent; pedicle screws; stainless steel; titanium

MeSH Terms

Adolescent*
Alloys*
Follow-Up Studies
Humans
Kyphosis
Pedicle Screws*
Retrospective Studies
Scoliosis*
Stainless Steel*
Steel
Titanium*
Alloys
Stainless Steel
Steel
Titanium

Figure

• 

  Figure 1 Thirteen-year-old girl with single thoracic curve. (A) Preoperative anterolateral radiograph showed the main thoracic curve of 51° and the lumbar curve of 33°. (B) Preoperative lateral radiography. (C, D) Anteroposterior and lateral radiographs taken 2 months after surgery (PO 2M). The patient was treated with selective thoracic fusion from T4 to L1 using pedicle screw instruments made of stainless steel. The main thoracic curve was corrected to 13° and the lumbar curve was spontaneously corrected to 11°. (E, F) Anteroposterior and lateral radiographs taken 2 years after surgery (PO 2Y). Coronal and sagittal alignments were well maintained during the follow-up.

• 

  Figure 2 Fourteen-year-old girl with single thoracic curve. (A) Preoperative anterolateral radiograph showed the main thoracic curve of 48° and the lumbar curve of 24°. (B) Preoperative lateral radiography. (C, D) Anteroposterior and lateral radiographs taken 2 months after surgery (PO 2M). The patient was treated with selective thoracic fusion from T5 to L1 using pedicle screw instruments made of titanium alloy. The main thoracic curve was corrected to 15° and the lumbar curve was spontaneously corrected to 5°. (E, F) Anteroposterior and lateral radiographs taken 2 years after surgery (PO 2Y). Coronal and sagittal alignments were well maintained during the follow-up.

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