Search Results (124)

Ankle dorsiflexion range of motion (ADF-ROM) deficits has been linked to impaired function, altered gait, and injury risk. This study’s objective was to examine the acute effects of static self-stretching (SSS), foam rolling (FR), and instrument-assisted soft tissue mobilization (IASTM) of the posterior lower-leg on ADF-ROM and functional ankle outcomes in individuals with ADF-ROM deficits. Thirteen healthy, physically active college students with active ADF-ROM ≤ 13°, assessed in a non-weight-bearing position, completed all three interventions in a randomized, within-subject repeated-measures design. Pre- and post-intervention assessments included ADF-ROM, ankle plantar flexor isometric strength (APF-IS), single-leg countermovement vertical jump (SLCVJ), anterior reach distance in the Y-Balance Test (A-YBT), and gait parameters (contact time and plantar pressure). A two-way repeated-measures ANOVA with Bonferroni post hoc tests was used. Effect sizes reported as partial eta squared (${\eta }_p^2$) and Cohen $d_{\mathrm{z}}$. All interventions significantly improved ADF-ROM (p < 0.001; ${\eta }_p^2$ = 0.885), with IASTM showing the largest increase (50.7%, $d_{\mathrm{z}}$= 2.15), followed by FR (35.4%, $d_{\mathrm{z}}$ = 2.20) and SSS (21.5%, $d_{\mathrm{z}}$ = 1.82). Differences between IASTM and FR (p > 0.05, $d_{\mathrm{z}}$ = 0.40) and between FR and SSS (p > 0.05, $d_{\mathrm{z}}$ = 0.69) were nonsignificant, while IASTM was significantly greater than SSS (p < 0.05, $d_{\mathrm{z}}$ = 0.92). Significant gains were also seen in A-YBT (p < 0.05; ${\eta }_p^2$ = 0.302) and rearfoot plantar pressure (p < 0.01; ${\eta }_p^2$ = 0.482), although pairwise comparisons were nonsignificant and demonstrated small-to-moderate effect sizes ($d_{\mathrm{z}}$ = 0.35–0.52). No significant changes occurred in APF-IS, SLCVJ, or contact time and mid- and forefoot plantar pressures during roll-off. In conclusion, all interventions improved ADF-ROM, with IASTM and FR being comparably effective. However, only slight improvements in dynamic balance and certain gait parameters were noted, with no effect on strength or power. Full article

Compliant mechanisms have contributed to many advances in soft robotics, and there is strong motivation to translate these ideas to assistive devices where adaptive motion at the human interface is required. This work presents novel reconfigurable compliant joints (RCJs) as a parameterized joint element for functional biomimicry in lower-extremity joints for prosthetic knees and ankle–foot orthoses, with concepts that extend to other limb joints. The RCJ uses a rigid hub and outer ring joined by an array of flexible links with centerlines defined by cubic Bézier curves. Link shapes are organized into four Bézier classes (A–D), with base types using 10, 12, or 14 uniformly distributed link slots and variants generated by modifying active-link count and distribution, forming a structured morphology space of 12 configurations for machine design. Dual-extrusion 3D-printed prototypes are characterized by a custom testing apparatus using a 2.2 kN load cell at 25 mm/s over a 0–90° rotation range across six recorded load cycles to measure torque–angle curves and stiffness under large deformations. Angle-dependent stiffness is evaluated over three fixed intervals (0–30°, 30–60°, and 60–90°) to quantify multi-stage behavior. A 2-dimensional corotational frame model and a Simscape Multibody model, including a rolling-contact knee configuration, use the same parameterization to relate geometry, nonlinear mechanics, and system-level motion. Experiments and simulations show multi-stage torque–angle profiles and predictable stiffness modulation across all configurations, with both magnitude and transition angle tunable through Bézier class and active-link distribution, positioning the RCJ as a CAD/CAE-compatible joint architecture for assistive devices or wearable robotic systems and a basis for advancing functional biomimicry in compliant mechanism design. Full article

