Chinese Journal of Tissue Engineering Research ›› 2016, Vol. 20 ›› Issue (9): 1282-1288.doi: 10.3969/j.issn.2095-4344.2016.09.010

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Effect of weight-bearing activity on the center of rotation in the lower lumbar vertebrae

Liu Jia-nan1, 2, Xia Qun2, Miao Jun2, Li Hong-da1, 2, Wei Dong2, 3   

  1. 1Graduate School of Tianjin Medical University, Tianjin 300070, China; 2Tianjin Hospital, Tianjin 300211, China; 3Graduate School of Tianjin University of Traditional Chinese Medicine, Tianjin 300193, China
  • Received:2016-01-19 Online:2016-02-19 Published:2016-02-19
  • Contact: Xia Qun, Chief physician, Tianjin Hospital, Tianjin 300211, China
  • About author:Liu Jia-nan, Studying for master’s degree, Graduate School of Tianjin Medical University, Tianjin 300070, China; Tianjin Hospital, Tianjin 300211, China
  • Supported by:
    the National Natural Science Foundation of China, No. 81572199, No. 81472140

Abstract:

BACKGROUND: Epidemiologic reports have indicated that excessive weight-bearing exercise is one of important risk factors for lumbar degeneration, but the effects of weight-bearing activity on normal lumbar motion pattern are still not clear.
OBJECTIVE: To measure the changing characteristics and rules of position at the center of rotation of the lower lumbar spine during a weight-lifting activity of normal person.
METHODS: Fourteen asymptomatic subjects with a mean age of (25±5) years were recruited for this study. The L4-5 and L5-S1 segments of each subject were CT-scanned to construct 3D models using dual X-ray imaging system and spiral CT examination combined technology in the aid of computer software. The physiological load and lumbar spinal 3D motion under the loading condition were reproduced when matching the flexion, neutrality and extension in the dual X-ray imaging system and on dual oblique lumbar X-ray image. Coordinate systems were established at the vertebral body of L4-S1 to obtain the center of rotation during flexion-to-neutral, neutral-to-extension and the full flexion-extension motion.
RESULTS AND CONCLUSION: (1) Under physiological load, the center of rotation of L4-5 of normal person was located about 1.0 mm anterior to the central axis of the vertebral body, and the center of rotation of L5-S1 was located about 0.7 mm anterior to the central axis of the vertebral body. (2) With weight loading, the center of rotation of both two segments shifted backward about 0.5 mm. There was no statistical difference between these two loading conditions. (3) When the center of rotation in flexion and extension was calculated respectively, the moving range of the center of rotation at both L4-5 and L5-S1 became larger due to taking loads of 10 kg (P < 0.05). In flexion, the center of rotation at L5-S1 significantly shifted forward during a weight-lifting activity (P < 0.05). (4) These results confirm that compared with non-weight-bearing condition, the trajectory of the center of rotation was found to be increased when taking loads, especially during the flexion-to-neutral motion.