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Definition of safe zone in vertebral body in relation to anterior instrumentation
Rosa M Egea-Gámez1, James Wilson-MacDonald2, David Murray2
1Paediatric Orthopaedic Service, Hospital Infantil Universitario Niño Jesús, Menéndez Pelayo 65, 28009 JCR, Madrid, Spain. rosamaria.egea@salud.madrid.org.
Insights
This study defines safe zones for anterior instrumentation in scoliosis surgery by analyzing great vessel proximity to the spine. Understanding these spinal safe zones is crucial for improving surgical safety and outcomes.
Area of Science:
- Spinal surgery
- Pediatric orthopedics
- Surgical anatomy
Background:
- Anterior instrumentation in scoliosis surgery requires precise placement to avoid great vessel injury.
- Determining the "safe zone" for device placement relative to the aorta and vena cava is critical.
Purpose of the Study:
- To define the "safe zone" for anterior instrumentation in scoliosis surgery.
- To assess the relationship between the great vessels and the spine (T4-L4).
Main Methods:
- 34 children with posterior idiopathic scoliosis underwent preoperative scan analysis.
- A coordinate system was used to define the safe zone right (SZR) and safe zone left (SZL) angles relative to the great vessels.
- Correlation analysis was performed between curve laterality and safe zone dimensions.
Main Results:
- Mean SZL ranged from 155.7°-180° (T4) to 104.3°-180° (L4).
- Mean SZR ranged from 0-110.7° (T4) to 0-76.18° (L4).
- Significant correlations were found between curve side and SZL (T4-L2) and SZR (T7-L2).
Conclusions:
- Safe zones are predominantly on the right from T4-T11 and more lateral/smaller from T12-L4.
- Right-sided scoliosis shifts the danger zone posterolaterally; left-sided curves shift it anteromedially.
- Knowledge of these spinal safe zones aids in safer anterior device placement during scoliosis surgery.
Objectives:
We set out to determine the "safe zone" for anterior instrumentation in scoliosis surgery assessing the relationship of the great vessels to the spine.
Methods:
A total of 34 children undergoing posterior idiopathic scoliosis surgery were included in the study between 2010 and 2016. The preoperative scans were assessed to identify the position of the great vessels relative to the spine from T4 to L4. A coordinate system was specifically designed to determine safe zones for device locations. The safe zone right (SZR) was defined as the angle formed between X-axis (0°) and a line connecting the origin and the edge of the aorta and the safe zone left (SZL), the angle between the edge of the aorta to 180°.
Results:
The average age was 14 years, with 30 females (88.2%). Lenke classification, the most common curve was 1BN (20.6%), followed by 1AN, 3C- and 6CN (8.8% each). The Apex was T8 and T9 (29.4 and 23.5% respectively). 58% of the curves were right sided. The mean SZL was from 155.7° to 180° at the T4 level to 104.3°-180° at L4. The mean SZR was from 0 to 110.7° at T4 to 0-76.18° at L4. The side of the curves was correlated at p level with the SZL and SZR. There was a significant correlation in the following levels: from T4 to L2 in the SZL, and from T7 to L2 in the SZR.
Conclusions:
Between T4 and T11, the right side of the vertebrae is safe, and from T12 to L4 the safe zones are more lateral and smaller. In a right-sided scoliosis, the danger zone moves more posterolateral at every level. In a left-sided curve, the danger zone is more anteromedial. Knowledge of these safe zones should allow safer placement of anterior devices.
Level Of Evidence:
Level III.
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