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Steven W. Hwang, Amer F. Samdani, Mark Tantorski, Patrick Cahill, Jason Nydick, Anthony Fine, Randal R. Betz and M. Darryl Antonacci


Several studies have characterized the relationship among postoperative thoracic, lumbar, and pelvic alignment in the sagittal plane. However, little is known of the relationship between postoperative thoracic kyphosis and sagittal cervical alignment in patients with adolescent idiopathic scoliosis (AIS) treated with all pedicle screw constructs. The authors examined this relationship and associated factors.


A prospective database of pediatric patients with AIS undergoing spinal fusion between 2003 and 2005 was reviewed for those who received predominantly pedicle screw constructs for Lenke Type 1 or Type 2 curves. Parameters analyzed on pre- and postoperative radiographs were the fusion levels; cervical, thoracic, and lumbar sagittal balance; and C-2 and C-7 plumb lines.


Preoperatively, 6 (Group A) of the 22 patients included in the study had frank cervical kyphosis (mean angle 13.0°) with mean associated thoracic kyphosis of 27.2° (range 16°–37°). Postoperatively, cervical kyphosis (13.0°) remained in the patients in Group A along with mean thoracic kyphosis of 17.7° (range 4°–26°, p < 0.05). Preoperatively, the remaining 16 of 22 patients had neutral to lordotic cervical alignment (mean −13.8°) with thoracic kyphosis (mean 45°, range 30°–76°). Postoperatively, 8 (Group B) of these 16 patients demonstrated cervical sagittal decompensation (> 5° kyphosis), with 6 showing frank cervical kyphosis (10.5°, p < 0.05). In Group B, the mean postoperative thoracic kyphosis was 25.6° (range 7°–49°, p < 0.05). The other 8 patients (Group C) had mean postoperative thoracic kyphosis of 44.1° (range 32°–65°), and there was no cervical decompensation (p < 0.05).


The sagittal profile of the thoracic spine is related to that of the cervical spine. The surgical treatment of Lenke Type 1 and 2 curves by using all pedicle screw constructs has a significant hypokyphotic effect on thoracic sagittal plane alignment (19 [86%] of 22 patients). If postoperative thoracic kyphosis is excessively decreased (mean 25.6°, p < 0.05), the cervical spine may decompensate into significant kyphosis.

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Steven W. Hwang, Amer F. Samdani, Baron S. Lonner, Michelle C. Marks, Tracey P. Bastrom, Randal R. Betz and Patrick J. Cahill


In the surgical management of adolescent idiopathic scoliosis (AIS), patients are often preoperatively informed that they will gain height as a result of their surgery. However, current estimations conflict significantly and do not have any clinical correlation. The authors developed a formula that would predict postoperative gains in height after deformity correction in AIS.


A large, multicenter, prospective database was retrospectively queried for AIS patients with Lenke Type 1, 2, or 3 curves having undergone posterior spinal fusion alone. A univariate and multivariate analysis was performed to identify which factors contributed significantly to changes in height.


Four hundred forty-seven patients were included in the series. Factors correlating with changes in postoperative height included: upper thoracic curve magnitude, main thoracic curve magnitude, lumbar curve magnitude, T2–12 kyphosis, T5–12 kyphosis, curve flexibility, number of levels fused, presence of Ponte osteotomies, total preoperative coronal Cobb angle, change in coronal curve magnitude, total preoperative sagittal curvature, change in sagittal curvature, and thoracic curve correction.

When combined in a multivariate regression analysis the following variables remained significant: thoracic curve magnitude (p < 0.01), number of levels fused (p < 0.01), change in total sagittal curvature (p < 0.01), and the presence of osteotomies (p = 0.03). The contribution from the thoracic curve magnitude was significantly greater than any of the other parameters identified (R2 = 0.140). Change in height (in cm) = ([thoracic curve magnitude × 0.039] + [number of levels fused × 0.193] − [change in sagittal curvature × 0.033] + [x × 0.375]) − 1.858, where x = 1 if 1 or more osteotomies were performed and x = 0 if no osteotomy was performed.


The authors' results suggest that changes in the coronal plane contribute more significantly to height changes than those in the sagittal plane and approximately 0.39 cm of height gain can be expected for each 10° of coronal curve preoperatively. Unfortunately, a significant fraction of the postoperative height changes cannot be predicted by currently measured parameters.

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Charles E. Mackel, Patrick J. Cahill, Marie Roguski, Amer F. Samdani, Patrick A. Sugrue, Noriaki Kawakami, Peter F. Sturm, Joshua M. Pahys, Randal R. Betz, Ron El-Hawary and Steven W. Hwang


The authors performed a study to identify clinical characteristics of pediatric patients diagnosed with Chiari I malformation and scoliosis associated with a need for spinal fusion after posterior fossa decompression when managing the scoliotic curve.


The authors conducted a multicenter retrospective review of 44 patients, aged 18 years or younger, diagnosed with Chiari I malformation and scoliosis who underwent posterior fossa decompression from 2000 to 2010. The outcome of interest was the need for spinal fusion after decompression.


Overall, 18 patients (40%) underwent posterior fossa decompression alone, and 26 patients (60%) required a spinal fusion after the decompression. The mean Cobb angle at presentation and the proportion of patients with curves > 35° differed between the decompression-only and fusion cohorts (30.7° ± 11.8° vs 52.1° ± 26.3°, p = 0.002; 5 of 18 vs 17 of 26, p = 0.031). An odds ratio of 1.0625 favoring a need for fusion was established for each 1° of increase in Cobb angle (p = 0.012, OR 1.0625, 95% CI 1.0135–1.1138). Among the 14 patients older than 10 years of age with a primary Cobb angle exceeding 35°, 13 (93%) ultimately required fusion. Patients with at least 1 year of follow-up whose curves progressed more 10° after decompression were younger than those without curve progression (6.1 ± 3.0 years vs 13.7 ± 3.2 years, p = 0.001, Mann-Whitney U-test). Left apical thoracic curves constituted a higher proportion of curves in the decompression-only group (8 of 16 vs 1 of 21, p = 0.002).


The need for fusion after posterior fossa decompression reflected the curve severity at clinical presentation. Patients presenting with curves measuring > 35°, as well as those greater than 10 years of age, may be at greater risk for requiring fusion after posterior fossa decompression, while patients less than 10 years of age may require routine monitoring for curve progression. Left apical thoracic curves may have a better response to Chiari malformation decompression.