Search Results (45)

This paper presents a real-time framework for bilateral gait reconstruction and adaptive joint control using sparse inertial sensing. The system estimates full lower-limb motion from a single-side inertial measurement unit (IMU) by applying a pipeline that includes signal smoothing, temporal alignment via Dynamic Time Warping (DTW), and motion modeling using Gaussian Mixture Models with Regression (GMM-GMR). Contralateral leg trajectories are inferred using both ideal and adaptive symmetry-based models to capture inter-limb variations. The reconstructed motion serves as reference input for joint-level control. A classical Proportional–Integral–Derivative (PID) controller is first evaluated, demonstrating satisfactory results under simplified dynamics but notable performance loss when virtual stiffness and gravity compensation are introduced. To address this, an adaptive fuzzy PID controller is implemented, which dynamically adjusts control gains based on real-time tracking error through a fuzzy inference system. This approach enhances control stability and motion fidelity under varying conditions. The combined estimation and control framework enables accurate bilateral gait tracking and smooth joint control using minimal sensing, offering a practical solution for wearable robotic systems such as exoskeletons or smart prosthetics. Full article

Purpose: The purpose of this scoping review was to systematically identify and summarize the existing literature on non-spinal clinical applications of EOS imaging and identify related evidence gaps. Method: The study followed the PRISMA-ScR guidelines. A systematic literature search was conducted in Embase, MEDLINE, CINAHL, Scopus, Cochrane, Academic Search Premier, and OpenGrey databases in November 2022 and updated in December 2023. Original research from 2003 to 2023 was eligible if in English, Danish, French, German, Norwegian, or Swedish. Two authors screened articles by title and abstract, while data extraction from full texts was performed by seven authors using a structured template. Results: A total of 8176 articles were identified, with 1350 selected for full-text review and 268 included in data extraction. Among adults, 187 articles were included, with 88 focused on surgical applications like hip arthroplasty or osteotomy. In pediatrics, 68 general and 13 surgery-related articles were included. Lower extremity analysis was the most frequent topic, with other uses identified, such as rib cage geometry, patellar dislocation, and X-linked hypophosphatemia. Conclusions: Key clinical applications of EOS imaging include lower extremity analysis, e.g., leg length assessment and knee/hip arthroplasty planning), pelvic and spinal alignment studies, and emerging uses in rib cage geometry. Evidence gaps include limited research on the diagnostic accuracy of EOS for cerebral shunt placement, reliability in bone age estimation, and an unclear role in foot and ankle morphology. Full article

The knee is a complex joint essential for locomotion, providing stability that is crucial for avoiding biomechanical deviations such as dynamic knee valgus (DKV), a contributing injury risk factor. This study aimed to assess the influence of body mass index (BMI), age, sex, anthropometric variables, visual feedback, and drop height on the occurrence of DKV. Forty healthy adults aged between 18 and 45 years, with a BMI between 18.5–29.9 kg/m² and no lower limb injuries, were evaluated. Participants underwent a standardized warm-up, anthropometric measurements, and a single-leg drop-landing test from 20 to 30 cm, with and without visual feedback. Women exhibited significantly higher DKV in nearly all conditions. Statistically significant differences were observed between legs when no feedback was provided. Visual feedback significantly reduced DKV in one condition (left limb at 30 cm). Significant weak negative correlations with DKV were found for age, BMI, thigh length, and leg length. These data suggest that women may have higher DKV, anatomical variables may be associated with DKV, and visual feedback may have the potential to attenuate its occurrence. These findings highlight the importance of targeted interventions to attenuate DKV and underscore the role of body awareness and feedback in improving knee alignment. Full article

