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The consensus of the normal magnitude of lumbosacral curve has not been achieved. The Cobb's angle cannot depict the whole contour of this curve. For practical applications, a clearer image of these curves and their aging changes should be further investigated. This study aimed to provide a more consolidate concept of normal lumbosacral curves for clinician through a computerized reconstruction method.

Standing lateral radiographs of lumbosacral spine in 82 normal adults were used for reconstructing the sagittal lumbosacral curves. The geometric characteristics of these curves according to the gender and age groups were studied. Using standing lateral radiographs, reconstruction of the lumbosacral curves was performed through digitization, programming and computation. These curves and related parameters were normalized and averaged for analyzing the differences of gender and age.

The most anteriorward and horizontal vertebrae usually occurred on the L4 and L3 in any gender and age groups. The sacral inclination angle did not change obviously with the increasing ages. A tendency of L1 shifting backward was noted in the age groups of 40 to 60 and above 60 years old. The sagittal lumbosacral curves can be easily reconstructed by digitizing lateral radiographs, The aging changes of lumbosacral curves could be qualitatively described as the flattening of lower lumbar curve and the rearward inclination of upper lumbar curve. The changes occurred obviously above 40 years old. Although individual variations existed, the aging changes and the geometric characteristics such as the most anteriorward or horizontal vertebrae could be used as an important guideline during therapy or surgical correction.

This study investigated center-of-pressure (COP) characteristics during volitional stepping in forward, backward, and sideways directions, along with the behavioral performance measures and COP measures of volitional stepping in these directions, and the relationships between these two types of measures in healthy older and young adults. Fifteen older and 15 young adults performed rapid stepping in the three directions using each leg. Behavioral performance measures included reaction time (RT), movement time (MT), step length, and step velocity in the MT phase. COP measures included the maximum anteroposterior (COP_AP) and mediolateral COP displacement (COP_ML) in the RT phase. Stepping in each direction demonstrated unique COP characteristics. The older adults presented slower RT, MT, step velocity, and smaller COP_AP in all three stepping directions (p < 0.05), as well as smaller COP_ML in the sideways stepping direction (p < 0.017), compared to the young adults. Step velocity correlated with COP_AP and/or COP_ML in all three stepping directions for both groups (r = 0.42–0.77, p < 0.05), suggesting that stepping performances during the movement execution phase correlated with COP control during the postural preparation phase. Results suggest that stepping training prescribed to older adults to improve their balance control may include multi-directional stepping.

The degeneration of sensory and motor systems due to aging could affect the elderly’s posture and increase the risk of falling. The strategies applied to maintain postural stability might be different between ages, especially in the condition requiring both proprioception and vision sensorimotor coupling. This study proposed a novel sensorimotor assessment protocol to evaluate the postural control ability across the aging process, by using the computerized dynamic posturography and the virtual reality (VR) system. Ten young and 20 elderly healthy adults without fall experience were recruited, and were assessed on a continuous-perturbed platform with or without the VR-based visual interference in a random sequence. Measured variables of the center of pressure as well as the weight-bearing ratio were analyzed and compared. Results showed that the postural sway was significantly larger in all subjects under the VR condition, but the young subjects could rapidly adjust the body to regain postural stability in a rhythmic and symmetric manner; whereas, the elderly adults performed less effectively in postural response. We suggested that the application of the multiple sensation disturbances with VR could effectively evaluate the postural control ability among the healthy elderly. The proposed assessing protocol is also recommended for training the sensorimotor integration to improve the dynamic postural control ability.