Gait phenotypes in paediatric hereditary spastic paraplegia revealed by dynamic time warping analysis and random forests.
ABSTRACT: The Hereditary Spastic Paraplegias (HSP) are a group of heterogeneous disorders with a wide spectrum of underlying neural pathology, and hence HSP patients express a variety of gait abnormalities. Classification of these phenotypes may help in monitoring disease progression and personalizing therapies. This is currently managed by measuring values of some kinematic and spatio-temporal parameters at certain moments during the gait cycle, either in the doctor´s surgery room or after very precise measurements produced by instrumental gait analysis (IGA). These methods, however, do not provide information about the whole structure of the gait cycle. Classification of the similarities among time series of IGA measured values of sagittal joint positions throughout the whole gait cycle can be achieved by hierarchical clustering analysis based on multivariate dynamic time warping (DTW). Random forests can estimate which are the most important isolated parameters to predict the classification revealed by DTW, since clinicians need to refer to them in their daily practice. We acquired time series of pelvic, hip, knee, ankle and forefoot sagittal angular positions from 26 HSP and 33 healthy children with an optokinetic IGA system. DTW revealed six gait patterns with different degrees of impairment of walking speed, cadence and gait cycle distribution and related with patient's age, sex, GMFCS stage, concurrence of polyneuropathy and abnormal visual evoked potentials or corpus callosum. The most important parameters to differentiate patterns were mean pelvic tilt and hip flexion at initial contact. Longer time of support, decreased values of hip extension and increased knee flexion at initial contact can differentiate the mildest, near to normal HSP gait phenotype and the normal healthy one. Increased values of knee flexion at initial contact and delayed peak of knee flexion are important factors to distinguish GMFCS stages I from II-III and concurrence of polyneuropathy.
Project description:Individuals with cerebral palsy often exhibit crouch gait, a debilitating and inefficient walking pattern marked by excessive knee flexion that worsens with age. To address the need for improved treatment, we sought to evaluate if providing external knee extension assistance could reduce the excessive burden placed on the knee extensor muscles as measured by knee moments. We evaluated a novel pediatric exoskeleton designed to provide appropriately-timed extensor torque to the knee joint during walking in a multi-week exploratory clinical study. Seven individuals (5-19 years) with mild-moderate crouch gait from cerebral palsy (GMFCS I-II) completed the study. For six participants, powered knee extension assistance favorably reduced the excessive stance-phase knee extensor moment present during crouch gait by a mean of 35% in early stance and 76% in late stance. Peak stance-phase knee and hip extension increased by 12° and 8°, respectively. Knee extensor muscle activity decreased slightly during exoskeleton-assisted walking compared to baseline, while knee flexor activity was elevated in some participants. These findings support the use of wearable exoskeletons for the management of crouch gait and provide insights into their future implementation.
Project description:Although several studies have investigated the outcomes after distal hamstring lengthening (DHL), no study has undertaken an approach that included all or most of the important factors that could influence the results. This study was performed to evaluate the outcomes after DHL and analyze the factors that influence the improvement and serial change in knee motion after surgery in patients with cerebral palsy (CP), using a linear mixed model (LMM).The study included 314 ambulatory CP patients (594 limbs) with spsastic diplegia who were followed up after undergoing DHL as part of a single-event multilevel surgery and who underwent preoperative and postoperative 3-dimensional (3D) gait analyses. Relevant kinematic values, including knee flexion at initial contact, minimum knee flexion in the stance phase, knee range of motion (ROM), mean pelvic tilt and gait deviation index (GDI) score, were the outcome measures. Changes in knee motion and the GDI score were adjusted for multiple factors, such as sex, the Gross Motor Function Classification System (GMFCS) level, and concomitant surgeries as fixed effects, and follow-up duration, laterality, and each subject as random effects, using a LMM.We found significant improvements in knee flexion at initial contact, minimum knee flexion in the stance phase, knee ROM, and GDI score 2 years after DHL. In patients with GMFCS level I and II, improvement in all sagittal knee kinematics was maintained during follow-up. In addition, GDI score, which represents overall gait pathology, consistently improved throughout the follow-up duration (1.2 per year, p = 0.008).Medial hamstring lengthening with semitendinosus transfer, as a part of a SEMLS, was effective procedure in treating flexed knee gait with regard to sagittal knee kinematics and GDI score in spastic CP with flexed knee gait.