(1) Background: Dynamic knee valgus (DKV) is a common biomechanical risk factor for knee injuries, particularly in sports involving high-intensity movements, such as basketball. While neuromuscular control and structural alignment contribute to DKV, recent evidence indicates that lower limb muscle power (LLMP) and cardiorespiratory fitness (CRF) may significantly influence DKV. This study aims to examine the relationship among LLMP, CRF, and DKV in adolescent basketball athletes. (2) Methods: A total of 104 adolescent basketball athletes (63.5% boys), 12 to 17 years old (13.87 ± 1.46 years) participated in this study. Anthropometric and demographic characteristics such as sex, age, height, weight, and body mass index (BMI) were recorded. The Counter Movement Jump (CMJ) was used for the evaluation and prediction of the LLMP, the 20 m shuttle run test (20mSRT) was used for the evaluation and prediction of CRF, and the single-leg drop jump (SLDJ) was used for the evaluation of DKV via a two-dimensional (2D) kinematic analysis. Statistical analysis included Pearson and Spearman correlations, as well as multiple linear regression, to determine the relationship among LLMP, CRF, and DKV. (3) Results: A statistical analysis revealed strong correlations among LLMP, CRF, and DKV. Pearson’s correlation coefficients demonstrated significant associations between the VO₂max and frontal plane projection angle (FPPA) (r = 0.78, p < 0.001), as well as between LLMP and FPPA (r = 0.82, p < 0.001). Multiple linear regression analysis showed that VO₂max and LLMP together accounted for 85% of the variance in FPPA (R² = 0.85, p < 0.001). (4) Conclusions: The findings highlight that both aerobic capacity and lower limb muscle power significantly contribute to knee valgus control among adolescent basketball players. Implementing training programs focused on improving lower limb muscle power and cardiorespiratory fitness may enhance knee stability and reduce the risk of lower limb injuries. Given the strong predictive value of VO₂max and LLMP for knee control, targeted training programs focusing on neuromuscular conditioning and aerobic capacity may be effective for injury prevention. Full article

Background: Evidence supporting the validity of photogrammetry for assessing body segment alignment remains limited, with most studies focusing on spinal evaluation. Thus, there is a lack of robust research examining its use for other body segments such as the lower limbs. Objective: This study aimed to evaluate the concurrent validity of three photogrammetric methods for measuring knee alignment in the sagittal plane with and without corrections for potential rotational deviations in the participant’s thigh and leg. Methods: A total of 21 adults underwent sequential evaluations involving panoramic radiography of the lower limbs and photogrammetry at a private radiology clinic. Photogrammetric analysis involved identifying the following anatomical landmarks: the greater trochanter of the femur (GTF), the lateral condyle of the femur (LCF), the head of the fibula (HF), and lateral malleolus (LM). Three photogrammetric methods were employed: (1) the condylar angle (CA) defined by the GTF, LCF, and LM points; (2) the fibula head angle (FHA) defined by the GTF, HF, and LM points; and (3) the four-point angle (4PA) incorporating the GTF, LCF, HF, and LM. Concurrent validity was assessed using correlation analysis, agreement with radiographic measurements, and the root mean square error (RMSE). Each photogrammetric method was tested using raw (CA, FHA, and 4PA) and corrected (CAcorr, FHAcorr, and 4PAcorr) values, accounting for thigh and/or leg rotational deviations. Results: Correcting for thigh and leg rotations significantly improved the validity metrics for all methods. The best performance was observed with the corrected condylar angle (CAcorr: r = 0.746; adjusted r² = 0.533; RMSE = 2.9°) and the corrected four-point angle (4PAcorr: r = 0.733; adjusted r² = 0.513; RMSE = 3.0°); however, the measurements presented proportional errors, possible due the method of assessment of rotations. Conclusions: The findings validate the evaluated photogrammetric methods for assessing sagittal knee alignment. Accounting for thigh and leg rotational deviations is critical for achieving accurate measurements, raising the need of accurate tools for measuring rotational changes in the lower limbs to avoid errors. Full article

Background/Objectives: Limited data exist regarding the influence of total hip arthroplasty (THA) on the alignment of the lower limb. Therefore, the objective of this study was to investigate potential alterations in lower limb alignment (LLA) following total hip arthroplasty, with a focus on the comparison of two different short-stem implant designs. Methods: This retrospective study compares pre- and postoperative hip–knee–ankle angle (HKA), femoral offset, and leg length data of 115 consecutive hips with two different implant types (Mathys Optimys^® stem and Implantec Alpha proxy^® stem). Results: There was not a significant difference between the pre- and postoperative HKA angles regarding the entire study population (p = 0.293), nor after comparing the two short-stem implant designs (p = 0.433). Hip offset almost remained unchanged in the entire study cohort (p = 0.662), as well as when comparing the two short-stem implant designs (p = 0.206). Conclusions: Modern short-stem THA does not significantly affect overall LLA. Full article

