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Predicting the Outcome of Selective Thoracic Fusion in False Double Major Lumbar “C” Cases With Five- to Twenty-Four-Year Follow-up

Chang, Michael S., MD; Bridwell, Keith H., MD; Lenke, Lawrence G., MD; Cho, Woojin, MD, PhD; Baldus, Christine, RN; Auerbach, Joshua D., MD; Crawford, Charles H. III, MD; O'Shaughnessy, Brian A., MD

doi: 10.1097/BRS.0b013e3181e5e36e
Deformity
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Study Design. Retrospective radiographic and clinical study.

Objective. To examine the long-term outcome of selective thoracic fusion (STF) performed for lumbar “C” modifier curves in adolescent idiopathic scoliosis.

Summary of Background Data. The efficacy of STF in lumbar “C” false double major curves is controversial. We examined the 5- to 24-year outcomes of patients with “C” lumbar curves who underwent STF at a single institution to determine which factors help predict successful outcome.

Methods. Thirty-two patients (age, 14.8 ± 2.0 years) with a lumbar “C” modifier underwent primary STF and had minimum 5-year follow-up (mean, 6.8 years). All patients were fused distally to either T12 or L1. At latest follow-up, 18 were considered successful (group S), 2 required reoperation to accommodate worsening deformity (group R), and 12 were considered marginal outcomes (group M), as defined by >3 cm coronal imbalance (n = 5), >5 mm worsening of lumbar apical vertebra translation compared with preoperative (n = 4), >1 Nash-Moe grade worsening of lumbar apical vertebra rotation (n = 1), >10° thoracolumbar junction kyphosis which was at least 5° worse than preoperative (n = 5), and lumbar Cobb angle >5° worse than preoperative (n = 2). Clinical outcomes were determined by Scoliosis Research Society (SRS)-30 at final follow-up.

Results. Of the multiple factors considered, 2-month postoperative standing lumbar sagittal alignment was most predictive for long-term outcome (P < 0.019 by Kruskal-Wallis ANOVA). Satisfactory outcomes had statistically significantly greater T12-S1 lordosis than those that were marginal (64.8° (group S) vs. 52.0° ° (group M); P = 0.014) or required reoperation (64.8° [group S] vs. 38.0° [group R]; P < 0.001). Traditionally considered variables such as apical vertebra rotation, apical vertebra translation, Cobb angle magnitudes, coronal and sagittal balance, and their respective thoracic-to-lumbar ratios were not independently significant.

Conclusion. Selective thoracic fusions performed for lumbar “C” modifier scoliotic deformities generally have excellent long-term radiographic and SRS-30 outcomes at 5- to 24-year follow-up. Care should be taken to ensure that overcorrection of the thoracic curve is not performed beyond the ability of the lumbar curve to compensate. Furthermore, consideration of selective thoracic fusion should not be ruled out simply because the patient may have a somewhat stiff lumbar curve based on side-bending radiographs.

We examined the 5- to 24-year outcomes of 32 patients with “C” lumbar curves who underwent selective thoracic fusion. Reduced immediate postoperative lumbar lordosis and thoracic overcorrection were associated with worse radiographic outcomes at final follow-up. Clinical outcomes remained excellent, however, regardless of radiographic outcome.

From the Department of Orthopaedic Surgery, Washington University School of Medicine, St. Louis, MO.

Acknowledgment date: November 4, 2009. Revision date: March 30, 2010. Acceptance date: March 31, 2010.

The manuscript submitted does not contain information about medical device(s)/drug(s).

Medtronic funds were received in support of this work. One or more of the author(s) has/have received or will receive benefits for personal or professional use from a commercial party related directly or indirectly to the subject of this manuscript: e.g., honoraria, gifts, consultancies, royalties, stocks, stock options, decision making position.

Address correspondence and reprint requests to Keith H. Bridwell, MD, Department of Orthopaedic Surgery, Washington University School of Medicine, 660 S Euclid Ave, Campus Box 8233, St. Louis, MO 63110; E-mail: bridwellk@wudosis.wustl.edu.

© 2010 Lippincott Williams & Wilkins, Inc.