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Diabetic heel ulceration, a serious, destructive, and costly complication of diabetes, is often treated by custom-made offloading footwear. One common offloading device is a custom-made insole designed with a hole under the damaged site that is intended to reduce local mechanical loads on the ulcer. However, current devices do not take into account the increasing loads at the wound peripheries, and quantitative assessments and scientific guidelines for the optimal design of the offloading hole are lacking. Here, we develop a novel method to determine the volumetric exposure to mechanical loading of a human heel, at two volume of interests (VOIs) during walking in 150 different finite-element footwear configurations. We defined the two VOIs as (1) the area of the heel soft tissues typically at high risk of ulceration, and (2) the soft tissues surrounding the high risk area. For all model variants, three hole-geometry parameters were defined: (1) radius, (2) radius of curvature (ROC) and (3) depth. We found two combinations of the offloading parameters which minimize heel loads in both VOIs. The first is with a large offloading radius, large ROC and large depth, whereas the second is with a large offloading radius, large depth but relatively small ROC. Our novel practical scientific analysis method, that takes into account the ulcer site as well as the peripheral area, has the potential to optimize development of offloading solutions by streamlining the examination of their biomechanical efficiency, and thus may revolutionize prevention and treatment of diabetic ulcers at any foot location.

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OBJECTIVE: To evaluate the effect of 15° forward (FW) seat inclination and foot-support in children with cerebral palsy (CP) on postural adjustments during reaching. DESIGN: Observational study repeated-measures design; step two of two-step-project. SETTING: Laboratory unit within University Hospital and two special education schools. PARTICIPANTS: 19 children (ten unilateral spastic CP (US-CP); nine bilateral spastic CP (BS-CP); Gross Motor Function Classification System levels I-III; 6-12 years old). Participants were able to take part for one one-hour session. INTERVENTION: Reaching while sitting in four seating conditions (FW or horizontal seat; with or without foot-support) applied in randomized order. OUTCOME MEASURES: Simultaneously, surface electromyography (EMG) of neck, trunk and arm muscles and kinematics of head and reaching arm (step one of two-step-project) were recorded. Primary outcome parameters were the ability to modulate EMG-amplitudes at baseline and during reaching (phasic muscle activity). Other EMG-parameters were direction-specificity (1st control level), and 2nd level of control parameters: recruitment order, and anticipatory postural activity. Motor behaviour measures: ability to modulate EMG-amplitudes to kinematic characteristics of reaching and head stability. RESULTS: Only foot-support was associated with increased tonic background EMG-amplitudes and decreased phasic EMG-amplitudes of the trunk extensors in children with US-CP and BS-CP (mixed-models analyses; p-values <0.01). The foot-support effect was also associated with better kinematics of reaching (Spearman's Rho; p-values <0.01). CONCLUSION: In terms of postural adjustments during forward reaching, foot-support enhanced the children's capacity to modulate trunk extensor activity, which was associated with improved reaching quality. FW-tilting did not affect postural muscle activity.

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BACKGROUND: The effect of forward-tilting of the seat surface and foot-support in children with spastic cerebral palsy (CP) is debated. AIM: To assess the effect of forward-tilting of the seat surface and foot-support in children with CP on kinematic head stability and reaching. METHODS: Nineteen children functioning at Gross Motor Function Classification System levels I-III participated [range 6-12y; ten unilateral spastic CP (US-CP) and nine bilateral spastic CP (BS-CP)]. Kinematic data were recorded of head sway and reaching with the dominant arm in four sitting conditions: a horizontal and a 15° forward (FW) tilted seat surface, each with and without foot-support. RESULTS: Seating condition did not affect head stability during reaching, but did affect kinematic reaching quality. The major reaching parameters, i.e., the proportion of reaches with one movement unit (MU) and the size of the transport MU, were not affected by foot-support. Forward-tilting had a positive effect on these parameters in children with US-CP, whereas the horizontal condition had this effect in children with BS-CP. IMPLICATIONS: A 15° forward-tilted seating and foot-support do not affect head stability. Reaching in children with US-CP profits from forward-tilting; in children with BS-CP forward-tilting worsens reaching - effects that are independent of foot-support.

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[Purpose] The mechanical strength of wheelchair and seating products is specified by standards to ensure user safety. However, some individual users are affected by severe spasticity resulting from cerebral palsy that occasionally breaks such devices. Until recently, reports of quantitative measurement of these mechanical overloads have been scarce, and the exact loads applied have been unknown. This study aimed to conduct a sampling survey prior to conducting a future full-scale study. [Subjects and Methods] Using two force plates, we measured the load on the foot support applied by three participants with cerebral palsy. The applied load was measured at a 100 Hz sampling rate, and maximum load and vertical/horizontal component forces were analyzed. [Results] The maximum load applied by participants was approximately 1.34 times their body weight. The vertical force applied on the foot support accounted for 70-80% of the total load. The horizontal force also reached about 35% at its maximum. [Conclusion] Because the horizontal load also reached 1/3 of the total load, it will be advantageous to use a three-axis force plate to measure forces in a future study with more participants.

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BACKGROUND: Individuals with cervical spinal cord injury usually sustain impairments to the trunk and upper and lower limbs, resulting in compromised sitting balance. The objectives of this study were to: 1) compare postural control of individuals with cervical spinal cord injury and able-bodied individuals; and 2) investigate the effects of foot support and trunk fluctuations on postural control during sitting balance. METHODS: Ten able-bodied individuals and six individuals with cervical spinal cord injury were asked to sit quietly during two 60s trials. The forces exerted on the seat and the foot support surfaces were measured separately using two force plates. The global centre of pressure sway was obtained from the measurements on the two force plates, and the sway for each force plate was calculated individually. FINDINGS: Individuals with spinal cord injury had at least twice as large global and seat sways compared to able-bodied individuals, while foot support sway was not significantly different between the two groups. Comparison between global and seat sways showed that anterior-posterior velocity of global sway was larger compared to the seat sway in both groups. INTERPRETATION: Postural control of individuals with cervical spinal cord injury was worse than that of able-bodied individuals. The trunk swayed more in individuals with spinal cord injury, while the stabilization effect of the feet did not differ between the groups. Foot support affected anterior-posterior fluctuations in both groups equally. Thus, trunk control is the dominant mechanism contributing to sitting balance in both able-bodied and spinal cord injury individuals.

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