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Selective Thoracic Fusion in Lenke 1C Curves: Prevalence and Criteria

Crawford, Charles H. III MD*; Lenke, Lawrence G. MD; Sucato, Daniel J. MD, MS; Richards, B. Stephens III MD; Emans, John B. MD§; Vitale, Michael G. MD; Erickson, Mark A. MD; Sanders, James O. MD**

doi: 10.1097/BRS.0b013e3182987360
Deformity

Study Design. Multicenter retrospective analysis of prospectively collected data.

Objective. Evaluate radiographical and clinical characteristics of patients undergoing a selective thoracic fusion (STF) for Lenke 1C curves.

Summary of Background Data. STF of adolescent idiopathic scoliosis has been advocated for the so-called “false double major” curve (Lenke 1C/King type II). Despite these recommendations, many surgeons continue to perform nonselective fusions for this curve type. It is unknown to what extent other factors influence the surgeon's fusion-level selection.

Methods. A prospective multicenter database included 264 patients with surgically treated Lenke 1C curves and were divided into 2 groups. The STF group included patients with the lowest instrumented vertebra at or cephalad to L1, whereas the nonselective fusion group included patients with the lowest instrumented vertebra at or caudal to L3. Preoperative radiographical, clinical (scoliometer), Scoliosis Appearance Questionnaire (SAQ), and Scoliosis Research Society (SRS) questionnaires were analyzed and compared.

Results. Only 138 of 264 patients (49%) underwent an STF. Sex ratio (90% vs. 86% female), average age (14.7 vs. 14.8 yr), and preoperative main thoracic Cobb angles (56.0° ± 9.9°vs. 55.3° ± 11.4°) were not significantly different (STF vs. nonselective fusion). However, the average thoracolumbar/lumbar (TL/L) preoperative Cobb angle was significantly smaller in the STF group (42.1° ± 8.6° vs. 47.0° ± 9.0°; P < 0.001), whereas the main thoracic: TL/L Cobb ratio (1.35 ± 0.20 vs. 1.18 ± 0.15; P < 0.001), apical vertebral translation, and rotation (1.82 ± 0.59 vs. 1.31 ± 0.53; P < 0.001), (1.16 vs. 0.98; P < 0.001) ratios were significantly greater in the STF group. Preoperative coronal balance, sagittal Cobb angles (including T10–L2 kyphosis) and Risser Grade were not significantly different. Preoperative TL/L scoliometer measures were significantly less in the STF group (8.1° ± 3.7° vs. 10.3° ± 5.4°; P = 0.001). On the SAQ, the STF group had less desire for an appearance change.

Conclusion. Despite the recommendation to fuse only the structural thoracic curve in a 1C curve, only 49% of patients were treated with an STF. Those undergoing an STF had smaller TL/L Cobb angles, less TL/L clinical deformity, larger main thoracic: TL/L ratios, and less desire for an appearance change.

Level of Evidence: 3

Factors not included in the Lenke classification system are being used to select fusion levels (selective thoracic vs. fusion of both curves) for type 1C curves. Patients who underwent a selective thoracic fusion had a smaller thoracolumbar/lumbar (TL/L) Cobb angle, larger main thoracic: TL/L ratios, and less desire to change their appearance.

*Norton Leatherman Spine Center, Louisville, KY

Washington University School of Medicine, St. Louis, MO

Texas Scottish Rite Hospital, Dallas, TX

§Harvard Medical School, Children's Hospital, Boston, MA

Columbia Presbyterian Medical Center, New York, NY

The Children's Hospital, Aurora, CO; and

**University of Rochester Medical Center, Rochester, NY.

Address correspondence and reprint requests to Lawrence G. Lenke, MD, Washington University School of Medicine, Department of Orthopaedic Surgery, 660 S. Euclid Ave, Campus Box 8233, Saint Louis, MO 63110; E-mail: lenkel@wudosis.wustl.edu

Acknowledgment date: January 29, 2013. First revision date: April 3, 2013. Acceptance date: April 20, 2013.

The device(s)/drug(s) is/are FDA-approved or approved by corresponding national agency for this indication.

Medtronic funds were received to support this work.

Relevant financial activities outside the submitted work: board membership, consultancy, honorarium, grants pending, travel/accommodations/meeting expenses, royalties, patents, and stock/stock options.

© 2013 by Lippincott Williams & Wilkins