Search Results (254)

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

Lower-limb rehabilitation exoskeletons must balance biomechanical compatibility, structural safety, and low mass to enable practical, repeatable gait assistance. This paper proposes a planar pantograph-derived exoskeleton leg driven by a Chebyshev Lambda linkage and develops an integrated workflow from mechanism synthesis to manufacturable optimization and experimental verification. A mannequin-coupled multibody model was built in MSC ADAMS to evaluate joint kinematics, end-point (foot) trajectories, and joint reaction forces under multiple scenarios (fixed-frame, ramp, stair ascent, and inclined-plane walking). The extracted joint loads were transferred to a parametric finite element model in ANSYS Workbench 2019, where response surface surrogates and a multi-objective genetic algorithm (MOGA) were used to minimize mass under stiffness and strength constraints. For the optimized load-bearing link, the selected minimum-mass design reached a component mass of 0.542 kg while respecting the imposed structural limits, i.e., a maximum total deformation below 0.2 mm and a maximum equivalent (von Mises) stress below 50 MPa (e.g., ~0.188 mm deformation and ~39 MPa stress in the optimal candidate). A rapid prototype was manufactured by 3D printing and experimentally evaluated using CONTEMPLAS high-speed video tracking, providing measured X_M(t) and Y_M(t) trajectories and joint-angle histories for quantitative comparison with simulations via RMSE metrics. Full article

Space-deployable antennas have development requirements of an ultra-large aperture, high stiffness, and multi-frequency multiplexing. To address the challenge of stiffness characterization in the multi-closed-loop complex systems of deployable mechanisms, this paper proposes a parametric stiffness modeling method and a static stiffness model is established, ranging from components and limbs to the overall mechanism. The motion/force mapping model of the deployable mechanism is obtained using screw theory, and the stiffness mapping from joint space to workspace is achieved via the Jacobian matrix. A comprehensive stiffness model of the deployable mechanism incorporating joint effects is established based on the principle of virtual work and the superposition principle of deformations, and its validity is verified through finite element simulation. Building on this, stiffness characteristics based on structural configuration are investigated, and structural forms with excellent stiffness performance are selected through comprehensive evaluation. Six configurations of the deployable mechanism are derived topologically from this structure, and the optimal configuration is selected based on stiffness performance. The parametric stiffness modeling method proposed in this study can effectively characterize the contribution of each component to the overall system stiffness. It lays a theoretical foundation for establishing a quantitative relationship between stiffness performance and configuration, enabling performance-based configuration optimization and dimensional optimization. Full article

Charcot neuro-osteoarthropathy remains one of the most serious complications of diabetic neuropathy, with the potential for rapid progression to deformity, ulceration and limb-threatening outcomes. The earliest signs and symptoms are often subtle and easily missed, yet early recognition provides a narrow window of opportunity to prevent irreversible structural change. Contemporary diagnostic pathways are underpinned by close clinical observation and correlation of bedside findings with detailed imaging analysis, enabling earlier identification of active disease before collapse occurs. This article provides a comprehensive overview of the Charcot foot, integrating clinical presentation, differential diagnosis and current approaches to investigation and management. It also highlights the challenges of monitoring disease activity over time, including remission and relapse, and the importance of timely specialist referral and multidisciplinary management. By reinforcing structured assessment and targeted intervention, this review aims to support consistent, evidence-informed care for people affected by Charcot neuro-osteoarthropathy. Full article

Background: Marinesco–Sjögren syndrome (MSS, MIM #248800) is a condition that is characterized by biallelic pathogenic variants in the SIL1 gene. Manifestations include congenital cataracts, cerebellar ataxia, progressive muscle weakness and skeletal deformities, delay in psychomotor development, hypergonadotropic hypogonadism and short stature. Muscular involvement has been extensively discussed as a clinical finding but there is little literature on muscle imaging. The aim of this paper is to systematically review muscular imaging techniques in MSS reported in the literature, and to describe the clinical and imaging features of two pediatric subjects with MSS. Methods: Having searched through three electronic databases (PubMed, Scopus and Web of Science) two articles, written in English, describing twelve patients with MSS mutations on whom muscle MRI imaging was performed, were selected. In addition, two paediatric cases (brother and sister) with Marinesco–Sjögren syndrome (MSS) and MRI muscle findings were added. Data on type of study, cohort characteristics, type of mutation, neuromuscular signs and symptoms, imaging assessment, electrophysiological findings, biopsies, CNS symptoms, ocular signs and muscle imaging data were collected and stored in a table. Results: Of the 239 articles examined, only 3 used a muscle imaging technique to describe myopathy in MSS; one used a CT while another a muscle MRI. All 14 patients showed signs of fatty replacement. The infiltration mainly affected the lower limbs, but involvement in the upper limb was described in some adult patients. Conclusions: Performing a muscle MRI in MSS can lead to the early identification of muscle involvement and may be a useful biomarker to monitor disease progression. Full article

