Validation of portable in-clinic video-based gait analysis for prosthesis users.

Despite the common focus of gait in rehabilitation, there are few tools that allow quantitatively characterizing gait in the clinic. We recently described an algorithm, trained on a large dataset from our clinical gait analysis laboratory, which produces accurate cycle-by-cycle estimates of spatiotemporal gait parameters including step timing and walking velocity. Here, we demonstrate this system generalizes well to clinical care with a validation study on prosthetic users seen in therapy and outpatient clinics. Specifically, estimated walking velocity was similar to annotated 10-m walking velocities, and cadence and foot contact times closely mirrored our wearable sensor measurements. Additionally, we found that a 2D keypoint detector pretrained on largely able-bodied individuals struggles to localize prosthetic joints, particularly for those individuals with more proximal or bilateral amputations, but after training a prosthetic-specific joint detector video-based gait analysis also works on these individuals. Further work is required to validate the other outputs from our algorithm including sagittal plane joint angles and step length. Code for the gait transformer and the trained weights are available at https://github.com/peabody124/GaitTransformer .

Improved Trajectory Reconstruction for Markerless Pose Estimation.

Markerless pose estimation allows reconstructing human movement from multiple synchronized and calibrated views, and has the potential to make movement analysis easy and quick, including gait analysis. This could enable much more frequent and quantitative characterization of gait impairments, allowing better monitoring of outcomes and responses to interventions. However, the impact of different keypoint detectors and reconstruction algorithms on markerless pose estimation accuracy has not been thoroughly evaluated. We tested these algorithmic choices on data acquired from a multicamera system from a heterogeneous sample of 53 individuals in a rehabilitation hospital. We found that using a top-down keypoint detector and reconstructing trajectories with an implicit function enabled accurate, smooth, and anatomically plausible trajectories, with a noise in the step width estimates compared to a GaitRite walkway of only 9mm.

Optimizing Trajectories and Inverse Kinematics for Biomechanical Analysis of Markerless Motion Capture Data.

Markerless motion capture using computer vision and human pose estimation (HPE) has the potential to expand access to precise movement analysis. This could greatly benefit rehabilitation by enabling more accurate tracking of outcomes and providing more sensitive tools for research. There are numerous steps between obtaining videos to extracting accurate biomechanical results and limited research to guide many critical design decisions in these pipelines. In this work, we analyze several of these steps including the algorithm used to detect keypoints and the keypoint set, the approach to reconstructing trajectories for biomechanical inverse kinematics and optimizing the IK process. Several features we find important are: 1) using a recent algorithm trained on many datasets that produces a dense set of biomechanically-motivated keypoints, 2) using an implicit representation to reconstruct smooth, anatomically constrained marker trajectories for IK, 3) iteratively optimizing the biomechanical model to match the dense markers, 4) appropriate regularization of the IK process. Our pipeline makes it easy to obtain accurate biomechanical estimates of movement in a rehabilitation hospital.

Resident muscle stem cell myogenic characteristics in postnatal muscle growth impairments in children with cerebral palsy.

Children with cerebral palsy (CP), a perinatal brain alteration, have impaired postnatal muscle growth, with some muscles developing contractures. Functionally, children are either able to walk or primarily use wheelchairs. Satellite cells are muscle stem cells (MuSCs) required for postnatal development and source of myonuclei. Only MuSC abundance has been previously reported in contractured muscles, with myogenic characteristics assessed only in vitro. We investigated whether MuSC myogenic, myonuclear, and myofiber characteristics in situ differ between contractured and noncontractured muscles, across functional levels, and compared with typically developing (TD) children with musculoskeletal injury. Open muscle biopsies were obtained from 36 children (30 CP, 6 TD) during surgery; contracture correction for adductors or gastrocnemius, or from vastus lateralis [bony surgery in CP, anterior cruciate ligament (ACL) repair in TD]. Muscle cross sections were immunohistochemically labeled for MuSC abundance, activation, proliferation, nuclei, myofiber borders, type-1 fibers, and collagen content in serial sections. Although MuSC abundance was greater in contractured muscles, primarily in type-1 fibers, their myogenic characteristics (activation, proliferation) were lower compared with noncontractured muscles. Overall, MuSC abundance, activation, and proliferation appear to be associated with collagen content. Myonuclear number was similar between all muscles, but only in contractured muscles were there associations between myonuclear number, MuSC abundance, and fiber cross-sectional area. Puzzlingly, MuSC characteristics were similar between ambulatory and nonambulatory children. Noncontractured muscles in children with CP had a lower MuSC abundance compared with TD-ACL injured children, but similar myogenic characteristics. Contractured muscles may have an intrinsic deficiency in developmental progression for postnatal MuSC pool establishment, needed for lifelong efficient growth and repair.