Background: Physical functional capacity plays a critical role in sports performance and changes markedly from adolescence to adulthood. This study aimed to compare the physical functional characteristics between adolescent and collegiate soccer athletes. Methods: Fifty elite male soccer athletes (30 adolescents, 20 college students) were assessed for joint range of motion, muscle flexibility, dynamic balance, and trunk functional capacity. Results: Adolescent athletes achieved significantly greater general joint laxity score than collegiate athletes (p = 0.01), with significantly greater hip range of motion across all planes (abduction, internal rotation, and external rotation; all p < 0.01). College athletes had significantly lower SLR degree (left: p < 0.01, right: p < 0.05) but significantly greater degrees on passive Ely’s test (p < 0.01) than adolescent athletes. Collegiate athletes delivered significantly superior dynamic balance performance in the Y-balance test, particularly in the posterolateral and posteromedial directions (all p < 0.05). Unexpectedly, trunk functional capacity was significantly lower in collegiate athletes compared with adolescents (p < 0.01). Limb asymmetry was observed in both groups: collegiate athletes showed asymmetry only in the anterior reach direction of the Y-balance test (p = 0.018), whereas adolescents exhibited asymmetry across multiple joints (ankle, hip, hamstrings, and quadriceps; all p < 0.05) and in the posterolateral direction of the Y-balance test (p < 0.01). Conclusions: Adolescent athletes demonstrated significantly superior joint range of motion and lower limb flexibility, whereas collegiate players exhibited better balance performance, indicating distinct functional profiles between the two cohorts, which may be associated with differences in training experience and developmental stages. Full article

Cerebral palsy (CP) often causes mobility limitations that require assistive devices such as Ankle Foot Orthoses (AFOs) to enhance functional stability. This study aims to develop an optimized 3D-printed AFO design that improves comfort, structural durability, and production efficiency for children with CP. The research applies a Design of Experiment approach using the Taguchi method to optimize 3D printing parameters, supported by tensile testing to identify the best material configuration. Design alternatives were prioritized using the Analytical Hierarchy Process, while Finite Element Analysis was conducted to evaluate mechanical performance under physiological loading. The selected PETG configuration (33% infill density and 0.15 mm layer thickness) demonstrated improved tensile strength and flexibility, contributing to enhanced structural behavior. A prototype was produced and validated using the Quebec User Evaluation of Satisfaction with Assistive Technology (QUEST) questionnaire. Results showed higher overall user satisfaction for the optimized 3D-printed AFO compared to conventional devices, particularly in safety, comfort, and durability. The integration of optimized material parameters, systematic design evaluation, and user-centered assessment provides an effective pathway toward improving AFO performance and supporting the mobility and quality of life of children with cerebral palsy. Full article

Background/Objectives: Juvenile hallux valgus (JHV) and flexible flatfoot (FFF) often coexist in children, yet their combined surgical management remains poorly explored. This study evaluates clinical and radiographic outcomes following a simultaneous approach using lateral hemiepiphysiodesis of the first metatarsal (LHFM) and calcaneal-stop (C-Stop) procedures in skeletally immature patients. Methods: A retrospective cohort of 24 bilateral patients (48 feet) aged 10–12 underwent LHFM and C-Stop between 2017 and 2023. Radiographic evaluation included Hallux Valgus Angle (HVA), Intermetatarsal Angle (IMA), Meary’s angle (MA), and transverse TaloCalcaneal (Kite’s) Angle (tTCA). The Foot and Ankle Disability Index (FADI) and the Tegner Activity Scale (TAS) were administered at the most recent follow-up and complications were recorded. Results: The mean follow-up was 3.7 years. Postoperative radiographs showed significant improvements in all parameters, with correction inversely correlated to baseline deformity severity. Full normalization of flatfoot parameters was achieved in 68.8% of feet, with mild residual deformity in the remainder. Males showed greater radiographic correction than females. IMA and HVA improved in most cases, reaching full normalization in 53.1% and 50% of feet, respectively. Clinically, all patients showed corrected hindfoot alignment and medial arch restoration; 90% achieved the maximum FADI score and 88% resumed recreational sports. Two cases of screw migration occurred, with one revision; no further complications were reported. Conclusions: Simultaneous correction of FFF and JHV using C-Stop and LHFM proved effective, yielding significant radiographic improvements and excellent functional outcomes in most cases, with minimal complications. However, full hallux alignment was achieved in only half of the cases, suggesting that additional distal metatarsal procedures may be needed for more severe deformities. Full article

