Search Results (128)

Background/Objectives: This study focuses on the motion planning and control of an active ankle–foot orthosis (AFO) that leverages biomechanical insights to mitigate footdrop, a deficit that prevents safe toe clearance during walking. Methods: To adapt the motion of the device to the user’s walking speed, a geometric model was used, together with real-time measurement of the user’s gait cycle. A geometric speed-adaptive model also scales a trapezoidal ankle-velocity profile in real time using the detected gait cycle. The algorithm was tested at three different walking speeds, with a prototype of the AFO worn by a test subject. Results: At walking speeds of 0.44 and 0.61 m/s, reduced tibialis anterior (TA) muscle activity was confirmed by electromyography (EMG) signal measurement during the stance phase of assisted gait. When the AFO was in assistance mode after toe-off (initial and mid-swing phase), it provided an average of 48% of the estimated required power to make up for the deliberate inactivity of the TA muscle. Conclusions: Kinematic analysis of the motion capture data showed that sufficient foot clearance was achieved at all three speeds of the test. No adverse effects or discomfort were reported during the experiment. Future studies should examine the device in populations with footdrop and include a comprehensive evaluation of safety. Full article

Background/Objectives: There exists a need to capture the current landscape of the literature for lumbar decompression on muscle strength, as measured by manual muscle testing (MMT), in cohorts with foot drop secondary to lumbar degenerative disease (LDD). Methods: A literature search of PubMed, EMBASE, CINAHL, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, Scopus, and Web of Science was conducted from each database’s inception to 21 March 2025. Eligible studies reported patients with LDD-related foot drop treated surgically. This review was registered in PROSPERO (ID: CRD42024550980). Results: A total of 20 studies comprising 918 patients met the eligibility criteria, with most cases attributable to lumbar disc herniation (79% of patients, 95% CI: 0.72–0.85, I² = 96%) or spinal stenosis (22% of patients, 95% CI: 0.15–0.30, I² = 96%). Following surgery, 60% of patients (95% CI: 0.44–0.75, I² = 97%) achieved an MMT score of 4–5, indicating recovery, while 82% (95% CI: 0.76–0.88, I² = 89%) demonstrated an improvement of at least one MMT grade. No improvement was seen in 18% of patients (95% CI: 0.12–0.24, I² = 89%). For pain, the preoperative VAS mean was 5.91 (95% CI: 4.21–7.60, I² = 99%), while the postoperative mean was 1.00 (95% CI: −0.05–2.06, I² = 99%). Overall complications were reported at 1% (95% CI: −0.00–0.02, I² = 0%). Conclusions: Lumbar decompression achieves clinically meaningful recovery of LDD-induced foot drop. However, this meta-analysis highlights the overlooked portion of patients who will not respond, providing a sequential approach for future investigation of these cohorts through foundational evidence of the present literature base. Full article

Background/Objectives: In orthopedic (diabetic) foot surgery, the serum C-reactive protein (CRP) level is frequently measured not only as a diagnostic tool, but also as a control inflammatory marker in the follow-up of postoperative surgical-site infections (SSIs) Methods: We investigated the predictive value of the post-debridement routine (control) serum CRP level in adult (diabetic) patients with an SSI in the foot. We excluded community-acquired (diabetic foot) infections and focused on the predictive accuracy of routine (control) CRP measurements in terms of ultimate therapeutic failures. Results: The median pre- and postoperative CRP levels were 25 mg/L and 8.8 mg/L, respectively. In group comparisons and multivariate assessment, neither the immediate (relative and absolute) drop in the serum CRP level, nor its values between 5 and 8 weeks and between 11 and 14 weeks predicted the failure risk of 19%. In contrast, in cases of surprisingly elevated CRP levels, this finding leads to unnecessary radiological (median costs approximatively USD 200), clinical, microbiological urinary sample (median costs USD 50), and laboratory (one CRP sample USD 10) exams. These additional exams also likely prolong the duration of hospitalization by one to two days (e.g., whilst awaiting the microbiological results) and often generate unnecessary consultations among internist and/or infectious diseases experts (USD 50). Conclusions: Routine, postoperative CRP monitoring during the treatment of established orthopedic (diabetic) foot SSIs is unnecessarily costly, and should be avoided in favor of clinical surveillance of the postoperative evolution. Full article

