Elsevier

Spine Deformity

Volume 1, Issue 1, January 2013, Pages 46-50
Spine Deformity

Case Series
Maintenance of Thoracic Kyphosis in the 3D Correction of Thoracic Adolescent Idiopathic Scoliosis Using Direct Vertebral Derotation

https://doi.org/10.1016/j.jspd.2012.06.001Get rights and content

Abstract

Objectives

Through a review of prospectively collected data, we sought to analyze the outcomes related to 3-dimensional correction of adolescent idiopathic scoliosis (AIS) after posterior spinal fusion (PSF) and instrumentation using an aggressive combination of correction strategies.

Background Summary

New techniques have been used to address sagittal plane deformity while maximizing coronal and axial correction, including Ponte osteotomy, differential rod over-contouring, and direct vertebral rotation with uniplanar screws.

Methods

This is a consecutive single-center series of AIS patients with thoracic curves (Lenke 1 and 2) with 2-year follow-up who underwent PSF and instrumentation with the use of the following correction strategies: segmental uniplanar screws, ultra high-strength 5.5 mm steel rods, aggressive differential rod contouring, periapical Ponte osteotomies, and segmental direct vertebral derotation. Scoliosis Research Society (SRS)-22, radiographic and clinical parameters were evaluated at preoperative and 2-year time points.

Results

Twenty-six patients were included (mean age 13.6 ± 1.5 years). Preoperative thoracic Cobb measured 52 ± 9°, which improved to 17 ± 4° at 2-year follow-up, resulting in 68 ± 9% correction. The average thoracic kyphosis from T5-T12 did not significantly change (21 ± 10° to 22 ± 5° at 2 years); however, in patients with kyphosis less than 20° preoperatively (avg. 13 ± 5°) kyphosis increased significantly at 2-year follow-up (avg. 20 ± 4°, p<.05). Preoperatively, axial rotation was more than 13° in 21 of 26 cases. At 2-year follow-up, axial rotation remained more than 13° in 4 of 26 cases (p<.01). Rib hump prominence was 17 ± 5° preoperatively, which improved significantly to 10 ± 4° at 2-year follow-up (p<.05). Postoperative SRS domain scores significantly improved in pain (4.3 to 4.7), self-image (3.7 to 4.3), and satisfaction (3.3 to 4.6) (p<.05).

Conclusion

A high degree of coronal correction can be achieved in association with vertebral derotation without sacrificing sagittal plane alignment. High-strength rods aggressively bent to create kyphosis allow both restoration of kyphosis and axial plane derotation in thoracic idiopathic scoliosis.

Introduction

In the past several years, excellent coronal correction has been reported using segmental pedicle screw fixation in the treatment of adolescent idiopathic scoliosis (AIS) [1], [2], [3], [4], [5], [6], [7], [8], [9]. However, many of these same studies have demonstrated an associated loss of thoracic kyphosis. One of the goals of AIS treatment is to maximize coronal and axial plane correction while restoring thoracic kyphosis. Recently, uniplanar screws were developed to provide the benefits seen with polyaxial screws in the sagittal plane in maintaining thoracic kyphosis, while maintaining the advantages of a fixed angle screw in the coronal and axial planes. The purpose of this study was to analyze the 3-dimensional correction after posterior instrumentation and fusion with the combined use of uniplanar screws, Ponte osteotomy, differential rod contour, and direct vertebral rotation.

Section snippets

Materials and Methods

A retrospective review of prospectively collected data of a single center from a larger multi-center study was conducted. Patients with AIS, Lenke type 1 or type 2 curves who underwent posterior spinal fusion and instrumentation at a single institution from 2006 to 2008 by a single surgeon were included. Uniplanar screws, ultra high-strength 5.5 mm steel rods, Ponte osteotomies, differential rod contouring, and direct vertebral rotation were used in all cases. Patients who underwent an anterior

Results

There were 26 patients (23 female, 3 male) with a mean age at the time of surgery of 13.6±1.5 years (11-17 years). There were 16 Lenke type 1 curves and 10 type 2 curves. The lumbar modifier was type A in 11 patients, type B in 6, and type C in 9. Preoperatively, 21 out of 26 patients had a sagittal profile in the “normal” range (T5–T12 10°-40°), 5 patients were hypokyphotic (T5–T12 <10°), and none were hyperkyphotic (T5–T12 >40°), according to the Lenke Classification system.

The mean operative

Discussion

The achievement and maintenance of high degrees of coronal correction in the surgical treatment of AIS using segmental pedicle screw fixation is well documented in the literature, dating back to the work of Suk et al. in 1995, which described the efficacy of pedicle screw fixation compared with all hook constructs [1]. Since that time, numerous studies have reported on the effectiveness of pedicle screws in achieving coronal correction [1], [2], [3], [4], [5], [6], [7], [8]. Lehman et al., for

Conclusion

This study shows that excellent coronal and axial correction can be achieved without sacrificing thoracic kyphosis. Several strategies were employed: multi-level Ponte osteotomies, differential rod over-contouring, uniplanar screws and ultra-strength 5.5 mm steel rods. This combination offers a solution to the commonly seen problem of induced hypokyphosis associated with pedicle screw constructs and direct vertebral rotation used in the correction of thoracic AIS.

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Author disclosures: DS (none); BY (consulting for K2M, Synthes, Ellipse; research support to institution from KCI, DePuy, K2M, Ellipse; speaking fees from DePuy; royalties from Orthopediatrics); JHC (none); VVU (none); TPB (none); CEB (none); PON (consulting for DePuy and Stanford University; expert testimony; research support to instituion from NIH, OREF, POSNA, SRS, Harms Study Group Foundation, DePuy, Axial Biotech, and Biospace Med/EOS Imaging; speaking frees from DePuy; patents with DePuy; royalties from DePuy and Thieme Publishing; development of educational presentations from DePuy; stock from Nuvasive).

This work is supported in part by a grant from JJKK Medical Company, a Division of DePuy Spine, Japan and in part by a grant to the Harms Study Group Foundation from Depuy Spine.

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