TheT1 pelvic angle, a novel radiographic measure of global sagittal deformity, accounts for both spinal inclination and pelvic tilt and correlates with health-related quality of life.

dc.contributor.author

Protopsaltis, Themistocles

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Schwab, Frank

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Bronsard, Nicolas

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Smith, Justin S

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Klineberg, Eric

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Mundis, Gregory

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Ryan, Devon J

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Hostin, Richard

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Hart, Robert

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Burton, Douglas

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Ames, Christopher

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Shaffrey, Christopher

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Bess, Shay

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Errico, Thomas

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Lafage, Virginie

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International Spine Study Group

dc.date.accessioned

2023-07-20T20:04:17Z

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2023-07-20T20:04:17Z

dc.date.issued

2014-10

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2023-07-20T20:03:47Z

dc.description.abstract

Background

Adult spinal deformity is a prevalent cause of pain and disability. Established measures of sagittal spinopelvic alignment such as sagittal vertical axis and pelvic tilt can be modified by postural compensation, including pelvic retroversion, knee flexion, and the use of assistive devices for standing. We introduce the T1 pelvic angle, a novel measure of sagittal alignment that simultaneously accounts for both spinal inclination and pelvic retroversion. The purpose of this study was to investigate the relationship of the T1 pelvic angle and other established sagittal alignment measures and to correlate these parameters with health-related quality-of-life measures.

Methods

This is a multicenter, prospective, cross-sectional analysis of consecutive patients with adult spinal deformity. Inclusion criteria were adult spinal deformity, an age of greater than eighteen years, and any of the following: scoliosis, a Cobb angle of ≥ 20°, sagittal vertical axis of ≥ 5 cm, thoracic kyphosis of ≥ 60°, and pelvic tilt of ≥ 25°. Clinical measures of disability included the Oswestry Disability Index (ODI), Scoliosis Research Society (SRS)-22, and Short Form-36 (SF-36) questionnaires.

Results

Five hundred and fifty-nine consecutive patients with adult spinal deformity (mean age, 52.5 years) were enrolled. The T1 pelvic angle correlated with the sagittal vertical axis (r = 0.837), pelvic incidence minus lumbar lordosis (r = 0.889), and pelvic tilt (0.933). Categorizing the patients by increasing T1 pelvic angle (<10°, 10° to 20°, 21° to 30°, and > 30°) revealed a significant and progressive worsening in health-related quality of life (p < 0.001 for all). The T1 pelvic angle and sagittal vertical axis correlated with the ODI (0.435 and 0.455), SF-36 Physical Component Summary (-0.445 and -0.458), and SRS (-0.358 and -0.383) (p < 0.001 for all). Utilizing a linear regression analysis, a T1 pelvic angle of 20° corresponded to a severe disability (an ODI of >40), and the meaningful change in T1 pelvic angle corresponding to one minimal clinically important difference was 4.1° on the ODI.

Conclusions

The T1 pelvic angle correlates with health-related quality of life in patients with adult spinal deformity. The T1 pelvic angle is related to both pelvic tilt and sagittal vertical axis; however, unlike sagittal vertical axis, it does not vary on the basis of the extent of pelvic retroversion or patient support in standing. Since the T1 pelvic angle is an angular and not a linear measure, it does not require calibration of the radiograph. Thus, the T1 pelvic angle measures sagittal deformity independent of many postural compensatory mechanisms, and it can be useful as a preoperative planning tool, with a target T1 pelvic angle of < 14°.

Level of evidence

Diagnostic Level II. See Instructions for Authors for a complete description of levels of evidence.
dc.identifier

96/19/1631

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0021-9355

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1535-1386

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https://hdl.handle.net/10161/28527

dc.language

eng

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Ovid Technologies (Wolters Kluwer Health)

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The Journal of bone and joint surgery. American volume

dc.relation.isversionof

10.2106/jbjs.m.01459

dc.subject

International Spine Study Group

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Pelvic Bones

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Thoracic Vertebrae

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Humans

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Spinal Curvatures

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Radiography

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Regression Analysis

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Prospective Studies

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Cross-Sectional Studies

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Quality of Life

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Adolescent

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Adult

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Aged

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Aged, 80 and over

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Middle Aged

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Female

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Male

dc.title

TheT1 pelvic angle, a novel radiographic measure of global sagittal deformity, accounts for both spinal inclination and pelvic tilt and correlates with health-related quality of life.

dc.type

Journal article

duke.contributor.orcid

Shaffrey, Christopher|0000-0001-9760-8386

pubs.begin-page

1631

pubs.end-page

1640

pubs.issue

19

pubs.organisational-group

Duke

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School of Medicine

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Clinical Science Departments

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Orthopaedic Surgery

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Neurosurgery

pubs.publication-status

Published

pubs.volume

96

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