This article contains a synthetic proof of the following proposition: consider a conic $c_1$ and its variable chord $AB$, which subtends a right angle at a given point P. Then, the foot E of the perpendicular dropped from P onto the line $AB$ lies on a certain circle (the line being the limiting case of the circle). To prove this proposition, we show how Poncelet’s closure theorem for quadrilaterals can be derived by elementary projective considerations only (without any computations, either in Cartesian or projective coordinates). Finally, the limiting case of the proposition, where the point P lies on the conic, is also mentioned. The problem can then be reduced to Frégier’s theorem and may represent a slightly different perspective on this theorem. Full article

As populations age, particularly in countries like Japan, mobility impairments related to ankle joint dysfunction, such as foot drop, instability, and reduced gait adaptability, have become a significant concern. Active ankle–foot orthoses (AAFO) offer targeted support during walking; however, most existing systems rely on rule-based or threshold-based control, which are often limited to sagittal plane movements and lacking adaptability to subject-specific gait variations. This study proposes an approach driven by neuromuscular activation using surface electromyography (EMG) and a Gated Recurrent Unit (GRU)-based deep learning model to predict plantar pressure distributions at the heel, midfoot, and toe regions during gait. EMG signals were collected from four key ankle muscles, and plantar pressures were recorded using a customized sandal-integrated force-sensitive resistor (FSR) system. The data underwent comprehensive preprocessing and segmentation using a sliding window method. Root mean square (RMS) values were extracted as the primary input feature due to their consistent performance in capturing muscle activation intensity. The GRU model successfully generalized across subjects, enabling the accurate real-time inference of critical gait events such as heel strike, mid-stance, and toe off. This biomechanical evaluation demonstrated strong signal compatibility, while also identifying individual variations in electromechanical delay (EMD). The proposed predictive framework offers a scalable and interpretable approach to improving real-time AAFO control by synchronizing assistance with user-specific gait dynamics. Full article

Tunnel lining structures, which are subjected to the combined effects of water and soil pressure as well as a water-rich erosion environment, undergo a corrosion-induced damage and degradation process in the reinforced concrete, gradually leading to structural failure and a significant decline in service performance. By introducing the Cohesive Zone Model (CZM) and the concrete damage plastic model (CDP), a three-dimensional numerical model of the tunnel lining structure in mining method tunnels was established. This model takes into account the multiple effects caused by steel reinforcement corrosion, including the degradation of the reinforcement’s performance, the loss of an effective concrete cross section, and the deterioration of the bond between the steel reinforcement and the concrete. Through this model, the deformation, internal forces, damage evolution, and degradation characteristics of the structure under the effects of the surrounding rock water–soil pressure and steel reinforcement corrosion are identified. The simulation results reveal the following: (1) Corrosion leads to a reduction in the stiffness of the lining structure, exacerbating its deformation. For example, under high water pressure conditions, the displacement at the vault of the lining before and after corrosion is 4.31 mm and 7.14 mm, respectively, with an additional displacement increase of 65.7% due to corrosion. (2) The reinforced concrete lining structure, which is affected by the surrounding rock loads and expansion due to steel reinforcement corrosion, experiences progressive degradation, resulting in a redistribution of internal forces within the structure. The overall axial force in the lining slightly increases, while the bending moment at the vault, spandrel, and invert decreases and the bending moment at the hance and arch foot increases. (3) The damage range of the tunnel lining structure continuously increases as corrosion progresses, with significant differences between the surrounding rock side and the free face side. Among the various parts of the lining, the vault exhibits the greatest damage depth and the widest cracks. (4) Water pressure significantly impacts the internal forces and crack width of the lining structure. As the water level drops, both the bending moment and the axial force diminish, while the damage range and crack width increase, with crack width increasing by 15.1% under low water pressure conditions. Full article

