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So far, there have been no high-quality studies examining the efficacy of outpatient biofeedback devices in cases of prescribed partial weight-bearing, such as after surgery on the lower limbs. This study aimed to assess whether a biofeedback device is more effective than using a personal scale. Two groups of healthy individuals wearing an insole orthosis were trained to achieve partial loading in a three-point gait within a target zone of 15–30 kg during overground walking and going up and down stairs. The treatment group (20 women and 22 men) received continuous biofeedback, while the control group (26 women and 16 men) received no information. Findings were compared in a randomized controlled trial. Compliance with partial loading without biofeedback was poor; on level ground and stairs, only one in two steps fell within the target area, and overloading occurred on at least one in three steps. The treatment group reduced the percentage of steps taken in the overload zone to ≤8.4% (p < 0.001 across all three courses) and achieved more than two-thirds of their steps within the target zone (p < 0.001 on level ground, p = 0.008 upstairs, and p = 0.028 downstairs). In contrast, the control group did not demonstrate any significant differences in the target zone (p = 0.571 on level ground, p = 0.332 upstairs, and p = 0.392 downstairs). In terms of maintaining partial load, outpatient biofeedback systems outperform bathroom scales.

Abstract Background Partial weight bearing in an orthosis and with forearm crutches is a widespread and well-accepted therapeutic principle after an injury of the lower extremity during early rehabilitation. Complying may be challenging to do under these circumstances, especially for elderly people. This study compares the spatiotemporal parameters and peak loads performed by a group of older participants before and after activating real-time biofeedback (BF) to determine whether they benefit from a biofeedback. Methods Twenty-four healthy subjects between 61 and 80 years learned how to walk using forearm crutches in a lower leg orthosis while performing a weight of 20 kg using a bathroom scale with the aim of loading in a zone between 15 and 30 kg. After that, they completed a course that was on level ground (50 m) and another course on stairs (11 steps). They did a walk without BF first, and then with BF. Each step was given a maximum load, which was determined and statistically checked. In addition, spatiotemporal parameters were collected. Results The classical teaching method with a bathroom scale was ineffective. Only 32.3% of the loads could be adequately carried by a person on level ground in the 15–30 kg target zone. On the stairs, it was 48.2% and 34.3%, respectively. Thus, on level ground, 52.7% of loads exceeded 30 kg. Downstairs it was 46.4%, and upstairs it was 41.6%. Subjects clearly benefit from activated biofeedback. Biofeedback significantly reduced missteps > 30 kg in every course. The loads decreased significantly to 25.0% on level ground, to 23.0% upstairs, and to 24.4% downstairs. At the same time, speed and stride length decreased per course while total time increased. Conclusion Partial weight bearing is more complex and difficult for the elderly. These study results may help better understand 3-point gait in older adults in an outpatient setting. When partial weight bearing is recommended, special follow-up attention must be given for this group. Age-based therapy strategies can be developed and monitored with the assistance of ambulatory biofeedback devices. Trial registration Retrospectively registered, https://www.drks.de/DRKS00031136 .

Magnetic nanoparticles (MNPs) can be functionalized with antibodies to give them an affinity for a biomarker of interest. Functionalized MNPs (fMNPs) cluster in the presence of a multivalent target, causing a change in their magnetization. Target concentration can be proportional to the 3rd harmonic phase of the fMNP magnetization signal. fMNP clustering can also be induced with salt. Generally, salt can alter the stability of charge stabilized fMNPs causing a change in magnetization that is not proportional to the target concentration. We have developed a model system consisting of biotinylated MNPs (biotin-MNPs) that target streptavidin to study the effects of salt concentration on fMNP-based biosensing in simulated in vivo conditions. We have found that biotin-MNP streptavidin targeting was independent of salt concentration for 0.005x to 1.00x phosphate buffered saline (PBS) solutions. Additionally, we show that our biosensor’s measurable concentration range (dynamic range) can be tuned with biotin density. Our results can be leveraged to design an in vivo nanoparticle (NP)-based biosensor with enhanced efficacy in the event of varying salt concentrations.

Background: The aim of this study was to assess the phenotype of multifocal motor neuropathy (MMN) and amyotrophic lateral sclerosis (ALS) in quantitative MR neurography. Methods: In this prospective study, 22 patients with ALS, 8 patients with MMN, and 10 healthy volunteers were examined with 3T MR neurography, using a high-resolution fat-saturated T2-weighted sequence, diffusion-tensor imaging (DTI), and a multi-echo T2-relaxometry sequence. The quantitative biomarkers fractional anisotropy (FA), radial and axial diffusivity (RD, AD), mean diffusivity (MD), cross-sectional area (CSA), T2-relaxation time, and proton spin density (PSD) were measured in the tibial nerve at the thigh and calf, and in the median, radial, and ulnar nerves at the mid-upper arm. Results: MMN showed a characteristic imaging pattern of decreased FA (p = 0.018), increased RD (p = 0.014), increased CSA (p < 0.001), increased T2-relaxation time (p < 0.001), and increased PSD (p = 0.025) in the upper arm nerves compared to ALS and controls. ALS patients did not differ from controls in any imaging marker, nor were there any group differences in the tibial nerve (p > 0.05). Conclusions: MMN shows a characteristic pattern of quantitative DTI and T2-relaxometry parameters in the upper-arm nerves, primarily indicating demyelination. Peripheral nerve changes in ALS seem to be below the detection level of current state-of-the-art quantitative MR neurography.