Bruce Carse

Affordable clinical gait analysis: an assessment of the marker tracking accuracy of a new low-cost optical 3D motion analysis system

BACKGROUND 3D motion analysis represents a method of collecting objective, accurate and repeatable gait data, however the high cost of equipment inhibits its widespread use in routine clinical practice. OBJECTIVE To determine the marker tracking accuracy of a new low-cost optical 3D motion analysis system. DESIGN Comparative between-system study. SETTING Clinical motion analysis laboratories. METHODS A rigid cluster of four reflective markers was used to compare a low-cost Optitrack 3D motion analysis system against two more expensive systems (Vicon 612 and Vicon MX). Accuracy was measured by comparing the mean vector magnitudes (between each combination of markers) for each system, and reliability was measured through the coefficients of variation (CV). Gaps in the marker trajectories, which are considered undesirable, were also counted. RESULTS In terms of accuracy, the largest disagreement between mean vector magnitudes for Optitrack and Vicon MX was 2.2%. The largest disagreement between Vicon 612 and Vicon MX was 2.1%. Regarding reliability, the mean CV was lowest in Vicon MX (0.3%) and similar in the Vicon 612 (2.5%) and Optitrack (2.3%) systems. The number of trajectory gaps for the Vicon MX, Vicon 612 and Optitrack systems were; zero, six and 11 respectively. CONCLUSIONS The Optitrack system provides a low-cost 3D motion analysis system that can offer marker tracking accuracy and reliability which is comparable with an older and still widely used system (Vicon 612). Further development work is required before Optitrack can be used for full 3D gait analysis by physiotherapists and other health professionals.

Developing visualisation software for rehabilitation: Investigating the requirements of patients, therapists and the rehabilitation process

This article describes the ongoing process of engaging with users in the development and evaluation of prototype visualisation software, which aims to assist in the understanding and improvement of appropriate movements during rehabilitation. The value of the process is illustrated in the article with a discussion of the key findings of pre-pilot focus groups with stroke survivors and therapists. The article describes how the design of the visualisation software is being adapted to meet the emerging understanding of the needs of patients and professionals, and of the rehabilitation process.

Autonomous Gait Event Detection with Portable Single-Camera Gait Kinematics Analysis System

Laboratory-based nonwearable motion analysis systems have significantly advanced with robust objective measurement of the limb motion, resulting in quantified, standardized, and reliable outcome measures compared with traditional, semisubjective, observational gait analysis. However, the requirement for large laboratory space and operational expertise makes these systems impractical for gait analysis at local clinics and homes. In this paper, we focus on autonomous gait event detection with our bespoke, relatively inexpensive, and portable, single-camera gait kinematics analysis system. Our proposed system includes video acquisition with camera calibration, Kalman filter

Use of biomechanical data in the Inclusive Design process: packaging design and the older adult

Biomechanical data may be used to inform the design process to ensure Inclusive Design. Yet many products are clearly not designed inclusively, one possible reason being that biomechanical data are not used, is not available or offers insufficient benefits to merit integration into the design process. This study investigates designers’ use of biomechanical data to inform the process of Inclusive Design in the consumer packaging industry. Packaging design professionals were interviewed to elicit information regarding their use of biomechanical data and to establish if they followed Inclusive Design principles. Biomechanical data were collected using observational study and customised force and motion measurement tools. Finally, biomechanical data were presented to the designers to establish the best/preferred format for use in the design process. Biomechanical data were rarely used by the designers and Inclusive Design principles were not routinely incorporated into company procedures. There was clear preference for visual data with imagery of real subjects. Most quantitative force and motion data formats were considered to be unsuitable for routine use due to commercial priorities and lack of technical appreciation. The use of biomechanical testing to develop standards to allow Inclusive Design may be the way forward.

The immediate effects of fitting and tuning solid ankle–foot orthoses in early stroke rehabilitation

Background: Ankle-foot orthoses are known to have a generally positive effect on gait in stroke, however the specifc type of AFO and the time point at which it is provided are highly variable in the currently available literature. Objective: The objective was to determine the immediate spatiotemporal and kinematic effect of custom-made solid ankle–foot orthoses in early stroke rehabilitation, compared to shod walking. Methods: Five male and three female participants were recruited to the study (n = 8), with a mean age of 57 (16) years who were 3.5 (3) weeks post-stroke. Each received a custom-made solid ankle–foot orthosis to a predefined set of design criteria and tuned using heel wedges to control the shank inclination angle during shod walking. Repeated spatiotemporal and three-dimensional gait measures were taken pre- and immediately post-intervention. Study design: A pre–post-test experimental study. Results: With the solid ankle–foot orthosis, walking velocity increased from 0.22 (0.2) to 0.36 (0.3) m/s (p < 0.05), overall average step length increased from 0.28 (0.1) to 0.37 (0.1) m (p < 0.05), cadence increased from 45 (19) to 56 (19) steps/min (p < 0.05) and step length symmetry ratio increased from 0.65 (0.2) to 0.74 (0.2) (not significant). No clear changes were observed in the joint kinematics of the hip and knee. Conclusion: In our small group of early stroke patients who were fitted with a solid ankle–foot orthosis, immediate significant improvements occurred in walking speed, step length and cadence, when compared to walking with shoes only. Clinical relevance This study provides evidence about the immediate effects of custom solid ankle–foot orthoses on gait of early stroke survivors. Ankle–foot orthosis design specifications are fully described for replication. This study suggests that observing global segment orientation may be more useful than joint angles when fitting and tuning ankle–foot orthoses for optimal ankle–foot orthosis/footwear alignment.