Project description:Stiff-knee gait is a common walking problem in cerebral palsy characterized by insufficient knee flexion during swing. To identify factors that may limit knee flexion in swing, it is necessary to understand how unimpaired subjects successfully coordinate muscles and passive dynamics (gravity and velocity-related forces) to accelerate the knee into flexion during double support, a critical phase just prior to swing that establishes the conditions for achieving sufficient knee flexion during swing. It is also necessary to understand how contributions to swing initiation change with walking speed, since patients with stiff-knee gait often walk slowly. We analyzed muscle-driven dynamic simulations of eight unimpaired subjects walking at four speeds to quantify the contributions of muscles, gravity, and velocity-related forces (i.e. Coriolis and centrifugal forces) to preswing knee flexion acceleration during double support at each speed. Analysis of the simulations revealed contributions from muscles and passive dynamics varied systematically with walking speed. Preswing knee flexion acceleration was achieved primarily by hip flexor muscles on the preswing leg with assistance from biceps femoris short head. Hip flexors on the preswing leg were primarily responsible for the increase in preswing knee flexion acceleration during double support with faster walking speed. The hip extensors and abductors on the contralateral leg and velocity-related forces opposed preswing knee flexion acceleration during double support.
Project description:Crouch gait, a common walking pattern in individuals with cerebral palsy, is characterized by excessive flexion of the hip and knee. Many subjects with crouch gait experience knee pain, perhaps because of elevated muscle forces and joint loading. The goal of this study was to examine how muscle forces and compressive tibiofemoral force change with the increasing knee flexion associated with crouch gait. Muscle forces and tibiofemoral force were estimated for three unimpaired children and nine children with cerebral palsy who walked with varying degrees of knee flexion. We scaled a generic musculoskeletal model to each subject and used the model to estimate muscle forces and compressive tibiofemoral forces during walking. Mild crouch gait (minimum knee flexion 20-35°) produced a peak compressive tibiofemoral force similar to unimpaired walking; however, severe crouch gait (minimum knee flexion>50°) increased the peak force to greater than 6 times body-weight, more than double the load experienced during unimpaired gait. This increase in compressive tibiofemoral force was primarily due to increases in quadriceps force during crouch gait, which increased quadratically with average stance phase knee flexion (i.e., crouch severity). Increased quadriceps force contributes to larger tibiofemoral and patellofemoral loading which may contribute to knee pain in individuals with crouch gait.
Project description:Patients with acetabular cartilage defects reported increased pain and disability compared to those without acetabular cartilage defects. The specific effects of acetabular cartilage defects on lower extremity coordination patterns are unclear. The purpose of this study was to determine hip and knee joint coordination variability during gait in those with and without acetabular cartilage defects.A combined approach, consisting of a semi-quantitative MRI-based quantification method and vector coding, was used to assess hip and knee joint coordination variability during gait in those with and without acetabular cartilage lesions.The coordination variability of the hip flexion-extension/knee rotation, hip abduction-adduction/knee rotation, and hip rotation/knee rotation joint couplings were reduced in the acetabular lesion group compared to the control group during loading response of the gait cycle. The lesion group demonstrated increased variability in the hip flexion-extension/knee rotation and hip abduction-adduction/knee rotation joint couplings, compared to the control group, during the terminal stance/pre-swing phase of gait.Reduced variability during loading response in the lesion group may suggest reduced movement strategies and a possible compensation mechanism for lower extremity instability during this phase of the gait cycle. During terminal stance/pre-swing, a larger variability in the lesion group may suggest increased movement strategies and represent a compensation or pain avoidance mechanism caused by the load applied to the hip joint.
