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. 2021 Jun;49(6):3000605211020219.
doi: 10.1177/03000605211020219.

Upper and lower adjacent segment range of motion after fixation of different lumbar spine segments in the goat: an in vitro experiment

Yufu Ou  1   2 , Zengming Xiao  1 , Jianxun Wei  2 , Hua Jiang  1 , Zhuhai Li  2
Affiliations

Upper and lower adjacent segment range of motion after fixation of different lumbar spine segments in the goat: an in vitro experiment

Yufu Ou et al. J Int Med Res. 2021 Jun.

Abstract

Objectives: The purpose of this study was to examine the biomechanical effects of fixation on range of motion (ROM) in the upper and lower adjacent segments of different lumbar spine segments in a goat spine model.

Methods: Fifteen goat spine specimens (vertebrae T12-S1) were randomly divided into three groups: A (single-segment fixation), B (double-segment fixation), and C (triple-segment fixation). Motion in different directions was tested using a spinal motion simulation test system with five external loading forces. Transverse, forward-backward, and vertical displacement of the upper and lower adjacent segments were measured.

Results: As the external load increased, the upper and lower adjacent segment ROM increased. A significantly greater ROM in group C compared with group A was found when the applied external force was greater than 75 N. The upper adjacent segment showed a significantly greater ROM than the lower adjacent segment ROM within each group.

Conclusions: Adjacent segment ROM increased with an increasing number of fixed lumbar segments. The upper adjacent segment ROM was greater than that of the lower adjacent segments. Adjacent segment stability after lumbar internal fixation worsened with an increasing number of fixed segments.

Keywords: Adjacent segment degeneration; biomechanics; fixed segment; lumbar internal fixation; lumbar vertebrae; range of motion.

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Conflict of interest statement

Declaration of conflicting interest: The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Figures

Figure 1.
Figure 1.
Main experimental equipment.
Figure 2.
Figure 2.
Successful specimen model and its X-ray imaging.
Figure 3.
Figure 3.
Schematic diagram of the coordinates of the ball movement.
Figure 4.
Figure 4.
Plan view and 3D view of the displacement of the ball.
Figure 5.
Figure 5.
Left view of the ball/3D displacement schematic diagram/Right view of the ball.
Figure 6.
Figure 6.
Measurement results of transverse displacement, forward?backward displacement, and vertical displacement in lateral motion; A1, B1 and C1 represent the upper adjacent segments; A2, B2 and C2 represent the lower adjacent segments. TD, transverse displacement; FD, forward?backward displacement; VD, vertical displacement.
Figure 7.
Figure 7.
Measurement results of transverse displacement, forward?backward displacement, and vertical displacement in backward extension; A1, B1 and C1 represent the upper adjacent segments; A2, B2 and C2 represent the lower adjacent segments.TD, transverse displacement; FD, forward?backward displacement; VD, vertical displacement.
Figure 8.
Figure 8.
Measurement results of transverse displacement, forward?backward displacement, and vertical displacement in anteflexion motion; A1, B1 and C1 represent the upper adjacent segments; A2, B2 and C2 represent the lower adjacent segments.TD, transverse displacement; FD, forward?backward displacement; VD, vertical displacement.
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