Multiple marker tracking in a single-camera system for gait analysis

Human gait analysis for stroke rehabilitation therapy using video processing tools has become popular in recent years. This paper proposes a single-camera system for capturing gait patterns using a Kalman-Structural-Similarity-based algorithm which tracks multiple markers simultaneously. This algorithm is initialized by obtaining the user-selected blocks in the first frame of each video, and the tracker is implemented by using Structural-Similarity image quality assessment algorithm to detect each marker frame by frame within a search area determined by a discrete Kalman filter. Experimental results show the trajectories of the markers fixed on the joints of a human body. The obtained numerical results are used to generate gait information (e.g., knee joint angle) that is later used for diagnostics. The proposed method aims to explore an alternative and portable way to implement human gait analysis with significantly less cost compared to a state-of-the-art 3D motion capture system.

Visualisation to enhance biomechanical tuning of ankle-foot orthoses (AFOs) in stroke: study protocol for a randomised controlled trial

BackgroundThere are a number of gaps in the evidence base for the use of ankle-foot orthoses for stroke patients. Three dimensional motion analysis offers an ideal method for objectively obtaining biomechanical gait data from stroke patients, however there are a number of major barriers to its use in routine clinical practice. One significant problem is the way in which the biomechanical data generated by these systems is presented. Through the careful design of bespoke biomechanical visualisation software it may be possible to present such data in novel ways to improve clinical decision making, track progress and increase patient understanding in the context of ankle-foot orthosis tuning.MethodsA single-blind randomised controlled trial will be used to compare the use of biomechanical visualisation software in ankle-foot orthosis tuning against standard care (tuning using observation alone). Participants (n = 70) will have experienced a recent hemiplegia (1-12 months) and will be identified by their care team as being suitable candidates for a rigid ankle-foot orthosis. The primary outcome measure will be walking velocity. Secondary outcome measures include; lower limb joint kinematics (thigh and shank global orientations) & kinetics (knee and hip flexion/extension moments, ground reaction force FZ2 peak magnitude), step length, symmetry ratio based on step length, Modified Ashworth Scale, Modified Rivermead Mobility Index and EuroQol (EQ-5D). Additional qualitative measures will also be taken from participants (patients and clinicians) at the beginning and end of their participation in the study. The main aim of the study is to determine whether or not the visualisation of biomechanical data can be used to improve the outcomes of tuning ankle-foot orthoses for stroke patients.DiscussionIn addition to answering the primary research question the broad range of measures that will be taken during this study are likely to contribute to a wider understanding of the impact of ankle-foot orthoses on the lives of stroke patients.Trial registration numberISRCTN: ISRCTN52126764

Investigating the Use of Visualisations of Biomechanics in Physical Rehabilitation

Biomechanical analysis can be used to scientifically assess the causes of movement problems, measure progress and validate outcomes. However, the complexity of the data produced and the training required to use the available biomechanical analysis tools prevents the widespread understanding of this form of analysis beyond those with a background in biomechanics. This paper reports on multidisciplinary research, funded by the MRC’s LLHW programme, into the generation of three-dimensional, dynamic visualisations of biomechanical data and investigation of their use during functional rehabilitation trials, e.g., post-stroke, knee-joint replacement, and older adult exercise. The research will test the hypothesis that increased understanding of biomechanical concepts and measurements through this method of visualisation by both patients and clinicians will result in better patient outcomes.

The use of biomechanical visualisation in neurorehabilitation and its effect on ankle-foot orthosis (AFO) tuning in stroke

Background: Difficulties interpreting the biomechanical data captured by 3D gait analysis (3DGA) systems mean that it is rarely used in routine clinical practice for gait rehabilitation of stroke patients. Biomechanical visualisation software has been designed to make data clinically useful in the context of AFO fitting and tuning for stroke patients. Therapists can use objective quantitative data to assist clinical decision-making. Participants receive an improved understanding of their condition/treatment, and it allows progress tracking. Objective: Test the hypothesis that stroke patients will receive improved outcomes when biomechanics visualisation is used in the AFO fitting and tuning process. Patients and methods/material and methods: An RCT is being used (ISRCTN52126764). The intervention arm receive AFO fitting and tuning using 3DGA and visualisation, and the non-intervention arm receive an AFO by standard care (clinicians using observation). Walking velocity, 3D kinematics and kinetics, step length, gait symmetry, mRMI and EuroQol (EQ-5L-5D) are measured at four time points (baseline, AFO provision, three months and six months). Ten participants, 5.7(6) weeks post-stroke, with an average age of 56.4(17) years have been recruited. Results: Walking velocity improvement (before/after AFO provision) data for the intervention group (n = 5) was 22(21) cm/s versus 1.6(6.4) cm/s for the non-intervention group (n = 5). The difference is significant (p < 0.05, Mann–/INS;Whitney U Test). More extensive results will be available at the time of presentation. Conclusion: Early data indicate that the visualisation of biomechanical data appears to assist the AFO tuning process, providing stroke patients with better immediate improvements in walking velocity.