No abstract

In this study, we constructed a novel three-dimensional trunk musculoskeletal model that included thoracolumbar intervertebral using data from computed tomography (CT) and magnetic resonance imaging (MRI). Characteristics of the model are as follows. Firstly, the thoracolumbar structure was modeled in detail (i.e., skeleton，muscle paths and muscle cross-section areas) from CT and MRI data. Secondly, new factors were included in this model such as intra-abdominal pressure and physiological trunk range of motion to calculate internal biological forces more accurately than in previous models. Thirdly, this musculoskeletal trunk model is an aid to analyzing dynamic motion. The aims of this study was to analyze detailed three-dimensional motion in healthy adults using this model, and to estimate internal biological forces, including spinal moment and muscle force in a standing position. The validation of this model used the calculated intradiscal pressure for the L4/L5 disc according to previous reports. This model is able to analyze spinal moments and trunk muscle force during static motions. The present study confirms that the moment curve of spinal can be generalized in the various postures. The model has been validated, and was able to analyze three-dimensional motion (i.e., combinational factors of rotation and flexion). As a result, this model is expected to have clinical applications.

The restoration of motor functions of patients with spinal cord injury (SCI) is one of important subjects for study. For this purpose, methods of functional neuromuscular stimulation (FNS) have been investigated in medical science and practice during these three decades. However, we have not achieved complete restoration of motor functions in SCI patients. On the other hand, we have achieved useful devices in human-scaled transportation by using power assist technology. Thus, applying power assist technology to the problem of restoring motor functions is one of possible solutions and sounds practical. In this paper, we propose a new hybrid system to combine power assist technology and FNS for restoring motor functions of lower extremity in SCI patients. Both powered orthosis and FNS are used to generate and control the joints moments of lower extremity in the proposed hybrid system. The main role of powered orthosis to compensate the joints moments generated by FNS and to enhance the controllability of FNS with the actuators. The proposed hybrid control system has been experimentally evaluated in gait motions by measuring the angle trajectories and generated moments around the knee and hip joints in the cases when only actuators are used and both FNS and actuators of the orthosis are used. The results prove that the control method for the hybrid system is useful to restore motor functions of lower extremity in SCI patients.

We developed novel trunk musculoskeletal models with detailed muscle paths for predicting the thoracolumbar load, and validated the developed models under dynamic loading and various postures. Two types of musculoskeletal models with different paths of the trunk muscles were constructed: a Via-Point type (with linear muscles) and Wrapping type (with curved muscles along ellipsoids). We predicted the intradiscal pressure (IDP) with the models and compared the results with literature values. The IDP predicted using the wrapping-type model had an extremely strong correlation with IDP measurements from the thoracic spine. The results demonstrate the effectiveness of more accurate muscle paths in musculoskeletal models for predicting the thoracolumbar load.

This paper presents an adaptive simulator for a manual wheelchair to reduce the user's upper limb load during wheelchair manipulation and to increase the efficiency of wheelchair propulsion. The proposed simulator provides an optimal position of the handrim/lever and the desired angular position of the seat and backrest of the wheelchair based on the user's body function.