Pelvic tilt and truncal inclination: two key radiographic parameters in the setting of adults with spinal deformity.
METHODS
Prospective radiographic and clinical analysis.


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


BACKGROUND
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).


CONCLUSIONS
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.
Lafage
Virginie
V
NYU Hospital for Joint Diseases, New York, NY 10010, USA. virginie.lafage@gmail.com
Schwab
Frank
F
Patel
Ashish
A
Hawkinson
Nicola
N
Farcy
Jean-Pierre
JP
D000203:Activities of Daily Living; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000886:Anthropometry / Q000379:methods*; D015331:Cohort Studies; D004185:Disability Evaluation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010388:Pelvis / Q000000981:diagnostic imaging* / Q000473:pathology / Q000503:physiopathology; D011187:Posture / Q000502:physiology*; D011788:Quality of Life; D011859:Radiography; D012647:Self-Assessment; D012720:Severity of Illness Index; D013121:Spinal Curvatures / Q000000981:diagnostic imaging* / Q000473:pathology / Q000503:physiopathology; D011795:Surveys and Questionnaires; D055815:Young Adult