Due to its exceptional terrain mobility, quadrupedal locomotion has been used in the design of many amphibious robots for broad applications including resource exploration, disaster rescue, and reconnaissance. In this work, swimming of a quadrupedal paddling model is considered, and the effects of the legs’ initial swing angle, swing amplitude, and power phase duration are numerically investigated through three paddling gaits, namely, the trotting gait, the diagonal, and the lateral sequence gaits. Three different modes for drag-based thrust generation, the “Trotting Mode”, the “Hindering Mode”, and the “Separate Mode”, are identified. In the “Trotting Mode”, each pair of diagonal legs contributes equally and alternately to the thrust within the paddling cycle, and its contribution is impaired by the other pair of diagonal legs. In the “Hindering Mode”, the thrust contribution of an individual leg is significantly undermined by the drag resulting from the preceding leg leaving its current power phase and entering the following recovery phase. In the “Separate Mode”, the four legs independently contribute to the total thrust by forming a compact four-peak waveform equally distributed within one paddling cycle. At a given swing amplitude, the leg configuration at peak thrust moment is identical, regardless of initial swing angle and power phase ratio. Meanwhile, a forward-tilted leg configuration with flatter upper- and lower-limb alignment at peak thrust moment consistently indicates a lower thrust generation. Hydrodynamic moments in the diagonal and lateral sequence gaits are much larger than those in the trotting gait. In addition, enhanced thrust is typically accompanied by larger hydrodynamic moments and a higher energy expenditure. Full article

Background/Objectives: The Chiari pelvic osteotomy (CPO) creates a bony roof by medialization of the acetabulum, thus improving the biomechanics of dysplastic hip joints. Long-term results have already been examined in various studies. However, the impact on the axis of the lower limb has not been investigated yet. The aim of this study was the analysis of changes in the alignment of the lower limb and leg length caused by a CPO and, consecutively, the impact on conversion total hip arthroplasty and primary knee arthroplasty. Methods: A total of 85 patients with 111 CPOs were clinically examined, patient reported outcome measures collected, and long leg standing radiographs analysed according to Paley. Results: The patients were examined an average of 34 years (±7.8; 23–53) after CPO. Unilaterally operated patients (N = 59 hips) showed a pathological MAD in 71% (N = 42) on the operated side (90% valgus, 10% varus). On the unaffected side, we could identify 56% (N = 33 hips) pathological cases (70% valgus, 30% varus). When patients underwent CPO bilaterally (N = 52 hips), the MAD was abnormal in 34 operated hips (65%; 97% valgus, 3% varus). If a leg length discrepancy occurred after the operation, the pelvis and the femur contributed the most to the total leg length discrepancy. Conclusions: Shifts in the mechanical axis following a CPO must be considered in order to inform patients appropriately preoperatively and quantified postoperatively by performing long leg standing radiographs in order to plan following joint replacement therapy adequately and maximize the chance of a successful long-term outcome on a functional level as well as for the patient’s satisfaction. Full article

With the advancement of space exploration and optical communication toward deep space, the high-precision evaluation and image stabilization of space optical payloads under micro-vibration have become increasingly critical. To address these challenges and ensure sub-micro-radian pointing accuracy for high-precision space optical payloads (HPSOPs), this paper proposes a high-precision micro-vibration testing scheme and a two-stage image stabilization system. The micro-vibration testing scheme is based on an automated quasi-zero stiffness suspension device (AQZSSD), which enhances testing sensitivity and environmental disturbance resistance, ensuring the accuracy of the results. The two-stage image stabilization system integrates three bipod vibration isolation legs (BVILs) and a decoupled fast steering mirror (FSM), extending control bandwidth and achieving comprehensive vibration suppression. Micro-vibration testing and image stabilization experiments were conducted under disturbances from multiple vibration sources. Experimental results demonstrate that the AQZSSD introduces disturbances below 0.4 Hz, confirming its quasi-zero stiffness characteristics in alignment with theoretical predictions. Furthermore, the line-of-sight (LOS) jitter root mean square (RMS) value is reduced from 1.253 μrad to 0.276 μrad, achieving sub-micro-radian stability. Additionally, due to the coupling effect of the micro-vibration response, the collaborative testing results were found to be lower than the linear superposition of individual sources. This work offers critical theoretical and technical support for the development of HPSOPs, with potential applications in future space missions and advanced optical technologies. Full article

