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