Background: Arthroereisis is a well-accepted and relatively easy procedure to treat the flexible flatfeet in children and adolescents. A mild calf-muscle shortening is not seldom an accompanying feature. The need for a gastrocnemius recession in addition to arthroereisis is controversial. Therefore, the objective of this study is to investigate the need for a gastrocnemius recession in mild cases of gastrocnemius shortening to improve ankle dorsiflexion in addition to arthroereisis. Methods: Twenty-seven patients (ages 9–15 years) who underwent arthroereisis for painful idiopathic flatfeet were included in this non-randomised retrospective study, approved by Friedrich-Alexander University, Erlangen-Nürnberg (22-86-Br). The gait data of 18 typically developed children in same age group was used as reference. Based on the intraoperative Silfverskjöld test, two groups could be identified in the collective, one with shortened of gastrocnemius who underwent gastrocnemius recession (FFGR) and one without (FF). A control group included 18 feet of 18 typically developing children. Outcomes were evaluated by comparing pre- and postoperative clinical assessments including pain scores, gait analysis using a multi-segmental foot model, and radiological imaging. The mean follow-up was 22.1 months, and statistical analysis included a two-factor ANOVA. Results: No statistically significant differences in anthropometric, clinical, and gait parameters were observed between the groups preoperatively. Improvements in ankle dorsiflexion and pain were seen in both groups without statistical significance. There was no loss of calf-muscle strength or ankle power. Conclusions: Arthroereisis effectively corrects an idiopathic flexible flatfoot and reduces pain in children and adolescents. The gastrocnemius muscle stretches following arthroereisis and therefore, no lengthening is necessary when mildly shortened. The major limitations of this study are its retrospective nature, non-randomisation, and small size of the study collective. Full article

Background: Aging is associated with reduced joint flexibility and balance, which increases the risk of falls, especially during stair descent where motor control is critical. Stretching has been shown to improve ankle range of motion and gait speed. This study investigated the effects of a 4-week training program combining stretching plus resistance training (RT) with elastic bands on functional capacity and ankle stability during stair descent in older women. Methods: Twenty-four active older women (mean age: 73.1 ± 0.97 years) were randomly assigned to static stretching (SS), dynamic stretching (DS) and control (CG) groups. All participants completed two weekly 60 min sessions consisting of progressive RT preceded by three different warm-ups. The SS and DS groups completed static or dynamic stretching, while the CG walked. Assessments included 30s-Chair Stand (30s-CS), Handgrip Strength (HGS), Time Up and Go (TUG), Chair Sit and Reach (CSR), Rating of Perceived Exertion (RPE), and ankle kinematics during stair descent. Results: All groups improved 30s-CS and TUG (p < 0.05). Only the SS group improved CSR in both legs and the ankle dorsiflexion angle during stair descent at final foot contact (p = 0.002). RPE increased over time across all groups (p < 0.0001); however, the SS and DS groups reported lower exertion than the CG group in first–second weeks (p = 0.0001–0.003). Conclusions: SS prior to progressive RT improved flexibility and ankle kinematics during stair descent, thus reducing the perception of effort particularly during the initial training phase. These findings indicate the effectiveness of SS as a warm-up strategy for increasing ROM and potentially reducing the risk of falls in this population. Full article

