Medical Student University of Cincinnati College of Medicine Cincinnati, OH, US
Introduction: Understanding normal spinal alignment during position changes is paramount to surgical outcomes, performance, and avoiding functional disability. Current clinical practice utilizes standing flexion/extension radiographs of the impacted segment to support diagnostic and treatment decisions. Sitting lateral radiographs are also gaining adoption, with recent studies demonstrating the clinical utility in lumbar pathologies. Despite numerous studies investigating neutral standing spinal parameters in healthy adults, the normative spinopelvic motion in acts of daily living remains unknown. The purpose of this proof-of-concept study is to evaluate alignment parameters across the cervical, thoracic, and lumbar spine during ADLs in asymptomatic adults and determine if a larger investigation is indicated.
Methods: Ten healthy, asymptomatic adults (50% female, ages 23-70) had whole body, low dose radiation imaging in standing AP, neutral lateral, flexion and extension views. Neutral sitting AP and slumped sitting lateral views were obtained. Parameters of cervical, thoracic, and lumbar spine and pelvis were evaluated and compared after determining no pathologic alignment or length differences existed in the lower extremities. Standing/sitting views were compared to standing lateral flexion/extension.
Results: All patients had a normal PI (45-60°). Three patients had maximal observed pelvic rotation with standing flexion/extension, 6 with standing-to-sitting, and 1 had equal pelvic rotation in both series. Three patients had 9 degrees or less of pelvic rotation between all changes in position. 9 patients had maximum thoracic spine motion in standing flexion/extension, and 1 in standing-to-sitting. 50% of patients had maximal segmental motion at L4-L5, and 50% at L5-S1. 70% had minimal cervical lordosis (2-3°) changes when transitioning from standing to sitting.
Conclusion : Not all asymptomatic subjects followed the same strategy of movement when transitioning from one posture to another. These observed deviations from what are considered normative patterns are not necessarily indicative of any active pathology; but suggest a subject-specific nature of preferred movement patterns that optimize some hereto not studied physiologic criterion. Further investigation through EOS imaging in a prospective, controlled study to determine normative movements and their clinical implications may be beneficial.
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