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Abstract
BackgroundThe application of laminar screws is an alternative fixation for the first thoracic vertebra (T1). This paper is to determine the anatomical characteristics for adequate laminar screw fixation, and present a modified method of sagittal reconstruction of T1 to provide more accurate measurements.MethodsComputed tomography (CT) images of 62 patients (32 males, 30 females) were used for the analysis. The following parameters of the T-1 lamina were measured using Mimics software: lamina length, axis angle, minimal outer cortical width, cancellous width, minimal outer cortical height, cancellous height, and spinous process height. Right or left modified sagittal reconstructions (parallel to right or left screws) were innovatively used for measurement.ResultsThere were no significant differences between the left and right sides for each measurement performed (P > 0.05), but significant differences were detected between males and females (P < 0.05). The mean length of the T1 lamina was 32.8 mm of the T1 minimal outer cortical width was 7.4 mm, and 3.8% of males had a minimal outer cortical width < 5 mm, while 8.6% of females had a minimal outer cortical width < 5 mm. The mean minimal outer cortical height was 10.8 mm, and 1.9% of males had a minimal outer cortical height < 9 mm, while 7.7% of females had a minimal outer cortical height < 9 mm.ConclusionThis study suggests there are no anatomical limitations for T1 laminar screw placement in most people. The modified sagittal reconstruction method described allows for easy and precise measurement to aid in the insertion of laminar screws in T1, and gives good visualization of laminar screw insertion direction.
Highlights
The application of laminar screws is an alternative fixation for the first thoracic vertebra (T1)
Pedicle screws fixation is commonly used for fixation in patients with cervicothoracic junction (CTJ) disease, but it is a challenge for many surgeons
The anatomical structure of First thoracic vertebra (T1) varies by ethnicity and region, and the data may not be generalizable to other populations and explain differences between the results of this study and that of Hu et al [13]
Summary
The application of laminar screws is an alternative fixation for the first thoracic vertebra (T1). There are many fixation options for the surgical treatment of cervicothoracic junction (CTJ) disease, deformity, tumors and spinal canal stenosis occurring in the lower cervical and upper thoracic region. Previous studies have verified that the superior and inferior nerve roots of T1 and T2 are close at their exit, which make them easy to injury during pedicle screws insertion [6]. For these reasons, classical pedicle screw fixation, which is the gold standard for thoracic and lumbar spinal instrumentation, is difficult to perform in this region, especially for T1
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