Background: Idiopathic painful flexible flatfoot (FFF) in childhood can persist into adulthood, yet long-term data on subtalar arthroereisis via the calcaneo-stop (C-Stop) procedure are scarce. We aimed to evaluate clinical and functional outcomes at ≥10 years post-surgery and compare them with age-matched normative values in healthy populations. Methods: We conducted a single-time-point long-term follow-up on a subset of 232 children (age 10–14 years) selected from a retrospective cohort of 494 patients who underwent bilateral anterograde C-Stop between 2010 and 2014. Inclusion required idiopathic symptomatic FFF refractory to conservative care and a minimum 10-year follow-up. At a mean follow-up of 12.1 ± 2.5 years, patients completed the Foot and Ankle Ability Measure (FAAM) and Tegner Activity Scale (TAS). Secondary data included anthropometrics, implant details, accessory procedures, screw removal, and complications. Results: Respondents demonstrated excellent function: FAAM total 98.8 ± 3.7 (range 75–100) with 87.5% achieving the ceiling score; FAAM–ADL 99.3 ± 3.2; FAAM–Sport 98.0 ± 6.4. The mean TAS was 3.7 ± 2.0, with 53% active in sports—72% low-impact, 12% high-impact non-competitive, and 4% competitive. Sex and history of complications produced statistically significant but clinically small differences (<3% on FAAM total; <6 points on subscales). No outcome differences were observed by age or BMI, accessory procedures, or screw removal status. Conclusions: Ten years after C-Stop arthroereisis in childhood, patients exhibit functional scores comparable to normative values, high rates of ceiling effect on FAAM, and a modest level of physical activity predominantly in low-impact sports. Full article

Sport climbing has evolved into a demanding discipline where lower limb performance is increasingly relevant, particularly in indoor bouldering. This exploratory study aimed to identify trends in strength and flexibility variables of the lower limbs in 24 recreational climbers (17 males, seven females), classified by sex and climbing level. Male climbers showed significantly greater performance in all measures of strength and power, including vertical and horizontal jumps, pull-ups, and handgrip strength. In contrast, female climbers demonstrated superior lower-limb flexibility and hip mobility, with significant differences observed when normalized to height. They also showed slightly better ankle dorsiflexion, although this difference was not statistically significant. Climbing level (mean: 6c+) correlated significantly with pull-ups (r = 0.598, p = 0.002), relative grip strength (r = 0.440, p = 0.032), and fat mass (r = −0.415, p = 0.043). Despite the lack of association between lower-limb performance and climbing grade, unilateral tests such as the Hop Test and hip mobility assessments may hold value for injury prevention and movement control. These findings highlight that lower-limb training, particularly strength, unilateral control, and flexibility, should not be excluded from physical preparation in climbing. Preventive strategies focusing on joint stability are especially recommended for female climbers due to their higher joint laxity and increased ACL injury risk. Future research should incorporate climbing-specific assessments and explore these variables in other climber profiles, such as elite, youth, or injured athletes. Full article

Background/Objectives: The projected rise in limb amputations highlights the need for advancements in prosthetic technology. Current transtibial prosthetic designs primarily focus on sagittal plane kinematics but often neglect both the ankle kinematics and kinetics in the coronal plane, and the metatarsophalangeal joint, which play critical roles in gait stability and efficiency. This study aims to evaluate the combined effects of compliance in the coronal plane and a flexible toe joint on prosthetic gait using non-amputated participants as a model. Methods: We conducted gait trials on ten non-amputated individuals in the presence and absence of compliance in the coronal plane and toe compliance, using a previously developed three-degree-of-freedom (DOF) prosthetic foot with a prosthetic simulator. We recorded and analyzed sagittal and coronal kinematic data, ground reaction forces, and electromyographic signals from muscles involved in the control of gait. Results: The addition of compliance in the coronal plane and toe compliance had significant kinematic and muscular effects. Notably, this compliance combination reduced peak pelvis obliquity by 27%, preserved the swing stance/ratio, and decreased gluteus medius’ activation by 34% on the non-prosthetic side, compared to the laterally rigid version of the prosthesis without toe compliance. Conclusions: The results underscore the importance of integrating compliance in the coronal plane and toe compliance in prosthetic feet designs as they show potential in improving gait metrics related to mediolateral movements and balance, while also decreasing muscle activation. Still, these findings remain to be validated in people with transtibial amputations. Full article

