Proximal Junctional Kyphosis in Adult Spinal Deformity: Definition, Classification, Risk Factors, and Prevention Strategies

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Abstract

Proximal junctional problems are among the potential complications of surgery for adult spinal deformity (ASD) and are associated with higher morbidity and increased rates of revision surgery. The diverse manifestations of proximal junctional problems range from proximal junctional kyphosis (PJK) to proximal junctional failure (PJF). Although there is no universally accepted definition for PJK, the most common is a proximal junctional angle greater than 10° that is at least 10° greater than the preoperative measurement. PJF represents a progression from PJK and is characterized by pain, gait disturbances, and neurological deficits. The risk factors for PJK can be classified according to patient-related, radiological, and surgical factors. Based on an understanding of the modifiable factors that contribute to reducing the risk of PJK, prevention strategies are critical for patients with ASD.

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Most cited references 59

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Scoliosis Research Society-Schwab adult spinal deformity classification: a validation study.

Frank Schwab, Benjamin Ungar, Benjamin Blondel … (2012)

Inter- and intra-rater variability study. On the basis of a Scoliosis Research Society effort, this study seeks to determine whether the new adult spinal deformity (ASD) classification system is clear and reliable. A classification of adult ASD can serve several purposes, including consistent characterization of a clinical entity, a basis for comparing different treatments, and recommended treatments. Although pediatric scoliosis classifications are well established, an ASD classification is still being developed. A previous classification developed by Schwab et al has met with clinical relevance but did not include pelvic parameters, which have shown substantial correlation with health-related quality of life measures in recent studies. Initiated by the Scoliosis Research Society Adult Deformity Committee, this study revised a previously published classification to include pelvic parameters. Modifier cutoffs were determined using health-related quality of life analysis from a multicenter database of adult deformity patients. Nine readers graded 21 premarked cases twice each, approximately 1 week apart. Inter- and intra-rater variability and agreement were determined for curve type and each modifier separately. Fleiss' kappa was used for reliability measures, with values of 0.00 to 0.20 considered slight, 0.21 to 0.40 fair, 0.41 to 0.60 moderate, 0.61 to 0.80 substantial, and 0.81 to 1.00 almost perfect agreement. Inter-rater kappa for curve type was 0.80 and 0.87 for the 2 readings, respectively, with modifier kappas of 0.75 and 0.86, 0.97 and 0.98, and 0.96 and 0.96 for pelvic incidence minus lumbar lordosis (PI-LL), pelvic tilt (PT), and sagittal vertical axis (SVA), respectively. By the second reading, curve type was identified by all readers consistently in 66.7%, PI-LL in 71.4%, PT in 95.2%, and SVA in 90.5% of cases. Intra-rater kappa averaged 0.94 for curve type, 0.88 for PI-LL, 0.97 for PT, and 0.97 for SVA across all readers. Data from this study show that there is excellent inter- and intra-rater reliability and inter-rater agreement for curve type and each modifier. The high degree of reliability demonstrates that applying the classification system is easy and consistent.

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The impact of positive sagittal balance in adult spinal deformity.

Steven Glassman, Keith H Bridwell, John R Dimar … (2005)

This study is a retrospective review of 752 patients with adult spinal deformity enrolled in a multicenter prospective database in 2002 and 2003. Patients with positive sagittal balance (N = 352) were further evaluated regarding radiographic parameters and health status measures, including the Scoliosis Research Society patient questionnaire, MOS short form-12, and Oswestry Disability Index. To examine patients with adult deformity with positive sagittal balance to define parameters within that group that might differentially predict clinical impact. In a multicenter study of 298 adults with spinal deformity, positive sagittal balance was identified as the radiographic parameter most highly correlated with adverse health status outcomes. Radiographic evaluation was performed according to a standardized protocol for 36-inch standing radiographs. Magnitude of positive sagittal balance and regional sagittal Cobb angle measures were recorded. Statistical correlation between radiographic parameters and health status measures were performed. Potentially confounding variables were assessed. Positive sagittal balance was identified in 352 patients. The C7 plumb line deviation ranged from 1 to 271 mm. All measures of health status showed significantly poorer scores as C7 plumb line deviation increased. Patients with relative kyphosis in the lumbar region had significantly more disability than patients with normal or lordotic lumbar sagittal Cobb measures. This study shows that although even mildly positive sagittal balance is somewhat detrimental, severity of symptoms increases in a linear fashion with progressive sagittal imbalance. The results also show that kyphosis is more favorable in the upper thoracic region but very poorly tolerated in the lumbar spine.