Project description:The interaction between brain damage and motor function is not yet fully understood in children with spastic cerebral palsy (CP). Therefore, a semi-quantitative MRI (sqMRI) scale was used to explore whether identified brain lesions related to functional abilities and gait pathology in this population. A retrospective cohort of ambulatory children with spastic CP was selected [N = 104; 52 bilateral (bCP) and 52 unilateral (uCP)]. Extent and location-specific scores were defined according to the sqMRI scale guidelines. The gross motor function classification system (GMFCS), the gait profile score (GPS), GPSs per motion plane, gait variable scores (GVS) and multiple-joint (MJ) gait patterns were related to brain lesion scores. In all groups, the global total brain scores correlated to the GPS (total: r s = 0.404, p ? 0.001; bCP: r s = 0.335, p ? 0.05; uCP: r s = 0.493, p ? 0.001). The global total hemispheric scores correlated to the GMFCS (total: r s = 0.392, p ? 0.001; bCP: r s = 0.316, p ? 0.05; uCP: r s = 0.331, p ? 0.05). The laterality scores of the hemispheres in the total group correlated negatively to the GMFCS level (r s = -0.523, p ? 0.001) and the GVS-knee sagittal (r s = -0.311, p ? 0.01). Lesion location, for the total group demonstrated positive correlations between parietal lobe involvement and the GPS (r s = 0.321, p ? 0.001) and between periventricular layer damage and the GMFCS (r s = 0.348, p ? 0.001). Involvement of the anterior part of the corpus callosum (CC) was associated with the GVS-hip sagittal in all groups (total: r pb = 0.495, p ? 0.001; bCP: r pb = 0.357, p ? 0.05; uCP: r pb = 0.641, p ? 0.001). The global total hemispheric and laterality of the hemispheres scores differentiated between the minor and both the extension (p ? 0.001 and p ? 0.001) and flexion (p = 0.016 and p = 0.013, respectively) MJ patterns in the total group. Maximal periventricular involvement and CC intactness were associated with extension patterns (p ? 0.05 and p ? 0.001, respectively). Current findings demonstrated relationships between brain structure and motor function as well as pathological gait, in this cohort of children with CP. These results might facilitate the timely identification of gait pathology and, ultimately, guide individualized treatment planning of gait impairments in children with CP.
Project description:BACKGROUND:Gait analysis can be used to measure variations in joint function in patients with knee osteoarthritis (OA), and is useful when observing longitudinal biomechanical changes following Total Knee Replacement (TKR) surgery. The Cardiff Classifier is an objective classification tool applied previously to examine the extent of biomechanical recovery following TKR. In this study, it is further developed to reveal the salient features that contribute to recovery towards healthy function. METHODS:Gait analysis was performed on 30 patients before and after TKR surgery, and 30 healthy controls. Median TKR follow-up time was 13 months. The combined application of principal component analysis (PCA) and the Cardiff Classifier defined 18 biomechanical features that discriminated OA from healthy gait. Statistical analysis tested whether these features were affected by TKR surgery and, if so, whether they recovered to values found for the controls. RESULTS:The Cardiff Classifier successfully discriminated between OA and healthy gait in all 60 cases. Of the 18 discriminatory features, only six (33%) were significantly affected by surgery, including features in all three planes of the ground reaction force (p<0.001), ankle dorsiflexion moment (p<0.001), hip adduction moment (p = 0.003), and transverse hip angle (p = 0.007). All but two (89%) of these features remained significantly different to those of the control group after surgery. CONCLUSIONS:This approach was able to discriminate gait biomechanics associated with knee OA. The ground reaction force provided the strongest discriminatory features. Despite increased gait velocity and improvements in self-reported pain and function, which would normally be clinical indicators of recovery, the majority of features were not affected by TKR surgery. This TKR cohort retained pre-operative gait patterns; reduced sagittal hip and knee moments, decreased knee flexion, increased hip flexion, and reduced hip adduction. The changes that were associated with surgery were predominantly found at the ankle and hip, rather than at the knee.
