Prevalence, distribution, and surgical relevance of abnormal pedicles in spines with adolescent idiopathic scoliosis vs. no deformity

A CT-based study

Vishal Sarwahi, Etan P. Sugarman, Adam L. Wollowick, Terry D. Amaral, Yungtai Lo, Beverly Ann Thornhill

Research output: Contribution to journalArticle

19 Citations (Scopus)

Abstract

Background: A thorough understanding of pedicle morphology is necessary for pedicle screw placement. Previous studies classifying pedicle morphology, to our knowledge, have neither discussed the range of abnormal morphology nor correlated patient or curve characteristics with abnormal morphology to identify at-risk pedicles. Methods: With the use of computed tomography (CT) images, we analyzed a total of 6116 pedicles from ninety-five patients without spinal deformity (forty-two females and fifty-three males) and ninety-one patients with adolescent idiopathic scoliosis (AIS) (sixty-eight females and twenty-three males). Pedicle morphology was classified as: Type A, a cancellous channel of >4 mm; Type B, a cancellous channel of 2 to 4 mm; Type C, a cortical channel of ≥2 mm; or Type D, a cortical or cancellous channel of <2 mm. Types B, C, and D were defined as abnormal. Patient demographic data and pedicle distribution were assessed for prevalence and likelihood of abnormal pedicle morphology. Postoperative CT images from fifty-nine patients with AIS were used to assess screw placement. Results: There was a significantly higher rate of abnormal pedicles in patients with AIS (p = 0.001). More abnormal pedicles were located in the thoracic spine compared with the lumbar spine both in patients without deformity (13.3% versus 2.0%) and patients with AIS (31.9% versus 2.4%). Significantly more abnormal pedicles were located on the concavity (p < 0.001), within the periapical region (p = 0.02), and on the apex of the curve (p = 0.03). Three times as many pedicle screws were misplaced in abnormal pedicles compared with normal pedicles (21% versus 7%). Conclusions: Our study found a significantly higher prevalence of abnormal pedicles in the patients with AIS. Of the abnormal pedicles in these patients, most were in the thoracic spine, on the concave side, and in the periapical and apical regions. Clinical Relevance: Knowledge of abnormal pedicles may enable surgeons to anticipate and plan for difficult screw placement and further decrease risk to the patient.

Original languageEnglish (US)
JournalJournal of Bone and Joint Surgery - American Volume
Volume96
Issue number11
DOIs
StatePublished - Jun 4 2014

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Scoliosis
Spine
Tomography
Thorax
Demography

ASJC Scopus subject areas

  • Surgery
  • Orthopedics and Sports Medicine

Cite this

Prevalence, distribution, and surgical relevance of abnormal pedicles in spines with adolescent idiopathic scoliosis vs. no deformity : A CT-based study. / Sarwahi, Vishal; Sugarman, Etan P.; Wollowick, Adam L.; Amaral, Terry D.; Lo, Yungtai; Thornhill, Beverly Ann.

In: Journal of Bone and Joint Surgery - American Volume, Vol. 96, No. 11, 04.06.2014.

Research output: Contribution to journalArticle

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title = "Prevalence, distribution, and surgical relevance of abnormal pedicles in spines with adolescent idiopathic scoliosis vs. no deformity: A CT-based study",
abstract = "Background: A thorough understanding of pedicle morphology is necessary for pedicle screw placement. Previous studies classifying pedicle morphology, to our knowledge, have neither discussed the range of abnormal morphology nor correlated patient or curve characteristics with abnormal morphology to identify at-risk pedicles. Methods: With the use of computed tomography (CT) images, we analyzed a total of 6116 pedicles from ninety-five patients without spinal deformity (forty-two females and fifty-three males) and ninety-one patients with adolescent idiopathic scoliosis (AIS) (sixty-eight females and twenty-three males). Pedicle morphology was classified as: Type A, a cancellous channel of >4 mm; Type B, a cancellous channel of 2 to 4 mm; Type C, a cortical channel of ≥2 mm; or Type D, a cortical or cancellous channel of <2 mm. Types B, C, and D were defined as abnormal. Patient demographic data and pedicle distribution were assessed for prevalence and likelihood of abnormal pedicle morphology. Postoperative CT images from fifty-nine patients with AIS were used to assess screw placement. Results: There was a significantly higher rate of abnormal pedicles in patients with AIS (p = 0.001). More abnormal pedicles were located in the thoracic spine compared with the lumbar spine both in patients without deformity (13.3{\%} versus 2.0{\%}) and patients with AIS (31.9{\%} versus 2.4{\%}). Significantly more abnormal pedicles were located on the concavity (p < 0.001), within the periapical region (p = 0.02), and on the apex of the curve (p = 0.03). Three times as many pedicle screws were misplaced in abnormal pedicles compared with normal pedicles (21{\%} versus 7{\%}). Conclusions: Our study found a significantly higher prevalence of abnormal pedicles in the patients with AIS. Of the abnormal pedicles in these patients, most were in the thoracic spine, on the concave side, and in the periapical and apical regions. Clinical Relevance: Knowledge of abnormal pedicles may enable surgeons to anticipate and plan for difficult screw placement and further decrease risk to the patient.",
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