Abstract

BackgroundPosterior vertebral column resection (PVCR) is an effective alternative for treating rigid and severe spinal deformities. Accurate placement of pedicle screws, especially apically, is crucial. As morphologic evaluations of thoracic pedicles have not provided objective criteria, we propose a thoracic pedicle classification for treating rigid and severe spinal deformities.MethodsA consecutive series of 56 patients with severe and rigid spinal deformities who underwent PVCR at a single institution were reviewed retrospectively. Altogether, 1098 screws were inserted into thoracic pedicles at T2-T12. Based on the inner cortical width of the thoracic pedicles, the patients were divided into four groups: group 1 (0–1.0 mm), group 2 (1.1–2.0 mm), group 3 (2.1–3.0 mm), group 4 (≥3.1 mm). The proportion of screws accurately inserted in thoracic pedicles for each group was calculated. Statistical analysis was also performed regarding types of thoracic pedicles classified by Lenke et al. (SPINE 35:1836-1842, 2010) using a morphological method.ResultsThere were statistically significant differences in the rates of screws inserted in thoracic pedicles between the groups (P < 0.008) except groups 3 and 4 (P > 0.008), which were then combined. The accuracies for the three new groups were 35.05%, 65.34%, and 88.32%, respectively, with statistically significant differences between the groups (P < 0.017). Rates of screws inserted in thoracic pedicles classified by Lenke et al. (SPINE 35:1836-1842, 2010) were 82.31%, 83.40%, 80.00%, and 30.28% for types A, B, C, and D, respectively. There was no statistically significant difference (P > 0.008) between these types except between type D and the other three types (P < 0.008).ConclusionsThe inner cortical width of thoracic pedicles is the sole factor crucial for accurate placement of thoracic pedicle screws. We propose a computed tomography-based classification of the pedicle’s inner cortical width: type I thoracic pedicle: absent channel, inner cortical width of 0–1 mm; type II: presence of a channel of which type IIa has an inner cortical width of 1.1–2.0 mm and type IIb a width of ≥2.1 mm. The proposed classification can help surgeons predict whether screws can be inserted into the thoracic pedicle, thus guiding instrumentation when PVCR is performed.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2474-15-278) contains supplementary material, which is available to authorized users.

Highlights

  • Posterior vertebral column resection (PVCR) is an effective alternative for treating rigid and severe spinal deformities

  • The accuracies of thoracic pedicle screw placement were 35.05%, 65.34%, 86.36%, and 90.16% in groups 1, 2, 3, and 4, respectively

  • We have proposed criteria for establishing a thoracic pedicle classification based on the inner cortical width of thoracic pedicles as determined on computed tomography (CT) scans, and believe these criteria can be of clinical significance

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Summary

Introduction

Posterior vertebral column resection (PVCR) is an effective alternative for treating rigid and severe spinal deformities. As morphologic evaluations of thoracic pedicles have not provided objective criteria, we propose a thoracic pedicle classification for treating rigid and severe spinal deformities. The combined use of posterior vertebral column resection (PVCR) and pedicle instrumentation has allowed greater deformity correction and overall spinal balance than are achieved with conventional approaches. When PVCR is performed to treat severe spinal deformities, the most crucial step is to insert the screw within the pedicle. Most studies focused on the morphology of the pedicles [2,3,4,5], which gives little help to surgeons for predicting the accuracy and guiding the procedure of thoracic pedicle screw placement. There are few studies on the correlation between the diameter of the thoracic pedicle channel and the accuracy of thoracic pedicle screw placement

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