BACKGROUND: Systems that capture motion under laboratory conditions limit validity in real-world environments. Mobile motion capture solutions such as Inertial Measurement Units (IMUs) can progress our understanding of \"real\" human movement. IMU data must be validated in each application to interpret with clinical applicability; this is particularly true for diverse populations. Our IMU analysis method builds on the OpenSim IMU Inverse Kinematics toolkit integrating the Versatile Quaternion-based Filter and incorporates realistic constraints to the underlying biomechanical model. We validate our processing method against the reference standard optical motion capture in a case report with participants with transfemoral amputation fitted with a Percutaneous Osseointegrated Implant (POI) and without amputation walking over level ground. We hypothesis that by using this novel pipeline, we can validate IMU motion capture data, to a clinically acceptable degree.
RESULTS: Average RMSE (across all joints) between the two systems from the participant with a unilateral transfemoral amputation (TFA) on the amputated and the intact sides were 2.35° (IQR = 1.45°) and 3.59° (IQR = 2.00°) respectively. Equivalent results in the non-amputated participant were 2.26° (IQR = 1.08°). Joint level average RMSE between the two systems from the TFA ranged from 1.66° to 3.82° and from 1.21° to 5.46° in the non-amputated participant. In plane average RMSE between the two systems from the TFA ranged from 2.17° (coronal) to 3.91° (sagittal) and from 1.96° (transverse) to 2.32° (sagittal) in the non-amputated participant. Coefficients of Multiple Correlation (CMC) results between the two systems in the TFA ranged from 0.74 to > 0.99 and from 0.72 to > 0.99 in the non-amputated participant and resulted in \'excellent\' similarity in each data set average, in every plane and at all joint levels. Normalized RMSE between the two systems from the TFA ranged from 3.40% (knee level) to 54.54% (pelvis level) and from 2.18% to 36.01% in the non-amputated participant.
CONCLUSIONS: We offer a modular processing pipeline that enables the addition of extra layers, facilitates changes to the underlying biomechanical model, and can accept raw IMU data from any vendor. We successfully validate the pipeline using data, for the first time, from a TFA participant using a POI and have proved our hypothesis.

BACKGROUND: Traditional 3D motion analysis typically considers the spine as a rigid entity. Nevertheless, previous single-joint models have proven inadequate in evaluating the movement across different spinal segments in patients with idiopathic scoliosis (IS). Scoliosis significantly impairs movement functions, especially during activities such as ascending and descending stairs. There is a lack of research on the patterns of stair movement specifically for patients with IS.
OBJECTIVE: This study aims to investigate trunk kinematics in college students with IS during stair ascent and descent tasks. A total of 56 participants, 28 with IS and 28 with healthy controls, were recruited for this case-control study. The trunk movements were analyzed using a motion analysis system that incorporated a multisegment spine model. Understanding the multi-segment spine kinematics during stair tasks can contribute to the development of effective rehabilitation programs for individuals with IS.
METHODS: Case-control study.
METHODS: 28 IS and 28 controls.
METHODS: Cobb angle, spinal curvature, spinal active range of motion (ROM), Kinematics METHODS: The Qualisys system (Gothenburg, Sweden) was utilized in this study with a sampling frequency of 150 Hz. It recorded the kinematics in the thoracic, lumbar, thoracic cage, and pelvis while ascending and descending stairs for both the 28 IS individuals and the 28 control participants. Additionally, clinical parameters such as the Cobb angle, curvature of the spine, spinal range of motion (ROM), and other relevant factors were concurrently assessed among the subjects. Project supported by the National Natural Science Foundation of China (Grant No. 82205306). The authors declare no conflict of interest in preparing this article.
RESULTS: The findings of this study revealed that IS individuals exhibited reduced kyphotic curvature in the sagittal plane (p<.05) when compared to the control group. In contrast, these IS patients displayed greater coronal curvature (Cobb angle) in the frontal plane and a more substantial difference in thoracic side bending range of motion in comparison to the control group (p.05). Moreover, during the ascending stair activity, IS patients showed reduced thoracic cage flexion-extension range of motion (p<.05), while displaying increased lumbar rotation range of motion and anterior-posterior pelvic tilt range of motion (p<.05) in contrast to the control group. Notably, the kinematic analysis during the descent of stairs indicated that IS patients exhibited a larger range of motion in thoracic flexion-extension, thoracic side bending, thoracic cage side bending, thoracic rotation, and thoracic cage rotation when compared to the control group (p<.05).
CONCLUSIONS: The results showed significant differences in trunk kinematics between the two groups during both stair ascent and descent tasks. The utilization of the \"multisegment spine model\" facilitates the acquisition of motion information across multiple segments of the spine in patients diagnosed with IS, effectively enhancing the assessment outcomes derived from imaging information. The three-dimensional structural deformity in the trunk affects both static and dynamic activity patterns. In different activity states, IS patients demonstrate stiff movements in certain segments while experiencing compensatory instability in others. In the future, clinical rehabilitation programs for IS should prioritize stair-related activity training.