Background/Objectives: Subtalar arthroereisis (STA) is a widely used surgical procedure for symptomatic pediatric flexible flatfoot. However, implant migration remains a concern due to its potential impact on long-term correction and complications. This study evaluated the migration pattern of STA implants and assessed long-term clinical and radiographic outcomes. Methods: This retrospective cohort study included 47 feet from children aged 8–13 years who underwent STA with adjunctive soft tissue procedures between 2014 and 2018, following ≥6 months of failed conservative treatment, with a minimum follow-up of 5 years. Exclusion criteria included neuromuscular or rigid flatfoot. Weight-bearing radiographs assessed anteroposterior (AP) and lateral Meary’s angles, reflecting forefoot-to-hindfoot alignment, and calcaneal pitch, indicative of longitudinal arch height. Implant migration was recorded and clinical outcomes were measured by the American Orthopedic Foot and Ankle Society (AOFAS) score. Measurements were recorded preoperatively, immediately postoperatively, and at 1 month, 3 months, 6 months, 1 year, and 5 years. Results: Radiographic correction was significant and sustained at 5 years. The AP Meary’s angle improved from 13.09° to 5.26° at 1 month and 6.69° at 5 years (p < 0.001); lateral Meary’s angle from 9.77° to 4.06° and 4.88° (p < 0.001); and calcaneal pitch from 14.52° to 16.87° and 16.89° (p < 0.001), respectively. AOFAS scores increased from 67.52 to 90.86 at 1 month and 96.33 at 5 years (p < 0.001). Implant migration peaked within the first postoperative month (mean: 3.2 mm on ankle AP view; 3.0 mm on foot AP view) and stabilized thereafter. Four cases of complications included implant dislodgement, subsidence, and persistent sinus tarsi tenderness, which were successfully resolved after appropriate management. No recurrence of deformity was observed. Conclusions: STA implant migration is most pronounced during the first month, likely due to physiological settling as the foot adapts to altered biomechanics. With appropriate implant selection, technique, and follow-up, migration does not compromise long-term correction or outcomes. In general, symptomatic cases can often be managed conservatively prior to implant removal. Full article

Nowadays, Fused Filament Fabrication (FFF) 3D printing offers promising opportunities for the customized manufacturing of ankle–foot orthoses (AFOs) targeted towards rehabilitation purposes. Polypropylene (PP) represents an ideal candidate in orthotic applications due to its light weight and superior mechanical properties, offering an excellent balance between flexibility, chemical resistance, biocompatibility, and long-term durability. However, Additive Manufacturing (AM) of AFOs based on PP remains a major challenge due to its limited bed adhesion and high shrinkage, especially for making large parts such as AFOs. The primary innovation of the present study lies in the optimization of FFF 3D printing parameters for the fabrication of functional, patient-specific orthoses using PP, a material still underutilized in the AM of medical devices. Firstly, a thorough thermomechanical characterization was conducted, allowing the implementation of a (thermo-)elastic material model for the used PP filament. Thereafter, a Taguchi design of experiments (DOE) was established to study the influence of several printing parameters (extrusion temperature, printing speed, layer thickness, infill density, infill pattern, and part orientation) on the mechanical properties of 3D-printed specimens. Three-point bending tests were conducted to evaluate the strength and stiffness of the samples, while additional tensile tests were performed on the 3D-printed orthoses using a home-made innovative device to validate the optimal configurations. The results showed that the maximum flexural modulus of 3D-printed specimens was achieved when the printing speed was around 50 mm/s. The most significant parameter for mechanical performance and reduction in printing time was shown to be infill density, contributing 73.2% to maximum stress and 75.2% to Interlaminar Shear Strength (ILSS). Finally, the applicability of the finite element method (FEM) to simulate the FFF process-induced deflections, part distortion (warpage), and residual stresses in 3D-printed orthoses was investigated using a numerical simulation tool (Digimat-AM^®). The combination of Taguchi DOE with Digimat-AM for polypropylene AFOs highlighted that the 90° orientation appeared to be the most suitable configuration, as it minimizes deformation and von Mises stress, ensuring improved quality and robustness of the printed orthoses. The findings from this study contribute by providing a reliable method for printing PP parts with improved mechanical performance, thereby opening new opportunities for its use in medical-grade additive manufacturing. Full article

