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Factors Affecting the Postoperative Progression of Thoracic Kyphosis in Surgically Treated Adult Patients With Lumbar Degenerative Scoliosis

Yagi, Mitsuru MD, PhD*; Hosogane, Naobumi MD, PhD; Okada, Eijiro MD, PhD; Watanabe, Kota MD, PhD§; Machida, Masafumi MD, PhD*; Tezuka, Masaki MD, PhD; Matsumoto, Morio MD, PhD; Asazuma, Takashi MD, PhD*; Keio Spine Research Group

doi: 10.1097/BRS.0000000000000226
Deformity

Study Design. A retrospective case series of patients treated surgically for degenerative lumbar scoliosis (DLS).

Objective. To determine incidence and risk factors of progressive global thoracic kyphosis (pGTK) after surgery for DLS.

Summary of Background Data. Sagittal balance affects the surgical treatment of spinal deformity in adults. Little is known about the loss of sagittal balance due to pGTK, or about the risk factors for pGTK, after surgery for DLS.

Methods. We reviewed records from a multicenter database of adults with DLS, treated with posterior spinal fusion. Inclusion required an age of 50 years or more at the time of surgery, an upper instrumented vertebra at T9 and below, more than 5 fused segments, and at least 2 years of follow-up. We included 73 patients with a mean age of 68.3 years (range, 51–77 yr) and a mean follow-up period of 3.6 years (range, 2–11 yr). Independent risk factors for pGTK were identified by logistic regression analysis.

Results. Significant pGTK, defined as an increase in thoracic kyphosis of more than 10° from before surgery to the time of final follow-up, was observed in 41% of the patients. Loss of the sagittal vertical axis was larger in patients with pGTK than without (4.7 vs. 1.5 cm; P = 0.02). Risk analysis showed larger lumbar lordosis correction in patients with pGTK. Multivariate logistic regression analysis identified an age greater than 75 (odds ratio, 5.53; P = 0.02, 95% confidence interval [1.4–22.4]) and sacropelvic fusion (odds ratio = 2.66, P = 0.02, 95% confidence interval [1.5–11.1]) as independent risk factors for pGTK.

Conclusion. The pGTK incidence after surgery for DLS was 41%. Age, sacropelvic fusion, and a larger sagittal correction were identified as pGTK risk factors. Long-term follow-up will provide more data on the clinical impact of pGTK in elderly patients.

Level of Evidence: 3

The incidence of postoperative progression of thoracic kyphosis greater than 10° was 41% in surgically treated patients with degenerative lumbar scoliosis. Our data indicated age, sacropelvic fusion, and a large amount correction of lumbar lordosis as risk factors for postoperative progression of thoracic kyphosis.

*Department of Orthopedic Surgery, National Center for Musculoskeletal Disorders, Murayama Medical Center, Tokyo, Japan

Department of Orthopedics, Keio University School of Medicine, Tokyo, Japan

Department of Orthopedics, Saiseikai Central Hospital, Tokyo, Japan

§Department of Advanced Therapy for Spine and Spinal Cord Disorders, Keio University School of Medicine, Tokyo, Japan; and

KSRG, Tokyo, Japan.

Address correspondence and reprint requests to Mitsuru Yagi, MD, PhD, Department of Orthopedic Surgery, National Center for Musculoskeletal Disorders, Murayama Medical Center, 2-37-1 Gakuen, Musashi-Murayama City Tokyo, Japan; E-mail: yagiman@gmail.com

Acknowledgment date: September 13, 2013. First revision date: January 3, 2014. Acceptance date: January 9, 2014.

The legal regulatory status of the device(s)/drug(s) that is/are the subject of this manuscript is not applicable in my country.

No funds were received in support of this work.

Relevant financial activities outside the submitted work: grants/grants pending and payment for lectures.

© 2014 by Lippincott Williams & Wilkins