Background and Objectives: The anterior cruciate ligament (ACL) is crucial for knee stability, preventing anterior displacement of the tibia and rotation relative to the femur. Despite ACL reconstruction (ACLR), residual instability is common, affecting knee function. Anterolateral ligament reconstruction (ALLR) alongside ACLR improves outcomes, as the ALL plays a significant role in rotational stability. This study aims to assess the clinical and functional outcomes of the ACLR+ALLR combination using biomechanical testing in patients with at least ten months of follow-up. Materials and Methods: This cross-sectional comparative cohort study involves patients with ACLR. Inclusion criteria were adult patients who underwent ACLR within the last 3 years, with the same surgical technique performed by a single operator. Patients underwent anamnestic and clinical evaluation and completed Lysholm and KOOS questionnaires. Biomechanical tests included a Unilateral Drop Jump, a Countermovement Jump with knee rotation, and a five-repetition Sit-To-Stand. Force platforms, a camera, and surface electromyography were used to assess biomechanical stability and joint function. Results: This study included 18 subjects, 5 with ACLR and ALLR, and 13 with ACLR alone. The groups showed no significant differences in the KOOS and Lysholm scales and clinical outcomes. Muscle trophism reduction compared to the contralateral limb was noted in both groups. Biomechanical evaluations showed no difference in Quadriceps muscle activity during the landing phase of the Drop Jump. However, the ACL-ALL group exhibited fewer spikes and fewer knee joint angular excursions during ground impact stabilization. In the 5-STS task, a significant difference was observed in the vertical force peak. Differences in muscle activity during foot rotation and force components during the jumping phase were noted in the Countermovement Jump. Conclusions: ACLR combined with ALLR shows similar perceived joint function but improved biomechanical joint stability. Further studies with larger samples and longer follow-ups are needed for validation. Full article

Snowdrift, as a natural disaster, constantly compromises railway traffic by affecting how snow accumulates on the subgrade. This paper establishes a unified set of similarity criteria for wind tunnel testing, using viscous silica sand to simulate snow particles. By employing a geometric scale model (1:30) and similarity criteria (size, motion, dynamics, accumulation patterns, and time scales), it systematically investigates the evolution patterns of wind-induced snow accumulation on two types of roadbed structures: embankments and excavations. This study also evaluates the effectiveness of snow fences, proposing optimized placement distances and quantifying the effects of snow accumulation platform width. The results showed the following: (1) Snow on embankments has a “U”-shaped distribution, with the lowest wind speed (<0.5 m/s) and maximum accumulation at the leeward slope’s foot. In excavations, snow forms an “M”-shaped distribution, with significantly reduced wind speeds (<1 m/s) on the accumulation platform. (2) Snow fences effectively manage snow placement by lowering wind speed (below 1 m/s). A single-row snow fence with a porosity of 50% and a height of 3 m performs best when placed at seven times its height (7 H) from the slope’s toe. (3) A 5 m snow accumulation platform in excavations reduces surface snow accumulation (distribution coefficient drops to 1.6), outperforming scenarios without a platform (coefficient of 2.0). These findings contribute to the prevention and control of snowdrift disasters along railway lines in cold regions. They offer practical guidance for optimizing snow fence configurations, while also laying a foundation for future improvements in experimental accuracy through advanced techniques such as PIV and real-snow testing. Full article

Common peroneal nerve neuropathy at the fibular head secondary to weight loss is known as slimmer’s paralysis. Although this pathology has long been documented in medical literature, it has gained more clinical significance in recent years due to the global rise in obesity and the increasing pursuit of rapid weight loss methods. While case reports exist in the current literature, there are limited data regarding its optimal management. This study summarizes all reported cases of common peroneal nerve paralysis after weight loss and reports one additional case, exploring disease mechanisms as well as diagnostic and therapeutic strategies. A literature review was conducted on the platforms PubMed, Google Scholar, and EMBASE. A total of 380 patients were included. Laterality of neuropathy was specified in 297 (78.16%) patients: 285 (95.96%) with unilateral neuropathy and 12 (4.04%) with bilateral neuropathy. A total of 19 (5.00%) patients had sudden onset, and in 145 (38.16%) of cases, the Tinel’s sign was positive. Additionally, 373 (98.16%) patients underwent nerve conduction studies, demonstrating the fibular head as the site of injury. MRI or ultrasound imaging of the knee is indicated to exclude compressive etiology. A total of 302 (79.47%) cases were treated surgically and 42 (11.58%) conservatively, predominantly with favorable outcomes, regardless of the therapeutic approach chosen. Although the predominance of surgically treated cases in the literature limits definitive treatment recommendations, conservative management appears appropriate when an extended recovery time is acceptable, while surgical decompression is indicated in cases showing no improvement after 3 months. Full article

