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Progressive Junctional Kyphosis at the Caudal End of Lumbar Instrumented Fusion: Etiology, Predictors, and Treatment

Kwon, Brian K. MD, PhD, FRCSC*; Elgafy, Hossein MD, FRCSC*; Keynan, Ory MD†; Fisher, Charles G. MD, MPH, FRCSC*; Boyd, Michael C. MD, MSc, FRCSC‡; Paquette, Scott J. MD, FRCSC‡; Dvorak, Marcel F. MD, FRCSC*

doi: 10.1097/01.brs.0000229258.83071.db
Deformity

Study Design. Clinical case series.

Objective. To describe a series of patients with progressive sagittal decompensation caused by failure at the caudal end of an instrumented lumbar fusion.

Summary of Background Data. Lumbar kyphosis in association with global sagittal decompensation can be a disabling problem, particularly as a late complication of distraction instrumentation. Although kyphosis at the rostral end of instrumented fusions secondary to adjacent segment degeneration has been well described, substantially less has been documented about failure and kyphosis at the caudal end.

Methods. Patients who have a progressive lumbar kyphosis and sagittal decompensation requiring operative revision were retrospectively reviewed, and radiographic measurements of lumbar lordosis and sagittal balance were performed to study this problem.

Results. There were 13 patients identified. The most common mode of caudal junctional decompensation was related to failure of the most distal fixation. Sagittal decompensation occurred even in the presence of satisfactory lumbar lordosis. Revision surgery and improved sagittal balance were achieved typically using the technique of pedicle subtraction osteotomy and extension of the instrumentation to the sacrum. Osteoporosis, hip osteoarthritis, and substance abuse were commonly observed associations.

Conclusions. Fixation failure at the caudal end of lumbar-instrumented fusion should be considered in patients with progressive sagittal decompensation. The high potential for failure of L5 pedicle screws after the index surgery warrants serious consideration of extending such fusions into the sacrum/ilium.

This study reviews 13 patients who had progressive kyphotic decompensation caused by failure at the caudal end of an instrumented lumbar fusion. Most patients had failure of the L5 pedicle screws, and global sagittal imbalance often occurred despite the achievement of satisfactory lumbar lordosis. Revision was achieved with pedicle subtraction osteotomy.

From the *Division of Spine, Department of Orthopaedics, University of British Columbia and the Combined Neurosurgical and Orthopaedic Spine Program at the Vancouver Coastal Health Research Institute at the Vancouver General Hospital, Vancouver, Canada; †Department of Orthopaedic Surgery “B,” Tel-Aviv Sourasky Medical Center, Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel; and ‡Division of Neurosurgery, Department of Surgery, University of British Columbia and the Combined Neurosurgical and Orthopaedic Spine Program at the Vancouver Coastal Health Research Institute at the Vancouver General Hospital, Vancouver, Canada.

Acknowledgment date: September 12, 2005. First revision date: October 31, 2005. Acceptance date: November 1, 2005.

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

No funds were received in support of this work. No benefits in any form have been or will be received from a commercial party related directly or indirectly to the subject of this manuscript.

Address correspondence and reprint requests to Marcel F. Dvorak, MD, FRCSC, D-609 Heather Pavilion, 2733 Heather Street, Vancouver, BC, Canada, V5Z 3J5; E-mail: Marcel.Dvorak@vch.ca

© 2006 Lippincott Williams & Wilkins, Inc.