Patients with sacroiliac joint dysfunction are limited in daily life activities such as gait, climbing stairs and rising from a chair. It is well known that individuals with chronic low back pain have impaired balance compared to healthy individuals. This cross-sectional case-control study aims to investigate spatiotemporal parameters, center of pressure and mass, pelvic angles and other joint angles in patients with sacroiliac joint dysfunction in comparison with healthy controls.
Motion analysis existed of three tasks: (1) normal gait, (2) single-leg-stance, and (3) sit-to-stance. Spatiotemporal parameters, center of pressure, pelvic angles and other joint angles were measured using a twelve-camera, three-dimensional motion capture system and ground reaction force platforms.
Thirty subjects were recruited for this study; ten patients, ten matched controls and ten healthy student controls. For gait, patients had a lower cadence, longer double support phase, shorter step length and slower walking speed than controls. For single-leg-stance, patients had a smaller hip angle of the risen leg than controls. Also, variability in center of pressure was larger in patients. For sit-to-stance, the total time to perform the task was almost doubled for patients compared to controls.
This study demonstrates that patients with sacroiliac joint dysfunction have an impaired gait, more balance problems during standing and standing up compared to healthy controls. This novel information assists to further comprehend the pathology and disease burden of sacroiliac joint dysfunction, in addition, it may allow us to evaluate the effect of current therapies.

We present the case of an 85-year-old woman who presented to our clinic with neurogenic claudication due to lumbar spinal stenosis (LSS) over a period of two years. During this time a series of walking metrics were monitored including daily step count, walking speed, and step length. All metrics showed a deterioration over time and objectively document the disease progression of LSS (initial: walking speed =1.03 m/s, step length =0.49 m, and daily step count =3,136; final: walking speed =0.49 m/s, step length =0.37 m, and daily step count =334). At this time, the patient had also begun experiencing bilateral lower limb weakness and paraesthesia upon exertion, preventing her from mobilizing for more than a few meters at a time. After a shared decision-making process with the patient and her family, surgical management was recommended. The deterioration of the patient\'s walking metrics matched their increasing requirement for walking assistance, with no walking assistance being needed initially, compared to a four-wheel walker being required in the weeks prior to her surgery. Therefore, the extent of walking deterioration may be able to inform clinical decision-making regarding appropriate walking assistance. To our knowledge, this is the first report that objectively documents the deterioration of LSS using walking metrics for such a prolonged duration of time.