Objectives: Medial open-wedge high tibial osteotomy (MOWHTO) is a surgical procedure used to treat medial compartment osteoarthritis of the knee with varus deformity. The aim of this study was to examine whether a larger correction angle in medial open wedge high tibial osteotomy (MOWHTO) leads to greater changes in postoperative patellar height (PH) and posterior tibial slope (PTS). Methods: Data from 83 patients who underwent MOWHTO were retrospectively analyzed. Lower limb alignment was evaluated using the hip–knee–ankle angle (HKAA). The PH was assessed using the Insall–Salvati index (ISI), the Blackburne–Peel index (BPI), the Caton–Deschamps index (CDI), the modified Miura–Kawamura index (MKI), and the plateau–patella angle (PPA). The PTS was determined using the Moore–Harvey method. Results: The median correction of HKAA was 8°. A decrease in PH was observed in the majority of cases across all methods, with the highest frequency of postoperative patella infera detected using the MKI. PTS most frequently increased, with a median increase of 3°. A significant association between the magnitude of HKAA correction and patellar height in the overall cohort was observed only for the MKI, whereas in patients with an HKAA correction ≥ 10°, significant associations were found for both the MKI and CDI. No significant association was found between the magnitude of HKAA correction and changes in posterior tibial slope in the overall cohort, while a significant negative correlation was observed in patients with an HKAA correction ≥ 10°. Conclusions: Assessment using the MKI demonstrated greater sensitivity in detecting postoperative PH decrease, particularly in identifying patella infera. The magnitude of HKAA correction was significantly associated with greater changes in PTS and PH in patients with a coronal plane correction of ≥10°. Full article

Exploring the lunar complex and extreme terrain presents formidable challenges for conventional lunar rovers. To address these limitations, this study proposes a novel hexapod jumping hybrid robot that incorporates a “figure-of-eight” (butterfly-shaped) six-branched wheel-legged mechanism and a jumping system that stores elastic energy via deformation of its elastic body. Inspired by the multimodal locomotion of grasshoppers, the robot dynamically switches between two operational modes: high-efficiency wheeled locomotion on relatively flat surfaces and agile jumping to traverse steep slopes and surmount large obstacles. A bio-inspired gait, inspired by the crawling patterns of a hexapod insect, is implemented using a Central Pattern Generator (CPG)-based controller to produce coordinated, rhythmic limb movements. Dynamic simulations of the jumping mechanism were conducted to optimize the critical parameters of the elastic structure and its associated control strategy. Experiments on a physical prototype were conducted to validate the robot’s wheeled mobility and jumping performance. The results demonstrate that the robot exhibits excellent adaptability to rugged terrains and obstacle-dense environments. The integration of multimodal locomotion and adaptive gait control significantly enhances the robot’s operational robustness and survivability in the harsh lunar environment, opening new possibilities for future lunar exploration missions. Full article

Objectives: This study aimed to evaluate longitudinal changes in knee muscle strength following open wedge high tibial osteotomy (OWHTO) for medial compartment knee osteoarthritis with varus deformity, with particular emphasis on differences between the operated and non-operated knees. Methods: This retrospective study included 78 patients who underwent OWHTO. All patients followed a standardized rehabilitation protocol consisting of protected weight-bearing for six weeks, followed by closed kinetic chain exercises and subsequent open kinetic chain exercises from three months postoperatively. Isokinetic knee extension and flexion strength were assessed preoperatively and at 3, 6, and 12 months postoperatively using a Biodex System IV dynamometer at angular velocities of 60°/s and 180°/s. Absolute muscle strength values and inter-limb strength deficits were analyzed. Statistical analyses were performed using the Shapiro–Wilk, Friedman, and Wilcoxon signed-rank tests, with significance set at p ≤ 0.05. Results: At 60°/s, knee extensor and flexor strength deficits significantly increased after surgery, peaking at three months postoperatively, and gradually improved; however, deficits remained significantly greater than preoperative values at one year (p < 0.05). Similar trends were observed at 180°/s, although they did not reach statistical significance. These deficits were primarily attributable to reduced muscle strength in the operated knee, while strength in the non-operated knee remained unchanged throughout follow-up. Conclusions: Knee muscle strength in the operated limb markedly declined during the first three months following OWHTO, particularly in maximal power, and generally required more than six months to recover toward preoperative levels. These findings emphasize the importance of targeted postoperative rehabilitation strategies focusing on early muscle power recovery after OWHTO. Full article

