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Background: Segment coordination variability (CV) is a movement pattern associated with running-related injuries. It can also be adversely affected by a prolonged run. However, research on this topic is currently limited. The purpose of this study was to investigate the effects of a prolonged run on segment CV and vertical loading rates during a treadmill half marathon. Methods: Fifteen healthy runners ran a half marathon on an instrumental treadmill in a biomechanical laboratory. Synchronized kinematic and kinetic data were collected every 2 km (from 2 km until 20 km), and the data were processed by musculoskeletal modeling. Segment CVs were computed from the angle-angle plots of selected pelvis-thigh, thigh-shank, and shank-rearfoot couplings using a modified vector coding technique. The loading rate of vertical ground reaction force was also calculated. A one-way MANOVA with repeated measures was performed on each of the outcome variables to examine the main effect of running mileage. Results: Significant effects of running mileage were found on segment CVs (p ≤ 0.010) but not on loading rate (p = 0.881). Notably, during the early stance phase, the CV of pelvis frontal vs. thigh frontal was significantly increased at 20 km compared with the CV at 8 km (g = 0.59, p = 0.022). The CV of shank transverse vs. rearfoot frontal decreased from 2 km to 8 km (g = 0.30, p = 0.020) but then significantly increased at both 18 km (g = 0.05, p < 0.001) and 20 km (g = 0.36, p < 0.001). Conclusion: At the early stance, runners maintained stable CVs on the sagittal plane, which could explain the unchanged loading rate throughout the half marathon. However, increased CVs on the frontal/transverse plane may be an early sign of fatigue and indicative of possible injury risk. Further studies are necessary for conclusive statements in this regard.

• The vertical loading rate was not influenced by running mileages during half marathons. • Changes in coordination variabilities occurred at the early stance phase of running gaits. • As the half marathon progressed, coordination variabilities increased in the couplings of pelvis frontal vs. thigh frontal and shank transverse vs. rearfoot frontal. • The increased coordination variabilities on the frontal/transverse planes of motion could be associated with fatigue and indicate injury potential. Segment coordination variability (CV) is a movement pattern associated with running-related injuries. It can also be adversely affected by a prolonged run. However, research on this topic is currently limited. The purpose of this study was to investigate the effects of a prolonged run on segment CV and vertical loading rates during a treadmill half marathon. Fifteen healthy runners ran a half marathon on an instrumental treadmill in a biomechanical laboratory. Synchronized kinematic and kinetic data were collected every 2 km (from 2 km until 20 km), and the data were processed by musculoskeletal modeling. Segment CVs were computed from the angle-angle plots of selected pelvis-thigh, thigh-shank, and shank-rearfoot couplings using a modified vector coding technique. The loading rate of vertical ground reaction force was also calculated. A one-way MANOVA with repeated measures was performed on each of the outcome variables to examine the main effect of running mileage. Significant effects of running mileage were found on segment CVs (p ≤ 0.010) but not on loading rate (p = 0.881). Notably, during the early stance phase, the CV of pelvis frontal vs. thigh frontal was significantly increased at 20 km compared with the CV at 8 km (g = 0.59, p = 0.022). The CV of shank transverse vs. rearfoot frontal decreased from 2 km to 8 km (g = 0.30, p = 0.020) but then significantly increased at both 18 km (g = 0.05, p < 0.001) and 20 km (g = 0.36, p < 0.001). At the early stance, runners maintained stable CVs on the sagittal plane, which could explain the unchanged loading rate throughout the half marathon. However, increased CVs on the frontal/transverse plane may be an early sign of fatigue and indicative of possible injury risk. Further studies are necessary for conclusive statements in this regard. [Display omitted] [ABSTRACT FROM AUTHOR]

Head‐of‐bed (HOB) elevation is a common clinical practice in hospitals causing the patient's body to slide down in bed because of gravity. This migration effect likely results in tissue shearing between the sacrum and the support surface, which increases the risk for pressure injuries. StayInPlace (HillRom Inc.) is a commercial migration‐reduction technology (MRT) incorporated in intensive care bedframes. Yet, the effects of migration‐reduction on tissue shear stresses during HOB elevation are unknown. We analysed relationships between migration and resulting sacral soft tissue stresses by combining motion analysis and three‐dimensional finite element modelling of the buttocks. Migration data were collected for 10 subjects, lying supine on two bedframe types with and without MRT, and at HOB elevations of 45°/65°. Migration data were used as displacement boundary conditions for the modelling to calculate tissue stress exposures. Migration values for the conventional bed were 1.75‐ and 1.6‐times greater than those for the migration‐reduction bed, for elevations of 45° and 65°, respectively (P <.001). The modelling showed that the farther the migration, the greater the tissue stress exposures. Internal stresses were 1.8‐fold greater than respective skin stresses. Our results, based on the novel integrated experimental‐computational method, point to clear biomechanical benefits in minimising migration using MRT. [ABSTRACT FROM AUTHOR]

