Body posture and backpack loading: an upright magnetic resonance imaging study of the adult lumbar spine
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Axial loading of the spine while supine, simulating upright posture, decreases intervertebral disc (IVD) height and lumbar length and increases lumbar lordosis. The purpose of this study is to measure the adult lumbar spine’s response to upright posture and a backpack load using upright magnetic resonance imaging (MRI). We hypothesize that higher spinal loads, while upright and with a backpack, will compress lumbar length and IVD height as well as decrease lumbar lordosis.
Six volunteers (45 ± 6 years) underwent 0.6 T MRI scans of the lumbar spine while supine, upright, and upright with a 10 % body weight (BW) backpack. Main outcomes were IVD height, lumbar spinal length (distance between anterior–superior corners of L1 and S1), and lumbar lordosis (Cobb angle between the superior endplates of L1 and S1).
The 10 % BW load significantly compressed the L4–L5 and L5–S1 IVDs relative to supine (p < 0.05). The upright and upright plus 10 % BW backpack conditions significantly compressed the anterior height of L5–S1 relative to supine (p < 0.05), but did not significantly change the lumbar length or lumbar lordosis.
The L4–L5 and L5–S1 IVDs compress, particularly anteriorly, when transitioning from supine to upright position with a 10 % BW backpack. This study is the first radiographic analysis to describe the adult lumbar spine wearing common backpack loads. The novel upright MRI protocol described allows for functional, in vivo, loaded measurements of the spine that enables the study of spinal biomechanics and therapeutic interventions.
KeywordsDisc compression Backpack MRI Upright MRI Intervertebral disc
The authors would like to gratefully acknowledge the participation of our six subjects. We thank JR Bachman for technical support and help with revisions. We thank Dr. Brandon Macias for help with manuscript editing, Dr. Stephen Chiang for his assistance with MR imaging and analysis, Clifford Mao for his help with the repeatability measurements, Dr. Lin Liu for her help with the statistical analysis, and Dr. Steven Garfin for support. This study was supported by the National Aeronautics and Space Administration Grant NNX10AM18G and the UCSD Clinical Translational Research Institute fellowship award.
Conflict of interest
- 6.Lee SH, Hargens AR, Fredericson M, Lang P (2003) Lumbar spine disc heights and curvature: upright posture vs. supine compression harness. Aviat Sp Env Med 74:512–516Google Scholar
- 12.Shymon S, Hargens AR, Minkoff LA, Chang DG (2013) Body position and backpack loading: an upright magnetic resonance imaging study of the adult lumbar spine. Poster session presented at: Federation of American Societies for Experimental Biology Conference, BostonGoogle Scholar
- 18.Schmid MR, Dueweii S, Romanowski B, Hodler J (1999) Changes in cross-sectional measurements of the spinal canal and intervertebral foramina as a function of body position: in vivo studies on an open-configuration MR system. Am J Roentgenol 1095–1102Google Scholar
- 20.Wisneski RJ, Garfin SR, Rothman RH (1999) Lumbar disc disease. In: Herkowitz HN, Garfin SR, Balderston RA (eds) Spine, vol 1. WB Saunders, Philadelphia, pp 613–679Google Scholar
- 21.White AA, Panjabi MM (1990) Clinical biomechanics of the spine, 2nd edn. JB Lippincott, PhiladelphiaGoogle Scholar
- 27.Sayson JV, Hargens AR (2008) Pathophysiology of low back pain during exposure to microgravity. Aviat Sp Env Med 79:364–373Google Scholar
- 28.Styf JR, Ballard RE, Fechner K, Watenpaugh DE, Kahan NJ, Hargens AR (1997) Height increase, neuromuscular function, and back pain during 6 degrees head-down tilt with traction. Aviat Sp Env Med 68:24–29Google Scholar