The ratio of the innate heterophils to the acquired lymphocytes (the H/L-ratio) has been advocated as a good indicator of physiological stress. Little is known, however, about their development in wild birds. The present study investigates how leucocyte profiles develop in nestlings of a long-lived seabird, the Black-legged Kittiwake (Rissa tridactyla). We counted blood leucocytes in nestlings of about 10 and 25 days of age (n = 23), and in breeding adults around the time of hatching (n = 40) and calculated the H/L-ratio for all three groups. We further investigated if any variation in the leucocyte counts could be explained by body condition or the stress-related hormone corticosterone. 10-day-old nestlings in better body condition showed greater investment in heterophils, which increased their H/L-ratio. The initial focus on innate immunity shifted towards acquired immunity by 25 days, aligning their H/L-ratio with that of adults. In adult Kittiwakes, however, better body condition correlated with lower H/L-ratio, the reverse of the pattern in young nestlings, and this variation was not linked to stress hormone (corticosterone) levels. Overall, our findings suggest that the H/L-ratio reflects the ontogeny of physiological traits and individual condition. As an indicator, values must be interpreted depending on age, in which its sensitivity may also vary. As such, the H/L-ratio may not always be a reliable indicator of physiological stress, in particular related to the release of glucocorticoid hormones. Full article

Background/Objectives: This paper proposes a method for managing gait imbalances by integrating the Internet of Things (IoT) and machine learning technologies. Ankle–foot orthosis (AFO) devices are crucial medical braces that align the lower leg, ankle, and foot, offering essential support for individuals with gait imbalances by assisting weak or paralyzed muscles. This research aims to revolutionize medical orthotics through IoT and machine learning, providing a sophisticated solution for managing gait issues and enhancing patient care with personalized, data-driven insights. Methods: The smart ankle–foot orthosis (AFO) is equipped with a surface electromyography (sEMG) sensor to measure muscle activity and an Inertial Measurement Unit (IMU) sensor to monitor gait movements. Data from these sensors are transmitted to the cloud via fog computing for analysis, aiming to identify distinct walking phases, whether normal or aberrant. This involves preprocessing the data and analyzing it using various machine learning methods, such as Random Forest, Decision Tree, Support Vector Machine (SVM), Artificial Neural Network (ANN), Long Short-Term Memory (LSTM), and Transformer models. Results: The Transformer model demonstrates exceptional performance in classifying walking phases based on sensor data, achieving an accuracy of 98.97%. With this preprocessed data, the model can accurately predict and measure improvements in patients’ walking patterns, highlighting its effectiveness in distinguishing between normal and aberrant phases during gait analysis. Conclusions: These predictive capabilities enable tailored recommendations regarding the duration and intensity of ankle–foot orthosis (AFO) usage based on individual recovery needs. The analysis results are sent to the physician’s device for validation and regular monitoring. Upon approval, the comprehensive report is made accessible to the patient, ensuring continuous progress tracking and timely adjustments to the treatment plan. Full article

Objective: This study investigates the impact of age and knee osteoarthritis (OA) on the coronal plane alignment of the lower extremity in Japanese males and females, utilizing the Coronal Plane Alignment of the Knee (CPAK) classification system. Methods: A cross-sectional analysis was conducted with 150 male and 150 female patients. Participants were divided into three groups according to age and OA progression. The mechanical lateral distal femoral angle (mLDFA) and mechanical medial proximal tibial angle (mMPTA) were measured using standard digital long-leg radiographs. Arithmetic hip-knee-ankle angle (aHKA) and joint line obliquity (JLO) were calculated, and the CPAK classification was performed to verify the distribution among the three groups. Results: The results showed increased varus alignment of the mean mLDFA correlated with OA in both genders and with aging in males. The mean mMPTA did not change in males but shifted toward varus in females with both aging and OA. Both genders demonstrated a constitutional varus alignment with the progression of osteoarthritis (males: 1.3 ± 2.4° to −3.5 ± 3.7°, p < 0.001; females: −1.2 ± 3.2° to −3.6 ± 2.9°, p < 0.001). However, this trend with aging was observed only in females (0.0 ± 2.5° to −1.2 ± 3.2°, p = 0.018). JLO maintained its apex distal position with aging and OA progression in all subjects. The study further revealed a notable transition from CPAK Type II to Type I with OA progression in both genders, additionally influenced by aging in females. Conclusions: Aging affects coronal alignment and CPAK classification differently across genders. With OA progression, there was a shift toward smaller aHKA, while JLO remained unchanged. Compared to other races, young Japanese people exhibit similar CPAK distributions, but distinct differences appear in OA-affected individuals, highlighting potential racial variations in CPAK classifications. Full article

