Climbing stairs can become a daily obstacle for elderly people, and an exoskeleton can assist here. However, the exoskeletons that are designed to assist stair climbing are actuated in different ways. To find a minimal actuation configuration, we identify the assist phases by evaluating the power deficit of 11 healthy but weak elderly people (72.4 ± 2.1 years; 69–76 years; 1.67 ± 0.10 m; 74.88 ± 14.54 kg) compared to 13 younger people (24.0 ± 1.8 years; 22–28 years; 1.74 ± 0.10 m; 70.85 ± 11.91 kg) in a biomechanical study and discuss moment characteristics. Three-dimensional kinematics and ground reaction forces were collected, and kinematics, kinetics, and power characteristics of each subject for ascent and descent were calculated using inverse dynamics. Significant differences for power between both groups were assessed with statistical parametric mapping method using dynamic time warping. During ascent, the largest significant power deficit of the elderly subjects occurs in the single stance phase (SSP) during pull-up in the knee joint. During descent, significant mean power deficits of 0.2 and 0.8 W/kg for the highest deficit occur in the ankle joint in the beginning of the SSP and also in the knee joint in the same phase. Therefore, an exoskeleton should address the power deficit for knee extension (ascent: 1.0 ± 0.9 W/kg; descent: 0.3 ± 0.2 W/kg) and could assist the ankle during ascent and descent by an additional plantar flexion moment of 0.2 Nm/kg each.

Ankle inversion is a common injury of musculoskeletal system among athletes and also in the older population. Investigation into ankle inversion requires quantitative assessment of the smallest amount of height/angle change in the floor that can be perceived by human. Blocks of different thickness have been used to change floor height manually during tests. We aimed to develop an automatic apparatus that is able to provide improved height and angle resolutions for dynamic ankle proprioception. We designed and manufactured a five-bar planar robot with one coupler serving as the mobile platform. We used a stiffening rib to achieve consistent differences in deflection across the workspace of the mobile platform. The reported robot translates at the maximal speed 423 mm/s with a resolution at 0.21 mm under a maximal load of 358 kg. This robot allows for increased sensitivity, which may lead to further investigation of functional proprioceptive ability and reflect finely tuned sensory requirements for upright stance.

Objective: Submissions on recovery of post-stroke motor performance vary, especially in relation to increasing time after stroke. This study examined the trajectory of motor performance over the first 12 months after stroke.

Methods: Consecutive first-incidence stroke survivors (N = 83) were recruited within 1 month of onset from a tertiary health institution in Nigeria. Simplified Fugl Meyer scale (S-FM) was used to assess motor performance at monthly intervals. Changes in overall motor performance, and differences between the affected upper and lower extremities, were examined using Friedman's ANOVA and paired t-tests, respectively.

Results: Significant improvement in motor performance was observed across 12 months (p < .001), with the proportion of stroke survivors with severe impairment at onset (53.3%) decreasing to 20% by 12 months. Lower extremity motor performance scores were significantly higher than for the upper extremity from 1 to 12 months (p <.01 at 3, 4, 5, 6 and 12 months; and p < .05 at the remaining months).

Conclusions: The potential for long-term improvement in motor performance after stroke was observed, suggesting that this can be harnessed by long-term rehabilitation efforts. The comparatively poorer outcome in the upper extremity indicates the need for extra rehabilitation strategies to enhance upper-extremity motor recovery in the first year of stroke.

Several lines of evidence suggest that mental motor imagery is subserved by the same cognitive operations and brain structures that underlie action. Additionally, motor imagery is informed by the anticipated sensory consequences of action, including pain. We reasoned that motor imagery could provide a useful measure of chronic leg or foot pain. Forty subjects with leg pain (19 bilateral, 11 right, and 10 left leg pain), 42 subjects with chronic pain not involving the legs, and 38 controls were shown 12 different line drawings of the right or left foot and asked to indicate which foot was depicted. Previous work suggests that subjects perform this task by mentally rotating their foot to match the visually presented stimulus. All groups of subjects were slower and less accurate with stimuli that required a greater degree of mental rotation of their foot. Subjects with leg pain were both slower and less accurate than normal and pain control subjects in responding to drawings of a painful extremity. Furthermore, subjects with leg pain exhibited a significantly greater decrement in performance for stimuli that required larger amplitude mental rotations. These data suggest that motor imagery may provide important insights into the nature of the pain experience. (JINS, 2010, 16, 603–612.)

Knowledge of the control of the musculoskeletal system in patients with knee osteoarthritis (OA) during gait is helpful for the development of intervention programs in the management of these patients. The current study aimed to investigate the leg and joint stiffness, aswell as the associated joint kinematics and kinetics, in patients with bilateral medial knee OA during gait. Joint angles, moments and stiffness, as well as leg stiffness from fifteen patients with bilateral knee OA and fifteen normal controls during level walking, were obtained and their values at the beginning and end of single leg stance were compared using a t-test.

Patients with knee OA were found to modulate their leg and joint stiffness through acquired specific biomechanical strategies in order to maintain normal temporal-spatial patterns of gait. During weight acceptance, they increased their leg stiffness with increased knee stiffness but unalterd hip and ankle stiffness. During weight release, they modulated their hip and ankle kinetics with increased knee and ankle stiffness to improve the control stability of the limb with unaltered leg stiffness. It is suggested that muscle strengthening exercise intervention and/or rehabilitation for patients with knee OA should focus on activities that develop and/or maintain functions not only of the knee, but also of the overall lower extremity.