Trans-radial prosthesis is a wearable device that intends to help amputees under the elbow to replace the function of the missing anatomical segment that resembles an actual human hand. However, there are some challenging aspects faced mainly on the robot hand structural design itself. Improvements are needed as this is closely related to structure efficiency. This paper proposes a robot hand structure with improved features (four-bar linkage mechanism) to overcome the deficiency of using the cable-driven actuated mechanism that leads to less structure durability and inaccurate motion range. Our proposed robot hand structure also took into account the existing design problems such as bulky structure, unindividual actuated finger, incomplete fingers and a lack of finger joints compared to the actual finger in its design. This paper presents the improvements achieved by applying the proposed design such as the use of a four-bar linkage mechanism instead of using the cable-driven mechanism, the size of an average human hand, five-fingers with completed joints where each finger is moved by motor individually, joint protection using a mechanical stopper, detachable finger structure from the palm frame, a structure that has sufficient durability for everyday use and an easy to fabricate structure using 3D printing technology. The four-bar linkage mechanism is the use of the solid linkage that connects the actuator with the structure to allow the structure to move. The durability was investigated using static analysis simulation. The structural details and simulation results were validated through motion capture analysis and load test. The motion analyses towards the 3D printed robot structure show 70–98% similar motion range capability to the designed structure in the CAD software, and it can withstand up to 1.6 kg load in the simulation and the real test. The improved robot hand structure with optimum durability for prosthetic uses was successfully developed.

Objectives: To determine the concurrent validity of standard clinical outcome measures compared to laboratory outcome measure while performing the weight-bearing lunge test (WBLT).Design: Cross-sectional study.Methods: Fifty participants performed the WBLT to determine dorsiflexion ROM using four different measurement techniques: dorsiflexion angle with digital inclinometer at 15cm distal to the tibial tuberosity (°), dorsiflexion angle with inclinometer at tibial tuberosity (°), maximum lunge distance (cm), and dorsiflexion angle using a 2D motion capture system (°). Outcome measures were recorded concurrently during each trial. To establish concurrent validity, Pearson product-moment correlation coefficients (r) were conducted, comparing each dependent variable to the 2D motion capture analysis (identified as the reference standard). A higher correlation indicates strong concurrent validity.Results: There was a high correlation between each measurement technique and the reference standard. Specifically the correlation between the inclinometer placement at 15cm below the tibial tuberosity (44.9°±5.5°) and the motion capture angle (27.0°±6.0°) was r=0.76 (p=0.001), between the inclinometer placement at the tibial tuberosity angle (39.0°±4.6°) and the motion capture angle was r=0.71 (p=0.001), and between the distance from the wall clinical measure (10.3±3.0cm) to the motion capture angle was r=0.74 (p=0.001).Conclusions: This study determined that the clinical measures used during the WBLT have a high correlation with the reference standard for assessing dorsiflexion range of motion. Therefore, obtaining maximum lunge distance and inclinometer angles are both valid assessments during the weight-bearing lunge test. [ABSTRACT FROM AUTHOR]

At first sight, shoulder mobility is frequently evaluated through mono-axial amplitude. Interestingly, for diagnosing shoulder hyperlaxity or frozen shoulder, external rotation of the arm whilst at the side (ER1) is commonly used. However, by definition, a mono-axial amplitude does not fully reflect shoulder global mobility. Our goal was to propose a novel index for measuring shoulder global mobility and secondly to evaluate the link between main mono-axial amplitudes and this new index. Twenty-eight female subjects (mean age 24.8 years) without upper limb pathology participated in the study. The movements of their right dominant arm were measured with an opto-electronic motion capture system. They performed 5 mono-axial maximal amplitude motions (axial rotations in three different postures, flexion/extension and abduction from rest) and a global range of motion exploring all the reachable space around the three axes of rotation. From this, we computed the correlation coefficient between the volume of the reachable space and each possible linear combination of the 5 mono-axial amplitudes. Even though ER1 is often chosen to assess global mobility, it demonstrated the lowest correlation with measured joint mobility. To assess shoulder global mobility, clinical routine examination should more take into account external/internal rotation with the shoulder abducted, then abduction and finally flexion/extension. However, further clinical testing in other populations has to be done to evaluate the potential generalization of this result. [ABSTRACT FROM AUTHOR]