Transforming Gait: Video-Based Spatiotemporal Gait Analysis.

Human pose estimation from monocular video is a rapidly advancing field that offers great promise to human movement science and rehabilitation. This potential is tempered by the smaller body of work ensuring the outputs are clinically meaningful and properly calibrated. Gait analysis, typically performed in a dedicated lab, produces precise measurements including kinematics and step timing. Using over 7000 monocular video from an instrumented gait analysis lab, we trained a neural network to map 3D joint trajectories and the height of individuals onto interpretable biomechanical outputs including gait cycle timing and sagittal plane joint kinematics and spatiotemporal trajectories. This task specific layer produces accurate estimates of the timing of foot contact and foot off events. After parsing the kinematic outputs into individual gait cycles, it also enables accurate cycle-by-cycle estimates of cadence, step time, double and single support time, walking speed and step length.

Myelomeningocele: a new functional classification.

PURPOSE: In myelomeningocele, several classifications have been used. The present manuscript proposes a new functional classification to better assess the prognosis and management of these patients. METHODS: The manual muscle test is what defines the actual group in which the patient should be included. Furthermore, this new classification brings information about the bracing and external supports recommended to each functional level. We also recommend that the patient's Functional Mobility Scale should always be mentioned together with their functional level. RESULTS: The four levels in this classification are MMFC1, MMFC2, MMFC3 and MMFC4. The MMFC1 group includes patients with significant muscle weakness. They need to use high braces crossing the hip joint with a walker to achieve some ambulation. The MMFC2 group includes patients who have functional hip flexors, knee extensors and knee flexors. However, the hip abductors are quite weak. These patients usually need to use a walker - or crutches - and Ankle-Foot Orthosis (AFOs). The MMFC3 group includes patients with functional hip flexors, knee extensors, knee flexors and hip abductors. However, the ankle plantar flexion function is absent. Most of them are able to walk independently, only using AFOs without any external support. The MMFC4 group includes patients who have preserved function in the entire lower limb musculature. These patients don't need any assistive devices to achieve an adequate ambulation pattern. CONCLUSIONS: We hope that this new classification is a system that is simple to understand, serves as a gait prognosis guide and facilitates communication among healthcare professionals. LEVEL OF EVIDENCE: V.

Assessment of the Spastic Upper Limb with Computational Motion Analysis.

This article presents the current status of integrating 3-dimensional motion analysis and electromyography to assess upper extremity function clinically. The authors used their approach to establish a normative database for 5 Shriners Hospital Upper Extremity Evaluation tasks, which provides ranges of motion at the point of task achievement. Also, the inter-joint correlations are provided to understand the movement coordination required for each task. Distal upper extremity motion is strongly related to proximal function, supporting the idea that treatment of the proximal upper extremity deficits may be best preceded by treatment of the more distal upper extremity segments.

Hip Power and "Stiff Knee" Gait: A Tool for Identifying Appropriate Candidates for Rectus Transfer.

BACKGROUND: Rectus femoris transfer (RFT) is performed in children with cerebral palsy to treat stiff-knee gait. However, the results are variable in part because there is no gold standard to identify appropriate candidates. Hip flexion kinematics and kinetics are important factors in the determination of peak knee flexion during gait. This study aimed to evaluate whether a kinetic preoperative analysis of hip power can be a predictor of RFT outcomes and determine its usability for identifying appropriate candidates for the procedure. METHODS: Sixteen children with spastic cerebral palsy (20 limbs) GMFCS I/II who underwent RFT for a stiff-knee gait and had preoperative and postoperative 3D gait analyses were retrospectively evaluated. Patient outcomes were classified as "good" or "poor" according to postoperative results. The outcomes were evaluated as a function of (a) 1-parameter criteria-peak hip power (PHP) with a cut-off magnitude≥0.60 W/kg; (b) 2-parameter criteria-PHP (cut-off magnitude≥0.60 W/kg) and the time the PHP occurred during the gait cycle (tPHP), with a cut-off ≤68% of the gait cycle. RESULTS: When the 1-parameter criterion was used, 13 limbs met the criterion; of them, 11 had good outcomes. Seven limbs did not meet the criterion; of them, 6 had poor results (P=0.0049). When the 2-parameter criterion was used, 11 limbs met the criteria; all had good results. Nine limbs did not meet the criterion; of them, 8 had poor results (P=0.0002). PHP+tPHP had the same sensitivity as PHP alone (91%) but with higher specificity (100%) for predicting outcomes. The positive predictive value of magnitude PHP+tPHP was 100%, whereas the accuracy index was 95%. CONCLUSIONS: Preoperative kinetic evaluation of the hip power characteristics from 3D gait analysis appears to be a very important predictor for RFT outcomes and identifying appropriate candidates for the procedure. LEVEL OF EVIDENCE: Level III-therapeutic retrospective study.

