In this paper, we generated finite element (FE) models to predict the contact pressure between a foam mattress and the human body in a supine position. Twenty-year-old males were used for three-dimensional scanning to produce the FE human models, which was composed of skin and muscle tissue. A linear elastic isotropic material model was used for the skin, and the Mooney-Rivlin model was used for the muscle tissue because it can effectively represent the nonlinear behavior of muscle. The contact pressure between the human model and the mattress was predicted by numerical simulation. The human models were validated by comparing the body pressure distribution obtained from the same human subject when he was lying on two different mattress types. The experimental results showed that the slope of the lower part of the mattress caused a decrease in the contact pressure at the heels, and the effect of bone structure was most pronounced in the scapula. After inserting a simple structure to function as the scapula, the contact pressure predicted by the FE human models was consistent with the experimental body pressure distribution for all body parts. These results suggest that the models proposed in this paper will be useful to researchers and designers of products related to the prevention of pressure ulcers.

PurposePoor recovery of postural stability poststroke is the primary cause of impairment in activities and social participation in elderly stroke survivors. The purpose of our study was to experimentally evaluate the effectiveness of our new elastic ankle–foot orthosis (AFO), compared to a traditional AFO fabricated with hard plastic, in improving postural stability in elderly chronic stroke survivors.Patients and methodsPostural stability was evaluated in ten chronic stroke patients, 55.7±8.43 years old. Postural stability was evaluated using the standardized methods of the Biodex Balance System combined with a foot pressure system, under three experimental conditions, no AFO, rigid plastic AFO, and elastic AFO (E-AFO). The following dependent variables of postural stability were analyzed: plantar pressure under the paretic and nonparetic foot, area of the center of balance (COB) and % time spent in each location, distance traveled by the COB away from the body center, distance traveled by the center of pressure, and calculated index of overall stability, as well as indices anterior–posterior and medial–lateral stability.ResultsBoth AFO designs improved all indices of postural stability. Compared to the rigid plastic AFO, the E-AFO produced additional positive effects in controlling anterior–posterior body sway, equalizing weight bearing through the paretic and nonparetic limbs, and restraining the displacement of the center of pressure and of the COB.ConclusionBased on our outcomes, we recommend the prescription of E-AFOs as part of a physiotherapy rehabilitation program to promote recovery of postural stability poststroke. When possible, therapeutic outcomes should be documented using the Biodex Balance System and foot pressure system, as used in our study, to provide evidence needed to support the development of a larger controlled trial to generate high-quality evidence on the effectiveness of E-AFOs.

PurposeThe post-stroke elderly was increased caused by increasing stroke and advanced medical. However, ankle–foot orthoses (AFOs) can be uncomfortable for hemiplegic patients; therefore, the usability is not good. In this study, we analyzed ankle and knee joint angles in post-stroke elderly patients to assess the functional effectiveness (specifically prevention of back knee and drop-foot) of a new elastic band-type AFO (New Product: NP) during gait.Patients and methodsNine elderly post-stroke patients (eight males, one female; 55.7±8.4 years; 165.8±9.2 cm; 68.8±11.5 kg; five with right hemiplegia, four with left hemiplegia; onset period: 6.6 years) were selected for participation in this study. We captured gait motion using 12 cameras (MX-T20, Vicon, Inc., Oxford, UK) under three different conditions [wearing nothing (WI), using existing ordinary AFOs made from hard plastic material (EP), and using NP]. The angle variation and maximum–minimum angle of the lower body joints were analyzed during dorsi-plantar flexion of the ankle joint and flexion–extension of knee joint. A one-way ANOVA test for multiple comparisons was performed, followed by a Tukey’s b test to identify statistical significance, which was set at 0.005.ResultsRegarding the ankle joint, the maximum plantar flexion (drop-foot) value decreased with the NP, and the maximum dorsiflexion value increased. Regarding the knee joint, the maximum extension (back knee) value decreased, and the maximum flexion value increased (p < 0.005).ConclusionUsing analysis of the kinematics of the ankles and knees during walking, this research confirmed the effectiveness of the NP, an elastic band-type AFO, for use in ordinary post-stroke elderly patients.

Objective: The aim of this study is to investigate the effects of trunk-forearm supported sitting on trunk flexion angle, trunk extensor fatigue and seat contact pressure. Background:The relationship between sitting posture and musculoskeletal disorders of the trunk extensor fatigue and seat contact pressure has been documented. The trunk-forearm support type ergonomic chair was devised from the fact that trunkforearm support has been reported to reduce trunk extensor activity and discomfort.Method: Using three different sitting postures, upright (P1), trunk-forearm supported (P2) and normal sitting (P3), six healthy subjects participated in the study. Motion capture system was used to collect head and trunk flexion angle, and surface electromyography (sEMG) was used to collect myoelectric signal of upper trapezius, lower trapezius, erector spinae, multifidus, and pressure mat system was used to measure seat contact pressure.Results: When trunk and forearm were supported by the ergonomic chair, higher head flexion angle showed upright > trunk-forearm supported > normal in order, and muscle fatigue showed less than upright and normal sitting. Mean seat contact pressure decreased 19% than upright sitting. But muscle fatigue was not affected by each condition. Conclusion:Trunk-forearm supported sitting of the ergonomic chair showed positive effect in respect of trunk and head flexion angle, trunk extensor fatigue, seat contact pressure. To acquire comprehensive understanding of the effectiveness of the ergonomic chair, further studies such as anatomical effects from measurement of external applied loading effect to the body from interface pressure analysis are required. Application:The results of the publishing trend analysis might help physiological effects of trunk-forearm support type chair.