The effect of pelvic motion on spino-pelvic parameters

Publication date: Available online 15 August 2017
Source:The Spine Journal
Author(s): Andrew M. Hayden, Ann M. Hayes, Jennifer L. Brechbuhler, Heidi Israel, Howard M. Place
Background ContextTo date, many studies have examined how pelvic position affects the spinal curvature and spino-pelvic parameters. However, these studies focus on a static relationship, comparing pelvis and spine in a relaxed or baseline position only. Indeed, the spino-pelvic connection is dynamic, as a subject can easily be taught to rotate their pelvis anteriorly or posteriorly on the femoral head, all while maintaining an erect posture. Therefore, for a true understanding of pelvic influence on the spinal column, it is necessary to examine spino-pelvic parameters in multiple pelvic positions within the same subject.PurposeThe objective of this study was to examine the dynamic effect of pelvic motion on the spine and associated radiographic parameters.Study DesignSingle-center, cross-sectional study of 50 healthy, asymptomatic volunteers.Patient SampleSubjects were recruited and screened based upon the following criteria: *Between 18-79 years of age. *No known spinal, pelvic, or lower extremity pain lasting greater than 48 hours. *No history of spinal, pelvic, or lower extremity dysfunction requiring medical care. *No radiographic evidence of spinal or pelvic abnormality, scoliosis deformity, or other associated spinal pathologies. *Not currently pregnant and with no possibility of being pregnant. *BMI < 30 64 subjects were screened and 14 were excluded for a total of 50 subjects.Outcome MeasuresThoracic Kyphosis (TK), Lumbar Lordosis (LL), Sagittal Vertical Axis (SVA), Pelvic Tilt (PT) Sacral Slope (SS), and Pelvic Incidence (PI)MethodsThis study was funded by a Small Exploratory Research Grant from the Scoliosis Research Society. Each subject was instructed and observed to stand in 3 different positions: pelvic resting, anterior pelvic rotation and posterior pelvic rotation. Lateral standing radiographs were taken in each position and each image was examined by an Orthopaedic spine surgeon who digitally measured: thoracic kyphosis, lumbar lordosis, sagittal vertical axis, pelvic tilt, sacral slope, and pelvic incidence. The data was then statistically examined to determine the affect of pelvic position on each parameter. None of the authors have any relevant financial relationships or commercial interests to disclose.ResultsSubjects demonstrated a measurable, statistically significant change in each parameter with pelvic rotation. There was a clear pattern of change for LL, PT, and SS with anterior and posterior pelvic rotation. A change in LL demonstrated a strong correlation with changes in all measured parameters with pelvic rotation.ConclusionsIn asymptomatic subjects, pelvic motion affects the position of the spinal column and resultant spino-pelvic parameters. The results of this study demonstrate that one can intentionally change the position of the pelvis and adjacent spinal column in space. Knowledge of this relationship is important to the understanding of sagittal balance and could influence treatment of patients with spinal deformity.



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