Research & Surveillance Division, Extremity Trauma and Amputation Center of Excellence, Defense Health Agency, Falls Church, VA 22042, United States; Department of Rehabilitation, Walter Reed National Military Medical Center, Bethesda, MD 20889, United States; Department of Physical Medicine & Rehabilitation, Uniformed Services University of the Health Sciences, Bethesda, MD 20814, United States.
Research & Surveillance Division, Extremity Trauma and Amputation Center of Excellence, Defense Health Agency, Falls Church, VA 22042, United States; Department of Physical & Occupational Therapy, Naval Medical Center, San Diego, CA 92134, United States.
J Biomech. 2023 Sep;158:111768. doi: 10.1016/j.jbiomech.2023.111768. Epub 2023 Aug 17.
Standing sway assessments can detect sensory imbalances which compromise postural control. Persons with lower limb amputation (LLA) often demonstrate impaired postural control, increasing fall risk. Here, principal features of postural sway were identified in persons with unilateral LLA using a single, commercially available wearable sensor. Sixty-one persons with LLA (n = 44 transtibial; n = 17 transfemoral) stood on a firm surface with eyes open/closed while wearing a single accelerometer mounted over the sacrum. Common parameters quantified spatiotemporal and spectral features of sway in anterior-posterior (AP) and mediolateral (ML) directions. Principal component (PC) dimensionality reduction was applied and loadings inspected to identify a reduced, non-redundant set among 14 original variables capturing 90 % variance. Six PCs described ≥ 90 % variance, with the first 3 explaining 75 %. With eyes open and closed, PC1 was loaded by variables characterizing trajectory planar size: area, jerk (i.e., sway smoothness), AP/ML RMS path distance, and AP/ML path range. With eyes open, PC2 was loaded by variables characterizing direction and spectral features: ellipse rotation, AP centroidal frequency, and ML jerk. With eyes closed, PC2 spectral loadings increased: ML centroidal frequency, ML frequency dispersion, and AP centroidal frequency. With eyes open, PC3 was loaded by ellipse rotation, jerk, ML velocity, ML centroidal frequency. With eyes closed, PC3 was loaded by ellipse rotation, ML centroidal frequency, ML frequency dispersion, and AP path velocity, characterizing off-axis error/corrections. RMS of path distance, ellipse rotation, centroidal frequency, frequency dispersion, path velocity, and jerk are a concise parameter set, derived from an accelerometer, to capture principal sway features in persons with LLA during standing balance with visual perturbations.
站立摆动评估可以检测到影响姿势控制的感觉失衡。下肢截肢（LLA）患者通常表现出姿势控制受损，增加了跌倒风险。在这里，使用单个商业可用的可穿戴传感器，在单侧 LLA 患者中确定了姿势摆动的主要特征。61 名 LLA 患者（n=44 胫骨；n=17 股骨）在睁眼/闭眼时站在坚硬的表面上，同时在骶骨上佩戴单个加速度计。常用参数量化了前后（AP）和内外（ML）方向的摆动空间和频谱特征。应用主成分（PC）降维，并检查加载以在捕获 90%方差的 14 个原始变量中识别一组减少的、非冗余的变量。前 6 个 PC 描述了≥90%的方差，前 3 个解释了 75%。睁眼和闭眼时，PC1 由轨迹平面大小的变量加载：面积、急动度（即摆动平滑度）、AP/ML RMS 路径距离和 AP/ML 路径范围。睁眼时，PC2 由方向和频谱特征的变量加载：椭圆旋转、AP 质心频率和 ML 急动度。闭眼时，PC2 频谱负荷增加：ML 质心频率、ML 频率分散和 AP 质心频率。睁眼时，PC3 由椭圆旋转、急动度、ML 速度、ML 质心频率加载。闭眼时，PC3 由椭圆旋转、ML 质心频率、ML 频率分散和 AP 路径速度加载，这些特征表征了偏轴误差/校正。路径距离、椭圆旋转、质心频率、频率分散、路径速度和急动度的 RMS 是一个简洁的参数集，它来自于加速度计，用于捕获站立平衡期间视觉干扰下 LLA 患者的主要摆动特征。