Most of motor recovery usually occurs within the first 3 months after stroke. Herein is reported a remarkable late recovery of the right upper-limb motor function after a left middle cerebral artery stroke. This recovery happened progressively, from two to 12 years post-stroke onset, and along a proximo-distal gradient, including dissociated finger movements after 5 years. Standardized clinical assessment and quantified analysis of the reach-to-grasp movement were repeated over time to characterize the recovery. Twelve years after stroke onset, diffusion tensor imaging (DTI), functional magnetic resonance imaging (fMRI), and transcranial magnetic stimulation (TMS) analyses of the corticospinal tracts were carried out to investigate the plasticity mechanisms and efferent pathways underlying motor control of the paretic hand. Clinical evaluations and quantified movement analysis argue for a true neurological recovery rather than a compensation mechanism. DTI showed a significant decrease of fractional anisotropy, associated with a severe atrophy, only in the upper part of the left corticospinal tract (CST), suggesting an alteration of the CST at the level of the infarction that is not propagated downstream. The finger opposition movement of the right paretic hand was associated with fMRI activations of a broad network including predominantly the contralateral sensorimotor areas. Motor evoked potentials were normal and the selective stimulation of the right hemisphere did not elicit any response of the ipsilateral upper limb. These findings support the idea that the motor control of the paretic hand is mediated mainly by the contralateral sensorimotor cortex and the corresponding CST, but also by a plasticity of motor-related areas in both hemispheres. To our knowledge, this is the first report of a high quality upper-limb recovery occurring more than 2 years after stroke with a genuine insight of brain plasticity mechanisms.

This study demonstrated the use of computerized motion analysis to assist in evidence-based clinical decision-making.
A 15-year-old girl who had right hemiparesis after a stroke was referred for 3-dimensional computerized motion analysis to determine the effect of 3 devices intended to control her dropfoot and to assist in developing a treatment plan. Four conditions were tested and compared: barefoot, lateral support ankle brace, functional electrical stimulation (FES) device, and dropfoot cuff.
Kinematics showed the right ankle had significant dropfoot during swing phase (32.7 degrees of plantarflexion at terminal swing) in barefoot. The lateral support ankle brace, FES device, and dropfoot cuff reduced terminal swing plantarflexion to 27.2 degrees, 17.6 degrees, and 15.3 degrees, respectively, though ankle kinematics remained abnormal because of inadequate dorsiflexion. Improvements in gait variable score with FES (-8.2 degrees) or dropfoot cuff (-8.7 degrees) were significantly more than that with the lateral support brace (-2.2 degrees), and the difference in gait variable score between FES and dropfoot cuff was insignificant. Compared with the barefoot condition, the lateral support brace condition did not show a clinically significant difference in gait profile score; however, the gait profile scores of both FES and dropfoot cuff conditions showed clinically significant improvement (-1.7 degrees and -2.1 degrees, respectively).
Objective data delineated subtle changes among 3 devices and led to the recommendation to discontinue the lateral support ankle brace, continue using her night ankle-foot orthosis and FES device, with the dropfoot cuff as a backup when she feels leg fatigue or skin irritation, and consider serial casting or surgical calf lengthening.
Computerized motion analysis provides quantitative evaluation of subtle differences in the effect of braces with different designs, which are hard for the human eye to discern. The objective data inform and validate treatment decision-making. The recommendations were made as a result of evidence-based practice.

The latest studies of the 30-second sit-to-stand (30-STS) test aim to describe it by employing kinematic variables, muscular activity, or fatigue through electromyography (EMG) instead of a number of repetitions. The aim of the present study was to develop a detection system based on acceleration measured using a smartphone to analyze fatigue during the 30-STS test with surface electromyography as the criterion. This case study was carried out on one woman, who performed eight trials. EMG data from the lower limbs and trunk muscles, as well as trunk acceleration were recorded. Both signals from eight trials were preprocessed, being averaged and temporarily aligned. The EMG signal was processed, calculating the spectral centroid (SC) by Discrete Fourier Transform, while the acceleration signal was processed by Discrete Wavelet Transform to calculate its energy percentage. Regarding EMG, fatigue in the vastus medialis of the quadriceps appeared as a decrease in SC, with a descending slope of 12% at second 12, indicating fatigue. However, acceleration analysis showed an increase in the percentage of relative energy, acting like fatigue firing at second 19. This assessed fatigue according to two variables of a different nature. The results will help clinicians to obtain information about fatigue using an accessible and inexpensive device, i.e., as a smartphone.