Background and Objectives: The Coronal Plane Alignment of the Knee (CPAK) classification is a pragmatic distribution of nine phenotypes for coronal knee alignment that can be used on healthy and arthritic knees. Our study aimed to describe the CPAK distributions in a Spanish southeast osteoarthritic population and compare them to other populations’ published alignment distributions. Method and Materials: Full-leg standing X-rays of the lower limb from 528 cases originating from the so-called Vega Alta del Segura (southeast of the Iberian Peninsula) were retrospectively analysed. We measured the mechanical hip–knee–ankle, lateral distal femoral, and medial proximal tibial angles. We calculated the arithmetic hip–knee–ankle angle and the joint line obliquity to classify each case according to the criteria of the CPAK classification. Results: Based on the aHKA result, 59.1% of the cases were varus (less than −2°), 32.7% were neutral (0° ± 2°), and 8.2% were valgus (greater than +2°). Based on the JLO result, 56.7% of the cases had a distal apex (less than 177°), 39.9% had a neutral apex (180° ± 3°), and 3.4% had a proximal apex (greater than 183°). The most common CPAK distribution in our Spanish southeast osteoarthritic population was type I (30.7%), followed by type IV (25.9%), type II (21%), type V (11.2%), type III (5%), type VI (2.8%), type VII (2.4%), type VIII (0.6%), and type IX (0.4%). Conclusions: We described the distribution according to the CPAK classification in a sample of the osteoarthritic population from southeastern Spain. In our sample, more than 75% of the patients were classified as type I, II, and IV. Full article

The current study aimed to examine (a) whether the dominant leg (DL) was associated with the contralateral side of functional scoliosis and (b) if any of the postural asymmetries’ evaluation variables may be a reliable predictor of the functional scoliosis development in young male soccer players. Six hundred-nine (n = 609) male soccer players (age: 10.8 ± 2.7 years; height: 147 ± 17 cm; weight: 43.4 ± 14.6 kg; DL: Right 81.6%, Left 14%, Both 4.4%) participated in this study. The spinal asymmetries evaluation included thoracic kyphosis, lumbar lordosis, truncal rotation, shoulders alignment from posterior view, anterior and posterior pelvic tilt, anterior superior iliac spine (ASIS), hamstring tightness, and lower extremities discrepancy. A significant association was observed between the DL and the truncal rotation side: χ²(4) = 30.84, p = 0.001, V = 0.16. Participants with longer left legs were likelier to present a spinal asymmetry (OR = 1.18). The participants with higher left shoulders were 2.13 times more likely to have spinal asymmetry than the participants with normal shoulders level. Participants with left ASIS higher were 3.08 times more likely to present asymmetry than those with normally aligned ASIS levels. There was also a significant association between the DL and the side of truncal rotation: χ²(2) = 13.30, p = 0.001, V = 0.449. Logistic regression analysis for the functional scoliotic group and truncal rotation side demonstrated that the taller participants and participants with shorter right legs were more likely to have asymmetry on the left side (OR = 1.29, OR = 0.32). Participants with greater right hamstring stiffness were likelier to have a truncal rotation on the right side (OR = 0.93). Participants with higher left shoulders were 0.20 times less likely to have a truncal rotation on the left side than the participants with normal shoulders level. In conclusion, leg dominance in children and in youth soccer players may be a factor causing truncal rotation on the contralateral side. Additional causes, such as leg length discrepancy and pelvic tilt, may progressively lead to functional scoliosis. Full article

Background: Football, as the most popular sport worldwide, has long been under suspicion of causing varus knee alignment as early as adolescence. However, no causal relationship has yet been found. The first step to do so would be to determine the prevalence of lower leg malalignment among male junior football players depending on age, performance level and the number of active seasons played. Methods: Leg axis alignment in frontal plane was determined in male junior football players of different age levels between 7 and 18 years by measuring the intercondylar/intermalleolar distance (ICD/IMD) in an upright position. In addition to anthropometric data, multiple sport-specific data such as the start of their football career or training time per week were collected by means of questionnaires (clinical trial registration number: DRKS00020446). Results: 207 male junior football players were included in this survey. The mean age was 12.8 years. Within the group of 15 to 18 year olds, the prevalence of varus knee malalignment was highest at just under a third (32.1%). In the subpopulation that played actively for more than ten seasons, 28.9% showed varus leg axis. Regarding performance level, the highest IMD/ICD values and highest prevalence of varus alignment were found among football players who play on a semi-professional level (16.7%), compared to amateur (11.4%) and high-performance levels (2.8%). Conclusions: Further research is necessary to investigate if this high prevalence of varus knee in children of a higher age and higher playing levels is due to the selection bias of football players with varus knee or a real development of varus knee in individuals. Full article