Three-dimensional rodent motion analysis and neurodegenerative disorders.

BACKGROUND: Three-dimensional (3D) motion analysis is established in investigating, human pathological motion. In the field of gait, its use results in the objective identification of primary, and secondary causes of deviations, many current interventions are the result of pre- and post-testing, and it was shown recently that it can result in decreased number of surgeries and overall cost of care. Consequently, recent attempts have implemented 3D motion analysis using rat models to study, parkinsonism. However, to-date, a 3D user friendly analytical approach using rodent models to, identify etiologies of age-related motor impairment and accompanying pathologies has not been, implemented. NEW METHOD: We have developed and presented all aspects of a 3D, three body-segment rodent model, to analyze motions of the lower, upper and head segments between rodents of parkinsonism-type and, normal aging during free walking. Our model does not require transformation matrices to describe the, position of each body-segment. Because body-segment positions are not considered to consist of three, rotations about the laboratory axes, the rotations are not sequence dependent. RESULTS: Each body-segment demonstrated distinct 3D movement patterns. The parkinsonism-type, genotype walked slower with less range of motion, similarly to patients with parkinsonism. COMPARISON WITH EXISTING METHODS: This is the first model considering the rodent's body as three, distinct segments. To the best of our knowledge, it is the first model to ever consider and report the 3D, head motion patterns. CONCLUSIONS: This novel approach will allow unbiased analysis of spontaneous locomotion in mouse, models of parkinsonism or normal aging.

Gait characteristics of children with hemiplegic cerebral palsy before and after modified constraint-induced movement therapy.

This investigation assessed selected gait parameters of children with hemiparesis before and after participation in a modified constraint-induced movement therapy program (mCIMT). Recent advances in the understanding of the relationship between mCIMT and cortical reorganization supports the use of upper-extremity mCIMT to treat lower extremity deficits. However, the effects of mCIMT on the gait patterns of children with hemiparesis remain unclear. Twelve preschool children participated in a mCIMT program for 5 consecutive days, 6 h each day. Pre- and post-intervention data, on the temporal-spatial aspects of gait, were collected with the GAITRite walkway. Data were analyzed using a repeated measures generalized linear model. Base of support decreased significantly (p < 0.001) following treatment and improvements were noted in most other gait descriptors. The results of this study suggest that mCIMT can increase stability and improve the overall gait pattern. This study provides a new dimension in the effects of pediatric mCIMT programs and could begin to shift the focus of this intervention to remediation of lower extremity deficits. Additional studies with a longitudinal follow-up focus to determine the long-term effects of mCIMT on walking balance and stability would be beneficial.

Dynamic loading performance of fasciocutaneous flaps and implications for gait.

BACKGROUND: Recent advancements in microsurgery allow the free tissue transfer for reconstruction of soft-tissue defects on the plantar surface of the foot. Fasciocutaneous flaps are one available option to the reconstructive surgeon. However, their functional weight-bearing capabilities have never been adequately evaluated. This study investigated the dynamic loading performance of selected fasciocutaneous flaps during walking using instrumented gait analysis. METHODS: We investigated 6 feet with reconstructed heels along with their contralateral normal feet. A control group of normals was included also. Time-distance, ground reaction force parameters and plantar foot pressure distribution were evaluated. Data were normalized to account for anthropometric variations. A series of t-tests were used to investigate contrasts. FINDINGS: Walking velocity of injured subjects was decreased (P<0.0001). Step length and single limb support were the shortest for the involved feet (P<0.04). Double limb support and swing were the longest (P<0.0002). The reconstructed heels sustained high pressures (P<0.05) and vertical loadings underlining their functional weight-bearing capabilities. However, the walking patterns implemented by the injured subjects resulted in reduced anterior-posterior shear forces that could help maintain the integrity of the shear plane at the graft-recipient bed interface. INTERPRETATION: The dynamic loading capabilities of the fasciocutaneous flaps make it an effective means for restoring functional gait. Patients implement gait patterns that result in primarily decreasing shear forces. Consequently, the fasciocutaneous flaps should be included in the surgeons' armentarium as a plausible reconstructive means for soft-tissue defects on the plantar surface of the foot.