Passive Dynamic Ankle–Foot Orthoses (PD-AFOs) are medical devices prescribed to individuals with foot drop, a condition characterized by weakness of the ankle dorsiflexor muscles. PD-AFOs can store and release energy during the stance phase of the gait cycle, while supporting the foot in the swing phase. This study aimed at estimating the energetics of a novel fiberglass-reinforced polyamide custom PD-AFO in a population of mild foot drop patients. Eight PD-AFOs were designed and 3D-printed via selective laser sintering for eight participants with a unilateral foot drop condition. Lower limb kinematics and AFO flexion/extension were recorded during comfortable walking speed via skin marker-based stereophotogrammetry. The stiffness of each AFO was measured via an ad hoc experimental setup. The elastic work performed by the PD-AFO during gait was calculated as the dot product of the calf-shell resisting moment and the rotation angle. The average maximum energy stored by the calf-shell across all PD-AFOs was 0.013 ± 0.005 J/kg. According to this study, 3D-printed custom PD-AFOs made with fiberglass-reinforced polyamide can store some elastic energy, which is released to the ankle during push-off. Further studies should be conducted to assess the effect of this energy return mechanism in improving the gait of individuals with deficits of the ankle plantarflexor muscles. Full article

Post-stroke hemiplegia often leads to gait asymmetry, mobility reduction, and increased fall risk. Foot Drop Stimulation (FDS) is used in rehabilitation to improve dorsiflexion and gait patterns. Through cyclogram-based analysis, this retrospective study evaluated the effectiveness of FDS in enhancing inter-limb gait symmetry in 21 post-stroke hemiplegic individuals following 10 sessions of treadmill training combined with FDS. Participants underwent 3D gait analysis pre- and post-intervention, performed by means of optical motion capture system, from which spatiotemporal and cyclogram features of the hip, knee, and ankle were computed. FDS was found to significantly improve dynamic range of motion (ROM) of the affected side at hip (+5%) and knee (+9%) joints. Cyclogram analysis showed that FDS reduced inter-limb hip asymmetry (orientation: 13.35° to 10.65°, Trend Symmetry Index: 19.09° to 15.46°), though no improvements were observed at the ankle. FDS with treadmill training improved hip and knee symmetry, supporting cyclogram-based assessments for gait rehabilitation and highlighting the need for targeted ankle interventions. Further research is needed to explore long-term effects and optimize rehabilitation strategies. Full article

Background/Objectives: After spinal cord injury (SCI), poor dorsiflexor control and involuntary plantar-flexor contraction impair walking. As whole-body vibration (WBV) improves voluntary muscle activation and modulates reflex excitability, it may improve ankle control. In this study, the dosage effects of WBV on walking speed, dorsiflexion, and spinal reflex excitability were examined. Methods: Sixteen people with chronic motor-incomplete SCI participated in this randomized sham-control wash-in study. Two weeks of sham stimulation (wash-in phase) were followed by either 2 weeks of eight repetitions (short bout) or sixteen repetitions of WBV (long bout; intervention phase) per session. Walking speed, ankle angle at mid-swing, and low-frequency depression of the soleus H-reflex were measured before and after the wash-in phase and before and after the intervention phase. Results: A significant dosage effect of WBV was not observed on any of the measures of interest. There were no between-phase or within-phase differences in ankle angle during the swing phase or in low-frequency depression. When dosage groups were pooled together, there was a significant change in walking speed during the intervention phase (mean = 0.04 m/s, standard deviation = 0.06, p = 0.02). There was not a significant correlation between overall change in walking speed and dorsiflexion angle or low-frequency depression during the study. Conclusions: Whole-body vibration did not have a dosage-dependent effect on dorsiflexion during the swing phase or on spinal reflex excitability. Future studies assessing the role of corticospinal tract (CST) descending drive on increased dorsiflexor ability and walking speed are warranted. Full article

