NARRATIVE REVIEWSAdjacent Segment Disease in the Cervical and Lumbar SpineTobert, Daniel G. MD*; Antoci, Valentin MD, PhD†; Patel, Shaun P. MD*; Saadat, Ehsan MD*; Bono, Christopher M. MD‡Author Information *Harvard Combined Orthopaedic Residency Program, Boston, MA †Department of Orthopaedic Surgery, University Orthopaedics, Providence, RI ‡Department of Orthopaedic Surgery, Brigham and Women’s Hospital, Boston, MA Human research subjects were not used in the manuscript and therefore this is exempt from IRB review. The authors declare no conflict of interest. Reprints: Daniel G. Tobert, MD, Department of Orthopaedic Surgery, Harvard Combined Orthopaedic Residency Program, 55 Fruit St, WHT 5, Boston, MA 02114 (e-mail: [email protected]). Clinical Spine Surgery: April 2017 - Volume 30 - Issue 3 - p 94-101 doi: 10.1097/BSD.0000000000000442 Buy Metrics Abstract Adjacent segment disease (ASD) is disappointing long-term outcome for both the patient and clinician. In contrast to adjacent segment degeneration, which is a common radiographic finding, ASD is less common. The incidence of ASD in both the cervical and lumbar spine is between 2% and 4% per year, and ASD is a significant contributor to reoperation rates after spinal arthrodesis. The etiology of ASD is multifactorial, stemming from existing spondylosis at adjacent levels, predisposed risk to degenerative changes, and altered biomechanical forces near a previous fusion site. Numerous studies have sought to identify both patient and surgical risk factors for ASD, but a consistent, sole predictor has yet to be found. Spinal arthroplasty techniques seek to preserve physiological biomechanics, thereby minimizing the risk of ASD, and long-term clinical outcome studies will help quantify its efficacy. Treatment strategies for ASD are initially nonoperative, provided a progressive neurological deficit is not present. The spine surgeon is afforded many surgical strategies once operative treatment is elected. The goal of this manuscript is to consider the etiologies of ASD, review its manifestations, and offer an approach to treatment. Copyright © 2016 Wolters Kluwer Health, Inc. All rights reserved.