In in-vivo motion analyses, data from a limited number of subjects and trials is used as proxy for locomotion properties of entire populations, yet the inherent hierarchy of the individual and population level is usually not accounted for. Despite the increasing availability of hierarchical model frameworks for statistical analyses, they have not been applied extensively to comparative motion analysis. As a case study for the use of hierarchical models, we analyzed locomotor parameters of four Swinhoe\'s striped squirrels. The small-bodied arboreal mammals exhibit brief bouts of rapid asymmetric gaits. Spatio-temporal parameters on runways with experimentally varied dimensions of the setup enclosure were compared to test for their potentially confounding effects. We applied principal component analysis to evaluate changes to the overall locomotor pattern. A common, non-hierarchical, pooled statistical analysis of the data revealed significant differences in some of the parameters depending on enclosure dimensions. In contrast, we used a hierarchical Bayesian generalized linear model (GLM) that considers subject specific differences and population effects to compare the effect of enclosure dimensions on the measured parameters and the principal components. None of the population effects were confirmed by the hierarchical GLM. The confounding effect of a single subject that deviates in its locomotor behavior is potentially bigger than the influence of the experimental variation in enclosure dimensions. Our findings justify the common practice of researchers to intuitively select an enclosure with dimensions assumed as \"non-constraining\". Hierarchical models can easily be designed to cope with limited sample size and bias introduced by deviating behavior of individuals. When limited data is available-a typical restriction of in-vivo motion analyses of non-model organisms-density distributions of the Bayesian GLM used here remain reliable and the hierarchical structure of the model optimally exploits all available information. We provide code to be adjusted to other research questions.

BACKGROUND: Anterior knee pain (AKP) is a common condition, especially in a young active population. The clinical presentations of this condition vary considerably, and therefore, an individualized approach to treatment is needed.
OBJECTIVE: The primary objective of this study was to assess the effect of a novel targeted biomechanical intervention on subjects with AKP.
METHODS: A case series was conducted on 8 participants with AKP.
METHODS: The study was conducted at the Tygerberg Motion Analysis Laboratory and Tygerberg Physiotherapy Clinic in Cape Town, South Africa.
METHODS: Eight subjects (5 females and 3 males) diagnosed with AKP were included in this case series.
METHODS: Participants received a 6-week subject-specific functional movement retraining intervention.
METHODS: Three-dimensional hip, knee, and ankle kinematics were used for analysis for each participant preintervention and postintervention. Pain was measured weekly using the Numeric Pain Rating Scale. Two functional scales (Lower-Extremity Functional Scale and Anterior Knee Pain Scale) were used to assess pain and function the preintervention and postintervention.
RESULTS: All 8 subjects demonstrated improved pain levels (Numeric Pain Rating Scale) and functional outcomes (Anterior Knee Pain Scale and Lower-Extremity Functional Scale). Seven of the 8 participants (87.7%) demonstrated improvements in their main biomechanical outcome.
CONCLUSIONS: A subject-specific functional movement retraining intervention may be successful in the treatment of subjects with AKP presenting with biomechanical risk factors. Research on a larger sample is required to further investigate this approach.

Gait profiles were investigated in a cohort of female pigs experiencing a lameness period prevalence of 29% over 17 months. Gait alterations before and during visually diagnosed lameness were evaluated to identify the best quantitative clinical lameness indicators and early predictors for lameness. Pre-breeding gilts (n= 84) were recruited to the study over a period of 6 months, underwent motion capture every 5 weeks and, depending on their age at entry to the study, were followed for up to three successive gestations. Animals were subject to motion capture in each parity at 8 weeks of gestation and on the day of weaning (28 days postpartum). During kinematic motion capture, the pigs walked on the same concrete walkway and an array of infra-red cameras was used to collect three dimensional coordinate data of reflective skin markers attached to the head, trunk and limb anatomical landmarks. Of 24 pigs diagnosed with lameness, 19 had preclinical gait records, whilst 18 had a motion capture while lame. Depending on availability, data from one or two preclinical motion capture 1-11 months prior to lameness and on the day of lameness were analysed. Lameness was best detected and evaluated using relative spatiotemporal gait parameters, especially vertical head displacement and asymmetric stride phase timing. Irregularity in the step-to-stride length ratio was elevated (deviation  ≥ 0.03) in young pigs which presented lameness in later life (odds ratio 7.2-10.8).