Anterior superior iliac spine (ASIS) marker occlusion commonly occurs during three-dimensional (3-D) motion capture of dynamic tasks with deep hip flexion. The purpose of this study was to validate a universal technique to correct ASIS occlusion. 420 ms of bilateral ASIS marker occlusion was simulated in fourteen drop vertical jump (DVJ) trials (n = 14). Kinematic and kinetic hip data calculated for pelvic segments based on iliac crest (IC) marker and virtual ASIS (produced by our algorithm and a commercial virtual join) trajectories were compared to true ASIS marker tracking data. Root mean squared errors (RMSEs; mean 7 standard deviation) and intra-class correlations (ICCs) between pelvic tracking based on virtual ASIS trajectories filled by our algorithm and true ASIS position were 2.3±0.9° (ICC=0.982) flexion/extension, 0.8±0.2° (ICC=0.954) abduction/adduction for hip angles, and 0.40±0.17 N m (ICC = 1.000) and 1.05±0.36 N m (ICC=0.998) for sagittal and frontal plane moments. RMSEs for IC pelvic tracking were 6.9±1.8° (ICC=0.888) flexion/extension, 0.8±0.3° (ICC=0.949) abduction/adduction for hip angles, and 0.31±0.13 N m (ICC = 1.00) and 1.48±0.69 N m (ICC=0.996) for sagittal and frontal plane moments. Finally, the commercially-available virtual join demonstrated RMSEs of 4.4±1.5° (ICC=0.945) flexion/extension, 0.7±0.2° (ICC=0.972) abduction/adduction for hip angles, and 0.97±0.62 N m (ICC = 1.000) and 1.49±0.67 N m (ICC=0.996) for sagittal and frontal plane moments. The presented algorithm exceeded the a priori ICC cutoff of 0.95 for excellent validity and is an acceptable tracking alternative. While ICCs for the commercially available virtual join did not exhibit excellent correlation, good validity was observed for all kinematics and kinetics. IC marker pelvic tracking is not a valid alternative. [ABSTRACT FROM AUTHOR]

The purpose of this study was to visualise the locus of the dynamic loading axis on the knee joint, and to evaluate changes in this locus during gait after high tibial osteotomy (HTO) in three patients who underwent HTO for medial compartment osteoarthritis (OA) of a varus knee. The bone structure of the lower limb and the relative position of skin markers were acquired from CT images. Motion capture data was acquired using spherical skin markers. Skeletal model movement during gait was calculated based on the movement of the markers. The locus of the dynamic loading axis on the knee joint was defined as the point on the proximal tibia joint surface that intersected with the loading axis of the lower limb, which passed through the centre of the femoral head and the centroid of multiple points surrounded by the distal tibia joint surface contour. This system was able to visualise the locus of the dynamic loading axis on the knee joint and not only lateral but also anterior–posterior direction movement. After HTO, the locus shifted from a medial and posterior area of the medial joint edge of the knee to a central area of the knee joint surface. This indicates that HTO shifted the dynamic loading axis. Lateral movement of the dynamic loading axis in the early stance phase of gait was reduced within a year after HTO. [Copyright &y& Elsevier]

The purpose of this study was (1) to demonstrate a computer-assisted gait analysis system that can visualize the locus of the dynamic loading axis on the proximal tibia joint surface, and (2) to assess the accuracy of this system in a patient with bilateral knee osteoarthritis (OA). This system uses force plate data, CT skeletal structure data and motion capture data obtained from an infrared position sensor. The relative positions between bones and markers were used to calculate skeletal model movement based on movement of the markers. The locus of the dynamic loading axis on the knee joint was defined as the point on the proximal tibia joint surface that intersected with the loading axis of the lower limb, which passed through the centre of the femoral head and the centroid of multiple points surrounded by the distal tibia joint surface contour. To assess the accuracy of this system, open MRI was used to evaluate positions of skin markers against bones in six healthy volunteers. The locus in a patient was affected by differences between the varus knee with medial compartment OA on the non-operative side and the knee treated with high tibial osteotomy (HTO) on the opposite side. At knee flexion angles of 0°, 15° and 30°, the mean value of measurement error for point locations on the locus was within 5.6% of joint width in the lateral direction (JWLD) on the proximal tibia joint. This system can provide clinically useful information for evaluation of the dynamic loading axis on the knee joint surface. [Copyright &y& Elsevier]

Trans-radial prosthesis is a wearable device that intends to help amputees under the elbow to replace the function of the missing anatomical segment that resembles an actual human hand. However, there are some challenging aspects faced mainly on the robot hand structural design itself. Improvements are needed as this is closely related to structure efficiency. This paper proposes a robot hand structure with improved features (four-bar linkage mechanism) to overcome the deficiency of using the cable-driven actuated mechanism that leads to less structure durability and inaccurate motion range. Our proposed robot hand structure also took into account the existing design problems such as bulky structure, unindividual actuated finger, incomplete fingers and a lack of finger joints compared to the actual finger in its design. This paper presents the improvements achieved by applying the proposed design such as the use of a four-bar linkage mechanism instead of using the cable-driven mechanism, the size of an average human hand, five-fingers with completed joints where each finger is moved by motor individually, joint protection using a mechanical stopper, detachable finger structure from the palm frame, a structure that has sufficient durability for everyday use and an easy to fabricate structure using 3D printing technology. The four-bar linkage mechanism is the use of the solid linkage that connects the actuator with the structure to allow the structure to move. The durability was investigated using static analysis simulation. The structural details and simulation results were validated through motion capture analysis and load test. The motion analyses towards the 3D printed robot structure show 70–98% similar motion range capability to the designed structure in the CAD software, and it can withstand up to 1.6 kg load in the simulation and the real test. The improved robot hand structure with optimum durability for prosthetic uses was successfully developed. [ABSTRACT FROM AUTHOR]