This article presents a series of innovative systems developed through student laboratory projects, comprising two autonomous vehicles, a quadrupedal walking robot, an active ankle-foot orthosis, a ball-on-beam balancing mechanism, a ball-on-plate system, and a manipulator arm, all actuated by pneumatic artificial muscles (PAMs). Due to their flexibility, low weight, and compliance, fluidic muscles demonstrate substantial potential for integration into various mechatronic systems, robotic platforms, and manipulators. Their capacity to generate smooth and adaptive motion is particularly advantageous in applications requiring natural and human-like movements, such as rehabilitation technologies and assistive devices. Despite the inherent challenges associated with nonlinear behavior in PAM-actuated control systems, their biologically inspired design remains promising for a wide range of future applications. Potential domains include industrial automation, the automotive and aerospace sectors, as well as sports equipment, medical assistive devices, entertainment systems, and animatronics. The integration of self-constructed laboratory systems powered by PAMs into control systems education provides a comprehensive pedagogical framework that merges theoretical instruction with practical implementation. This methodology enhances the skillset of future engineers by deepening their understanding of core technical principles and equipping them to address emerging challenges in engineering practice. Full article

Athletic Tape is widely used as an immediate and cost-effective intervention for flexible flat feet, offering a practical alternative to orthotic devices and exercise therapies. This study aimed to compare the effects of low-dye and anti-pronation taping (elastic and inelastic) on ankle strength, gait parameters, and balance control in women with flexible flat feet. Thirty women were evaluated under four conditions: no taping, low-dye taping, elastic anti-pronation taping, and inelastic anti-pronation taping. Each condition was tested at 3-day intervals. Outcome measures included ankle muscle strength, step length, stride length, balance control ability assessed using the Romberg and limits of stability tests. Repeated-measures analysis of variance and post hoc least significant difference analyses were used to determine statistical significance. Additionally, effect sizes (η²) were calculated for the primary outcomes. Dorsiflexion strength significantly improved with elastic taping (p < 0.05). Step length increased with both elastic and inelastic taping, whereas stride length improved only with elastic taping. All taping methods significantly reduced the limits of stability compared with the no-taping condition (p < 0.05). Athletic Tape interventions, especially elastic anti-pronation taping, may reduce excessive foot pronation and improve ankle strength and gait performance in women with flexible flat feet. Full article

In this work, energy was harvested from ankle flexion during gait. For this, two piezoelectric thin films were tested: PVDF and CdS. The PVDF film was a commercial option, and the CdS film was fabricated in our laboratory. Deposition of the CdS film is also reported in this work. Energy harvested during gait from heel strike and ankle flexion was compared. Tests were performed with 10 healthy volunteers walking on a treadmill at 1.2–1.5 km/h. The volunteers wore a sock with piezoelectric films incorporated in the heel and ankle joint (talocrural joint). Tests were performed first with the PVDF film and then with the CdS film. The CdS thin film obtained a d₃₃ coefficient of 1.4928 nm/V, indicating high electrical energy generated from strain-stress. The talocrural joint generated the most energy: 11.359 μJ for the PVDF film and 0.854 μJ for the CdS film. Although the CdS film generated less energy than the commercial option, it was shown that harvesting energy from ankle flexion increased the energy harvested by more than 700% during gait compared to the energy harvested from heel-to-ground impact. Full article