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Pelvic Tilt and Truncal Inclination: Two Key Radiographic Parameters in the Setting of Adults With Spinal Deformity

Lafage, Virginie, PhD; Schwab, Frank, MD; Patel, Ashish, MD; Hawkinson, Nicola, NP; Farcy, Jean-Pierre, MD

doi: 10.1097/BRS.0b013e3181aad219
Deformity
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Study Design. Prospective radiographic and clinical analysis.

Objective. Investigate the relationship between spino-pelvic parameters and patient self reported outcomes on adult subjects with spinal deformities.

Summary of Background Data. It is becoming increasingly recognized that the study of spinal alignment should include pelvic position. While pelvic incidence determines lumbar lordosis, pelvic tilt (PT) is a positional parameter reflecting compensation to spinal deformity. Correlation between plumbline offset (sagittal vertical axis [SVA]) and Health Related Quality of Life (HRQOL) measures has been demonstrated, but such a study is lacking for PT.

Methods. This prospective study was carried out on 125 adult patients suffering from spinal deformity (mean age: 57 years). Full-length free-standing radiographs including the spine and pelvis were available for all patients. HRQOL instruments included: Oswestry Disability Index, Short Form-12, Scoliosis Research Society. Correlation analysis between radiographic spinopelvic parameters and HRQOL measures was pursued.

Results. Correlation analysis revealed no significance pertaining to coronal plane parameters. Significant sagittal plane correlations were identified. SVA and truncal inclination measured by T1 spinopelvic inclination (T1–SPI) (angle between T1–hip axis and vertical) correlated with: Scoliosis Research Society (appearance, activity, total score), Oswestry Disability Index, and Short Form-12 (physical component score). Correlation coefficients ranged from 0.42 < r < 0.55 (P < 0.0001). T1–SPI revealed greater correlation with HRQOL compared to SVA. PT showed correlation with HRQOL (0.28 < r < 0.42) and with SVA (r = 0.64, P < 0.0001).

Conclusion. This study confirms that pelvic position measured via PT correlates with HRQOL in the setting of adult deformity. High values of PT express compensatory pelvic retroversion for sagittal spinal malalignment. This study also demonstrates significant T1–SPI correlation with HRQOL measures and outperforms SVA. This parameter carries the advantage of being an angular measurement which avoids the error inherent in measuring offsets in noncalibrated radiographs.

Sagittal alignment of patients with spinal deformities is a complex disorder. By analyzing correlations between Health Related Quality of Life instruments and radiographic parameters, this study demonstrates that spinopelvic inclination (trunk inclination) and pelvic tilt (pelvic retroversion) are 2 key parameters tied to self reported pain and function within this population.

From the NYU Hospital for Joint Diseases, New York, NY.

Acknowledgment date: May 21, 2008. Revision date: January 18, 2009. Acceptance date: February 23, 2009.

The manuscript submitted does not contain information about medical device(s)/drug(s).

Corporate/Industry 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.

Supported by Medtronic Sofamor Danek.

Address correspondence and reprint requests to Virginie Lafage, PhD, NYU Hospital for Joint Diseases, 380 2nd Ave, Suite 1001, New York, NY 10010; E-mail: virginie.lafage@gmail.com

© 2009 Lippincott Williams & Wilkins, Inc.