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Classification of the normal variation in the sagittal alignment of the human lumbar spine and pelvis in the standing position.

J. Dimnet, Pierre Roussouly, Sohrab Gollogly … (2005)

A prospective radiographic study of 160 volunteers without symptoms of spinal disease was conducted. The objective of this study was to describe, quantify, and classify common variations in the sagittal alignment of the spine, sacrum, and pelvis. Previous publications have documented the high degree of variability in the sagittal alignment of the spine. Other studies have suggested that specific changes in alignment and the characteristics of the lumbar lordosis are responsible for degenerative changes and symptomatic back pain. In the course of this study, anteroposterior and lateral radiographs of 160 volunteers in a standardized standing position were taken. A custom computer application was used to analyze the alignment of the spine and pelvis on the lateral radiographs. A four-part classification scheme of sagittal morphology was used to classify each patient. Reciprocal relationships between the orientation of the sacrum, the sacral slope, the pelvic incidence, and the characteristics of the lumbar lordosis were evident. The global lordotic curvature, lordosis tilt angle, position of the apex, and number or lordotic vertebrae were determined by the angle of the superior endplate of S1 with respect to the horizontal axis. Understanding the patterns of variation in sagittal alignment may help to discover the association between spinal balance and the development of degenerative changes in the spine.

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Author and article information

Journal

Journal ID (nlm-ta): Asian Spine J

Journal ID (iso-abbrev): Asian Spine J

Title: Asian Spine Journal

Publisher: Korean Society of Spine Surgery

ISSN (Print): 1976-1902

ISSN (Electronic): 1976-7846

Publication date (Print): June 2022

Publication date (Electronic): 30 April 2021

Volume: 16

Issue: 3

Pages: 440-450

Affiliations

[1 ]Department of Orthopaedic Surgery, Inje University Sanggye Paik Hospital, Inje University College of Medicine, Seoul, Korea

[2 ]Department of Orthopaedic Surgery, Korea University Guro Hospital, Korea University College of Medicine, Seoul, Korea

[3 ]Department of Orthopaedic Surgery, College of Medicine, The Catholic University of Korea, Seoul, Korea

[4 ]Department of Orthopaedic Surgery, Chung-Ang University Hospital, Chung-Ang University College of Medicine, Seoul, Korea

[5 ]Department of Orthopaedic Surgery, Montefiore Medical Center, Albert Einstein College of Medicine, Bronx, NY, USA

Author notes

Corresponding author: Dong-Gune Chang, Department of Orthopaedic Surgery, Inje University Sanggye Paik Hospital, Inje University College of Medicine, 1342 Dongil-ro, Nowon-gu, Seoul 01757, Korea, Tel: +82-2-950-1284, Fax: +82-2-950-1287, E-mail: dgchangmd@ 123456gmail.com

[*]

These two authors contributed equally to this work as a co-first author.

Article

Publisher ID: asj-2020-0574

DOI: 10.31616/asj.2020.0574

PMC ID: 9260397

PubMed ID: 33910320

SO-VID: 1027257f-d76e-48dd-a32d-b0a796603236

License:

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License ( http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

History

Date received : 10 November 2020

Date revision received : 09 February 2021

Date accepted : 15 February 2021

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