Background: The PITX1 gene encodes a transcription factor that plays a crucial role in the development of the lower limbs, pelvis, and structures derived from the first branchial arch. Pathogenic variants in PITX1 are associated with a limited spectrum of rare disorders, including congenital talipes equinovarus with or without long bone anomalies and/or mirror-image polydactyly, and Liebenberg syndrome. In 2020, a novel clinical phenotype, Mandibular–Pelvic–Patellar (MPP) syndrome, resulting PITX1 missense variants, was proposed. Case presentation: We report the fourth documented case of MPP syndrome worldwide, identified in a 17-year-old female patient presenting with congenital lower limb deformities, patellar aplasia, and micrognathia. Whole-genome sequencing revealed a heterozygous PITX1 missense variant NM_002653.5: c.412A>C, p.(Lys138Gln). The clinical phenotype included knee flexion contractures and severe equinovarus and planovalgus foot deformities requiring multiple staged reconstructive surgical procedures. Conclusions: This case supports recognition of MPP syndrome as a clinically and genetically distinct PITX1-related disorder. Our findings expand the phenotypic spectrum of MPP syndrome and suggest that severe congenital foot deformities represent a consistent and clinically relevant feature of this condition. Full article

Background: Congenital split foot/hand is a rare limb anomaly. Although various surgical techniques have been described, detailed gross anatomical studies of soft tissue adaptation, particularly in the foot, are extremely rare. This study presents a detailed anatomical description of a case of severe bilateral split foot. Methods: A comprehensive dissection was performed on the lower limb of a 64-year-old male donor with bilateral split foot/hand. Results: Radiographic evaluation classified the deformity as Blauth type IV, characterized by the absence of the lateral cuneiform bone and severe hypoplasia/aplasia of the second and third metatarsals. Significant changes were revealed in the musculotendinous apparatus. The key finding was a unique tendon loop passing through the central cleft, formed by the tendon of the extensor digitorum longus and connecting with the tendons of the flexor digitorum longus and flexor hallucis longus. Conclusions: This study presents the first detailed macroscopic anatomical description of split foot, demonstrating that this congenital anomaly involves complex, structured tendon and muscle adaptations that extend beyond skeletal deficiencies alone. The discovery of a persistent tendon loop—previously reported only once in split hand—indicates asynchronous development of skeletal and soft tissue structures. These findings should be taken into account for surgical planning, emphasizing the need to identify and manage such abnormal soft tissue structures during reconstructive procedures. Full article

Background and Objectives: Coronal plane deformities of the knee, particularly genu valgum and varum, represent common indications for guided growth in pediatric orthopedics. This study evaluates the clinical and radiographic outcomes of temporary hemiepiphysiodesis using tension-band plates in skeletally immature patients and identifies factors associated with successful correction. Materials and Methods: A retrospective review was conducted on patients treated with tension-band plate hemiepiphysiodesis for knee valgus or varus deformities between 2012 and 2023. Inclusion required open physes, pre- and postoperative full-length radiographs, and follow-up until implant removal or skeletal maturity. Mechanical axis parameters (mLDFA, mMPTA) were compared pre- and postoperatively, and correction rates were calculated. Idiopathic cases were analyzed separately from those with neurological or osteological disorders. Results: Sixty-six limbs were included (51 valgus, 15 varus). In the idiopathic subgroup, significant correction was achieved, with mLDFA improving by +5.19° and mMPTA by −1.88°, corresponding to annual correction rates of 4.75°/year and −1.74°/year, respectively (p < 0.001). Regression analysis showed no significant predictive value of age or treatment duration for total correction. Patients with pathological physes demonstrated inconsistent outcomes, often requiring additional procedures. No major complications occurred. Conclusions: Temporary hemiepiphysiodesis using tension-band plates is a safe, minimally invasive, and highly effective method for correcting idiopathic valgus deformities in growing children, with correction rates comparable to the existing literature. Outcomes in patients with neurological or osteological comorbidities remain less predictable, underscoring the need for individualized planning and close follow-up. Full article

