Zonal differences in risk and pattern of pedicle screw perforations in adolescent idiopathic scoliosis (AIS): a computerized tomography (CT) review of 1986 screws

• Published in: European spine journal Vol. 27; no. 2; pp. 340 - 349
• Main Authors: Chan, C. Y. W., Kwan, M. K.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.02.2018; Springer Nature B.V
• Subjects: Adolescent; Computed tomography; Female; Humans; Male; Medicine; Medicine & Public Health; Neurosurgery; Original Article; Pedicle Screws - adverse effects; Postoperative Complications - diagnostic imaging; Postoperative Complications - etiology; Retrospective Studies; Risk Assessment - methods; Scoliosis; Scoliosis - surgery; Spinal Fusion - adverse effects; Spinal Fusion - instrumentation; Spinal Fusion - methods; Spinal Injuries - diagnostic imaging; Spinal Injuries - etiology; Spine; Surgical Orthopedics; Thoracic Vertebrae - diagnostic imaging; Thoracic Vertebrae - surgery; Thorax; Tomography, X-Ray Computed; Vertebrae; Young Adult; Pedicle screw; Computed tomography; Perforation; Adolescent idiopathic scoliosis
• ISSN: 0940-6719; 1432-0932
• DOI: 10.1007/s00586-017-5350-x

Purpose To evaluate the zonal differences in risk and pattern of pedicle screw perforations in adolescent idiopathic scoliosis (AIS) patients. Methods The scoliosis curves were divided into eight zones. CT scans were used to assess perforations: Grade 0, Grade 1(< 2 mm), Grade 2(2–4 mm) and Grade 3(> 4 mm). Anterior perforations were classified into Grade 0, Grade 1(< 4 mm), Grade 2(4–6 mm) and Grade 3(> 6 mm). Grade 2 and 3 (except lateral grade 2 and 3 perforation over thoracic vertebrae) were considered as ‘critical perforations’. Results 1986 screws in 137 patients were analyzed. The overall perforation rate was 8.4% after exclusion of the lateral perforation. The highest medial perforation rate was at the transitional proximal thoracic (PT)/main thoracic (MT) zone (6.9%), followed by concave lumbar (6.7%) and convex main thoracic (MT) zone (6.1%). The overall critical medial perforation rate was 0.9%. 33.3% occurred at convex MT and 22.2% occurred at transitional PT/MT zone. There were 39 anterior perforations (overall perforation rate of 2.0%). 43.6% occurred at transitional PT/MT zone, whereas 23.1% occurred at concave PT zone. The overall critical anterior perforation rate was 0.6%. 5/12 (41.7%) critical perforations occurred at concave PT zone, whereas four perforations occurred at the transitional PT/MT zone. There were only two symptomatic left medial grade 2 perforations (0.1%) resulting radiculopathy, occurring at the transitional main thoracic (MT)/Lumbar (L) zone. Conclusion Overall pedicle perforation rate was 8.4%. Highest rate of critical medial perforation was at the convex MT zone and the transitional PT/MT zone, whereas highest rate of critical anterior perforation was at the concave PT zone and the transitional PT/MT zone. The rate of symptomatic perforations was 0.1%.