Project description:BACKGROUND AND OBJECTIVES:Virtual reality (VR) is increasingly often finding applications in physiotherapy and health promotion. Recent years have seen the use of advanced technologies in the promotion of physical activity (PA) in society. New simulators, e.g., treadmills, enable the performance of PA (e.g., locomotive movements) in VR (artificially created virtual world). The question of how such movements are similar to natural forms of human locomotion (march, run) inspired the comparative analysis of physiological gait and gait in VR on a multidirectional Omni treadmill. MATERIALS AND METHODS:The tests involved the use of the BTS Smart system for the triplanar analysis of motion. The test involved 10 healthy females aged 20-24 (weight: 52 ± 3.1 kg, height 162 ± 5.4 cm). Measurements were performed at two stages. The first stage involved the standard assessment of physiological gait, whereas the second was focused on gait forced by the Omni treadmill. The following gait parameters were analyzed: Flexion-extension in the ankle, knee joint and hip joint, rotation in the hip joint and knee joint, foot progression, adduction-abduction in the knee joint and hip joint, pelvic obliquity, pelvic tilt, pelvic rotation as well as energy expenditure and the movement of the body center of mass. RESULTS:The analysis of the test results revealed the existence of differences in the kinematics of physical gait and gait on the treadmill. The greatest differences were recorded in relation to the dorsal-plantar flexion in the ankle, the foot progression, the rotation of the knee joint, pelvic tilt and rotation. In addition, the gait on the treadmill is characterized by the longer duration of the stance phase and reduced ranges of the following movements: Flexion-extension in the ankle, knee joint and hip joint, adduction-abduction in the hip joint as well as rotation in the ankle and hip joint. The values of potential, kinetic and total energy recorded in relation to forced gait are significantly lower than those of physiological gait. CONCLUSIONS:Because of the fact that the parameters of gait on the Omni platform vary significantly from the parameters of physical gait, the application of the Omni treadmill in the re-education of gait during rehabilitation should be treated with considerable care. Nonetheless, the treadmill has adequate potential to become a safe simulator enabling active motion in VR using locomotive movements.
Project description:Rectus femoris transfer surgery is a common treatment for stiff knee gait in children with cerebral palsy. Unfortunately, the improvement in knee motion after surgery is inconsistent. There is great interest in understanding the causes of stiff knee gait and determining predictors of improved knee motion after surgery. This study demonstrates that it is possible to predict whether or not a patient's knee motion will improve following rectus femoris transfer surgery with greater than 80% accuracy. A predictive model was developed that requires only a few preoperative gait analysis measurements, already collected as a routine part of treatment planning. Our examination of 62 patients before and after rectus femoris transfer revealed that a combination of hip power, knee power, and knee flexion velocity at toe-off correctly predicted postoperative outcome for 80% of cases. With the addition of two more preoperative measurements, hip flexion and internal rotation, prediction accuracy increased to nearly 88%. Other combinations of preoperative gait analysis measurements also predicted outcomes with high accuracy. These results provide insight into factors related to positive outcomes and suggest that predictive models provide a valuable tool for determining indications for rectus femoris transfer.
Project description:Existent biomechanical studies on hip osteoarthritic gait have primarily focused on the end stage of disease. Consequently, there is no clear consensus on which specific gait parameters are of most relevance for hip osteoarthritis patients with mild to moderate symptoms. The purpose of this study was to explore sagittal plane gait characteristics during the stance phase of gait in hip osteoarthritis patients not eligible for hip replacement surgery. First, compared to healthy controls, and second, when categorized into two subgroups of radiographic severity defined from a minimal joint space of ?/>2 mm.Sagittal plane kinematics and kinetics of the hip, knee and ankle joint were calculated for total joint excursion throughout the stance phase, as well as from the specific events initial contact, midstance, peak hip extension and toe-off following 3D gait analysis. In addition, the Western Ontario and McMaster Universities Osteoarthritis Index, passive hip range of motion, and isokinetic muscle strength of hip and knee flexion and extension were included as secondary outcomes. Data were checked for normality and differences evaluated with the independent Student's t-test, Welch's t-test and the independent Mann-Whitney U-test. A binary logistic regression model was used in order to control for velocity in key variables.Fourty-eight hip osteoarthritis patients and 22 controls were included in the final material. The patients walked significantly slower than the controls (p=0.002), revealed significantly reduced joint excursions of the hip (p<0.001) and knee (p=0.011), and a reduced hip flexion moment at midstance and peak hip extension (p<0.001). Differences were primarily manifested during the latter 50% of stance, and were persistent when controlling for velocity. Subgroup analyses of patients with minimal joint space ?/>2 mm suggested that the observed deviations were more pronounced in patients with greater radiographic severity. The biomechanical differences were, however, not reflected in self-reported symptoms or function.Reduced gait velocity, reduced sagittal plane joint excursion, and a reduced hip flexion moment in the late stance phase of gait were found to be evident already in hip osteoarthritis patients with mild to moderate symptoms, not eligible for total hip replacement. Consequently, these variables should be considered as key features in studies regarding hip osteoarthritic gait at all stages of disease. Subgroup analyses of patients with different levels of radiographic OA further generated the hypothesis that the observed characteristics were more pronounced in patients with a minimal joint space ?2 mm.