Background: Running-related injuries are often associated with biomechanical inefficiencies, particularly in the sagittal and frontal planes. This study evaluates the effects of three interventions—reduced heel-to-toe drop (HTD) shoes, increased cadence, and inversion foot orthoses—on key kinematic parameters: ankle dorsiflexion, knee flexion, and hip adduction (measured at foot strike and at their respective peak joint angles during the stance phase). Methods: Nineteen recreational runners (ten males and nine females; mean ± SD: age 26.4 ± 4.3 years; height 174.2 ± 7.8 cm; weight 68.3 ± 9.6 kg; BMI 22.5 ± 2.1 kg/m²) participated in a 3D motion capture study under five experimental conditions: baseline (10 mm HTD, no cadence adjustment, no foot orthoses), full intervention (5 mm HTD, +10% cadence, orthoses), and three partial interventions: HTD combined with orthoses, HTD combined with increased cadence, and cadence increase alone. Kinematic changes were analyzed for statistical significance. Results: The full intervention significantly increased ankle dorsiflexion at foot strike (from 8.11° to 10.44°; p = 0.005) and reduced peak knee flexion (from 45.43° to 43.07°; p = 0.003). Cadence adjustments consistently produced improvements, while orthoses and HTD alone showed effects on ankle flexion only. Conclusions: Combining structural (HTD and orthoses) and dynamic (cadence) modifications optimizes running biomechanics, providing evidence-based strategies for injury prevention and performance enhancement. Full article

Background: Running is a popular physical activity known for its health benefits but also for a high incidence of lower-limb injuries. This study examined the effects of three biomechanical interventions—cadence adjustments, footwear modifications, and foot orthoses—on plantar pressure distribution and spatiotemporal running parameters. Methods: A quasi-experimental, repeated-measures design was conducted with 23 healthy recreational runners (mean age 25, mean BMI 22.5) who ran at least twice per week. Five conditions were tested: baseline (C0), increased cadence (C1), orthoses (C2), low-drop footwear (C3), and a combination of these (C4). Data were collected on a Zebris treadmill, focusing on rearfoot contact time, peak forces, and stride length. Results: Increasing cadence (C1) reduced rearfoot impact forces (−81.36 N) and led to a shorter stride (−17 cm). Low-drop footwear (C3) decreased rearfoot contact time (−1.89 ms) and peak force (−72.13 N), while shifting pressure toward the midfoot. Orthoses (C2) effectively redistributed plantar pressures reducing rearfoot peak force (−41.31 N) without changing stride length. The combined intervention (C4) yielded the most pronounced reductions in peak forces across the rearfoot (−183.18 N) and forefoot (−139.09 N) and increased midfoot contact time (+5.07 ms). Conclusions: Increasing cadence and low-drop footwear significantly reduced impact forces, improving running efficiency. Orthoses effectively redistributed plantar pressures, supporting individualized injury prevention strategies. These findings suggest that combining cadence adjustments, footwear modifications, and orthoses could enhance injury prevention and running efficiency for recreational runners. Full article

Lower extremity misalignments increase the risk of chronic overload and acute injuries during sports and daily activities. Medial positioning of the knee and foot in the frontal plane is one of the key biomechanical risk factors associated with lower extremity injuries and pain. Different exercise interventions have been implemented to counteract misalignments. However, most studies have been conducted on clinical populations. Therefore, in this review, we aimed to assess the preventive effects of exercise interventions on frontal plane knee and foot posture in healthy individuals. Electronic databases (PubMed, Web of Science, PEDro) were systematically searched for original articles published between 2008 and 2024. This review included clinical trials on healthy adults (18–45 years) with or without lower extremity biomechanical misalignments, examining the effects of exercise interventions alone on knee and foot frontal plane biomechanics. Eligible studies reported at least one relevant frontal plane foot and knee biomechanical measure, such as knee valgus/abduction, medial knee displacement, foot pronation/eversion, or navicular drop. Studies involving non-exercise interventions, single-session protocols, and participants with neurological or spinal disorders, pain, or injury were excluded. A total of 35 articles with 1095 participants were included in this review. A total of 20 studies included individuals without a biomechanical misalignment, and 15 studies focused on individuals with a biomechanical misalignment. Mean values, standard deviations, and p-values were extracted from the included studies. Effect sizes and confidence intervals were then calculated to provide a quantitative presentation of the data. In conclusion, in healthy individuals without biomechanical misalignment, technique training and core muscles strengthening were most effective for improving knee valgus. Hip, core, and foot muscle strengthening reduced foot pronation in those with pronated feet, while short foot exercises improved foot positioning in individuals with flat feet. Combining lower extremity strengthening with knee position control training may reduce knee valgus in individuals with increased knee valgus. Full article