What is the prevalence and distribution of narrow dysplastic and fully corticalized pedicles in Asian adolescent idiopathic scoliosis patients with major main thoracic curves? A computed tomography (CT) scan analysis of 6494 pedicles

• Published in: The spine journal 2023-07
• Main Authors: Chiu, Chee Kidd, Wang, Wee Jieh, Lee, Yu Jie, Chung, Weng Hong, Chan, Chris Yin Wei, Kwan, Mun Keong
• Format: Article
• Language: English
• ISSN: 1878-1632
• DOI: 10.1016/j.spinee.2023.07.006

Patients with adolescent idiopathic scoliosis (AIS) have higher prevalence of abnormal or dysplastic pedicles. To investigate the prevalence and distribution of narrow dysplastic and fully corticalized pedicles in Asian AIS patients with major main thoracic curves. Retrospective study PATIENT SAMPLE: A total of 6494 pedicles in 191 patients were measured and evaluated. The primary outcomes measures were the pedicle width measurements (total transverse pedicle width, transverse cancellous width, total transverse cortical width) and classification of pedicles. Demographic data (age, gender, height, weight, body mass index), proximal thoracic Cobb angle, main thoracic Cobb angle and lumbar Cobb angle were also obtained. AIS patients with major (largest Cobb angle) main thoracic curves and had computed tomography (CT) scans prior to corrective spine surgery were reviewed. The pedicles were classified as Grade A: cancellous channel >4 mm; Grade B: cancellous channel 2 to 4 mm; Grade C: cancellous channel 4 mm; Grade D: corticalized pedicle ≤4 mm. Grades B, C and D were dysplastic pedicles while grades C and D were narrow dysplastic pedicles. The prevalence of dysplastic pedicles (grades B, C and D) was 61.7%. There were 22.6% narrow dysplastic pedicles (grades C and D) and 4.1% fully corticalized pedicles (grade D). In the thoracolumbar region, there was a sharp transition from larger and less dysplastic pedicles at T11 and T12 to narrower and more dysplastic pedicles at L1 and L2 (narrow dysplastic pedicles at T11: 3.1%, T12: 3.1%, L1: 39.8% and L2: 23.6%). Higher prevalence of narrow dysplastic pedicles was located at right T3-T5 (71.2-83.7%) and left T7-T9 (51.3-61.2%). Higher prevalence of fully corticalized pedicles were located at right T3-T5 (20.9-34.0%) and left T7-T8 (11.0-12.0%). These were the concave pedicles of proximal thoracic and main thoracic curves. There were 95.9% pedicles (grades A, B and C) with cancellous channels which can allow pedicle screw fixation and only 4.1% fully corticalized pedicles (grade D) that require an alternative method of fixation. For grade C pedicles (18.5%), pedicle screw can still be attempted with caution. Precautions should also be observed at the L1 and L2 region as the was a transition to narrower pedicles.