Postural instability is prevalent in aging and neurodegenerative disease, decreasing quality of life and independence. Quantitatively monitoring balance control is important for assessing treatment efficacy and rehabilitation progress. However, existing technologies for assessing postural sway are complex and expensive, limiting their widespread utility. Here, we propose a monocular imaging system capable of assessing sub-millimeter 3D sway dynamics during quiet standing. Two anatomical targets with known feature geometries were placed on the lumbar and shoulder. Upper and lower trunk 3D kinematic motion were automatically assessed from a set of 2D frames through geometric feature tracking and an inverse motion model. Sway was tracked in 3D and compared between control and hypoperfusion conditions in 14 healthy young adults. The proposed system demonstrated high agreement with a commercial motion capture system (error 1.5×10−4mm1.5 \times 10^{-4}\,\,\text {mm} , [−0.52, 0.52]). Between-condition differences in sway dynamics were observed in anterior-posterior sway during early and mid stance, and medial-lateral sway during mid stance commensurate with decreased cerebral perfusion, followed by recovered sway dynamics during late stance with cerebral perfusion recovery. This inexpensive single-camera system enables quantitative 3D sway monitoring for assessing neuromuscular balance control in weakly constrained environments.

中文翻译：

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单目 3D 摇摆跟踪用于评估安静站立期间脑灌注不足的姿势不稳定性


姿势不稳定在衰老和神经退行性疾病中普遍存在，降低了生活质量和独立性。定量监测平衡控制对于评估治疗效果和康复进展非常重要。然而，现有的评估姿势摇摆的技术复杂且昂贵，限制了其广泛应用。在这里，我们提出了一种单目成像系统，能够评估安静站立时的亚毫米 3D 摇摆动态。两个具有已知特征几何形状的解剖目标被放置在腰部和肩部。通过几何特征跟踪和逆运动模型，从一组 2D 帧自动评估上下躯干 3D 运动。对 14 名健康年轻人的摇摆进行了 3D 跟踪，并在对照和低灌注条件下进行了比较。所提出的系统与商业运动捕捉系统表现出高度一致性（误差 1.5×10−4mm1.5 \times 10^{-4}\,\,\text {mm} , [−0.52, 0.52]）。在站立早期和中期的前后摇摆以及站立中期的内侧-外侧摇摆中观察到摇摆动力学的条件间差异，这与脑灌注减少相称，随后随着脑灌注恢复，在站立后期的摇摆动力学恢复。这种廉价的单摄像头系统可实现定量 3D 摇摆监测，以评估弱约束环境中的神经肌肉平衡控制。