Working equids are at high risk of musculoskeletal disorders due to strenuous labor, repetitive tasks, and harsh environmental conditions. This retrospective study describes the distribution of radiographically detected musculoskeletal findings in working equids presented to four Society for the Protection of Animals Abroad (SPANA) centers in Morocco, based on 498 animals and 1125 radiographs collected between 2015 and 2022. The study population was mainly composed of horses (78.1%), followed by donkeys (15.3%) and mules (6.6%). Most were males (65.7%), and the majority were between 5 and 15 years old (60.4%). The distal limb (foot, pastern, and fetlock) was the most frequently examined region (62.7%). Among the animals reviewed, 381 (76.5%) exhibited at least one radiographically detected abnormality, while 117 (23.5%) showed no visible osseous change. The most frequent findings included foot-related changes (36.2%), defined as non-fracture podiatric abnormalities, fractures (29.7%), and periosteal new bone formation (22%). Less frequent findings were degenerative joint disease (8.1%), joint subluxation or luxation (1.6%), epiphyseal abnormalities (1.6%), and angular deformities (0.8%). These results provide an overview of radiographically detected osseous changes in working equids under field conditions. They highlight the diagnostic value of radiography in low-resource environments and provide a basis for future field-based studies. Full article

Background/Objectives: Habitual patellar dislocation is a rare but debilitating form of patellofemoral instability in children and adolescents, frequently associated with underlying anatomical abnormalities and ligamentous laxity. Despite multiple surgical techniques, recurrence and suboptimal functional recovery remain concerns. This study aimed to identify the demographic, clinical, and imaging factors associated with postoperative recurrence and poorer functional outcomes in pediatric patients surgically treated for habitual patellar dislocation. Methods: A retrospective cohort study was conducted on pediatric patients treated between 2016 and 2024 for habitual patellar dislocation. Inclusion criteria required age ≤ 18 years, a minimum 12-month follow-up, and complete imaging documentation. Clinical evaluation included the Beighton hyperlaxity score, lower-limb alignment, and Lysholm Knee Score. Imaging parameters assessed patellar height (Caton–Deschamps Index), trochlear dysplasia, patellar tilt, patellar subluxation, genu valgum, and tibial tubercle–trochlear groove (TT–TG) distance. Surgical treatment consisted of individualized combinations of soft-tissue realignment, quadriceps lengthening, Roux–Goldthwait procedures, and MPFL reconstruction. Statistical analyses evaluated predictors of recurrence and postoperative Lysholm score. Results: Thirty-four patients (45 knees; mean age 12 years; 73.5% female) were included. Preoperative Lysholm scores improved from a mean of 73 to 94 postoperatively (p < 0.0001). Recurrence occurred in 32.35% of patients and was significantly associated with generalized hyperlaxity (p = 0.0041), trochlear dysplasia (p = 0.045), and lateral patellar subluxation (p = 0.039). Suboptimal postoperative Lysholm scores (<85) were observed in 11.76% of patients, all with recurrence, and were significantly associated with genu valgum (p = 0.0011) and patella alta (p = 0.036). No significant associations were found for rotational deformities or femoral condyle hypoplasia. Conclusions: Habitual patellar dislocation in children is multifactorial, and the likelihood of recurrence increases with cumulative risk factors such as hyperlaxity, trochlear dysplasia, lateral subluxation, patella alta, and genu valgum. Comprehensive preoperative assessment is essential to guide combined, individualized surgical strategies that optimize stability and functional recovery. No single technique is universally curative; rather, tailored multimodal approaches yield the most favorable outcomes. Full article

Background: Tibial pilon fractures are, in most cases, complex injuries caused by high-energy trauma. This type of fracture requires surgical stabilization and immobilization that impairs ankle function by reducing range of motion, muscle strength, and affecting the mechanical properties of the muscles. Methods: We evaluated 22 patients who required surgery for tibial pilon fractures and 22 age-matched healthy controls. Dynamometry assessed the isometric strength of the dorsiflexors and plantar flexors. Myotonometry of the tibialis anterior, peroneus longus, and medial and lateral gastrocnemius muscles analyzed the muscle tone, biomechanical (stiffness and decrement), and viscoelastic properties (mechanical stress relaxation and ratio of relaxation time to deformation time (creep). Results: Compared to the control group, the patients had significantly decreased isometric strength in both the dorsal flexors and plantar flexors on the affected side. Myotonometric measurements did not reveal significant differences in the tibialis anterior and peroneus longus muscles. Both medial and lateral gastrocnemius muscles exhibited significantly increased frequency and stiffness, and significantly decreased relaxation and creep in patients when compared to the control group. Conclusions: When compared to healthy controls, patients with surgically treated unilateral pilon fracture had a decreased isometric muscle force of ankle dorsiflexors and plantar flexors of both affected and non-affected lower limbs. Myotonometry indicated increased frequency and stiffness, along with decreased values of viscoelastic parameters (stress relaxation time and creep) in the medial and lateral gastrocnemius muscles on both sides. Full article