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Lumbopelvic Rhythm during Forward and Backward Sagittal Trunk Rotations; in vivo Measurements Using Inertial Sensors

Tafazzol, Alireza | 2014

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 45255 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Arjmand, Navid
  7. Abstract:
  8. Direct in vivo measurements of spinal loads and muscle forces are invasive. Investigators have thus used musculoskeletal biomechanical models that require kinematic data including trunk and pelvis angular movements as their inputs. . Novel devices measure anglular movements using both inertial sensors (such as gyroscopes and accelerometers) and miniature magnetometers. Relative low cost, portability, and accuracy are among specific characteristics of inertial tracking devices. The main objective of the present study was set to measure spinal kinematics including the lumbopelvic rhythm as the ratio of total lumbar rotation over pelvic rotation during trunk sagittal movement which is essential to evaluate spinal loads and discriminate between low back pain and asymptomatic population. Angular rotations of the pelvis and lumbar spine as well as their sagittal rhythmduring forward flexion and backward extension in upright standing of eight asymptomatic males are measured using an inertial tracking device. The mean of peak voluntary flexion rotations of the thorax, pelvis, and lumbar was 121° (SD 9.9), 53.0° (SD 5.2), and 60.2° (SD 8.6), respectively. The mean lumbopelvic ratios decreased from 2.51 in 0–30° of trunk flexion to 1.34 in 90–120° range during forward bending while it increased from 1.23 in 90–120° range to 2.86 in 0–30° range during backward extension. A simultaneous rhythm between the lumbar and pelvis movements was found during both forward and backward trunk movements. While the lumbar spine contributed more to the trunk rotation during early and final stages of forward flexion and backward extension, respectively, the pelvis contributedmore during final and early stages of forward flexion and backward extension, respectively. Finally, the effect of variations in the lumbopelvic ratio during trunk flexion on spinal loads is quantified using a detailed musculoskeletal model. Variations in the lumbopelvic ratio from 0.5 to 3 (with an interval of 0.25) at any trunk flexion angle generally reduced the L5–S1 compression and shear forces by up to 21 and 45%, respectively. The measured lumbopelvic ratios resulted overall in near-optimal (minimal) L5–S1 compression forces. Hence, our healthy subjects adapted a lumbopelvic coordination that diminished L5–S1 compression force
  9. Keywords:
  10. Spine ; Kinematics ; Inertial Sensor ; Ambulatory Measurement ; Lumbopelvic Rhythm

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