Richard Baker

University of Salford · Centre for Health Sciences Research

Background To be able to use muscluloskeletal models in clinical settings, it is important to understand the effect of walking speed on joint and muscle force estimations in different generic musculoskeletal models. Research question The aim of the current study is to compare estimated joint and muscle forces as a function of walking speed between...

Background The spring-mass model is commonly used to investigate the mechanical characteristics of human running. Underlying this model is the assumption of a linear force-length relationship, during the stance phase of running, and the idea that stiffness can be characterised using a single spring constant. However, it remains unclear whether the...

High functioning military transtibial amputees (TTAs)with well‐fitted state of the art prosthetics have gait that is indistinguishable from healthy individuals, yet they are more likely to develop knee osteoarthritis (OA)of their intact limbs. This contrasts with the information at the knees of the amputated limbs that has been shown to be at a sig...

Background: The Conventional Gait Model (CGM), known by a variety of different names, is widely used in clinical gait analysis. We present pyCGM2, an open-source implementation of the CGM with two versions. The first, CGM1.0, is a clone of Vicon Plug In Gait (PiG) with all its variants. CGM1.0 provides a platform to test the effect of modification...

Background: The Conventional Gait Model (CGM), known by a variety of different names, is widely used in clinical gait analysis. We present pyCGM2, an open-source implementation of the CGM with two versions. The first, CGM1.0, is a clone of Vicon Plug In Gait (PiG) with all its variants. CGM1.0 provides a platform to test the effect of modifications...

A variety of musculoskeletal models are applied in different modelling environments for estimating muscle forces during gait. Influence of different modelling assumptions and approaches on model outputs are still not fully understood, while direct comparisons of standard approaches have been rarely undertaken. This study seeks to compare joint kine...

Objectives: Muscle force estimation could enhance clinical movement analysis by giving insight into causes of impairments and informing targeted treatments. However, muscle force estimation is not typically used in this way due to difficulties in validation and selection of clinically adequate models. Estimated muscle forces are depend on its muscl...

Mathematical models have the potential to provide insight into human running. Existing models can be categorised as either simple or complex, and there appears to be a lack of natural progression in model development. By sequentially adding complexity, there is the potential to determine how different mechanical components contribute to the biomech...

Background: Target-stepping paradigms are increasingly used to assess and train gait adaptability. Accurate gait-event detection (GED) is key to locating targets relative to the ongoing step cycle as well as measuring foot-placement error. In the current literature GED is either based on kinematics or centre of pressure (CoP), and both have been p...

In musculoskeletal modelling of walking, the ankle is often simplified, e.g. restricting the degree of freedom (DoF) of the ankle joint, which might lead to altered muscle force estimations. The aim of the study is to understand the impact of the ankle's degree of freedom on muscle force estimation using different modelling environments. Two standa...

Introduction Knowing the force profiles of individual muscles may help to better identify various neuro-musculoskeletal impairments. Patellofemoral pain, for example, is often thought [1] to be caused by an imbalance of force between agonist and antagonist muscles and can lead to excessive loading of the knee joint and subsequent risk of developing...

Introduction A range of modelling approaches have already been applied related to sport performance or clinical interventions. However, modelling of muscle forces or muscle activation is not typically used routinely in a clinical setting due to difficulties in validation and selection of clinically adequate models. Research Question This study se...

Background: Muscle force estimation could improve clinical gait analysis by enhancing insight into causes of impairments and informing targeted treatments. However, it is not currently standard practice to use muscle force models to augment clinical gait analysis, partly, because robust validations of estimated muscle activations, underpinning for...

Winter first measured the velocity of a marker placed on the distal heel at foot contact during walking and concluded that this was virtually zero in the vertical direction and low in the horizontal direction (1) questioning the relevance of the term 'heel strike'. He suggested a number of late swing mechanisms which have the potential to achieve t...

Computational methods to estimate muscle forces during walking are becoming more common in biomechanical research but not yet in clinical gait analysis. This systematic review aims to identify the current state-of-the-art, examine the differences between approaches, and consider applicability of the current approaches in clinical gait analysis. A s...

Inverse kinematics is emerging as the optimal method in movement analysis to fit a multi-segment biomechanical model to experimental marker positions. A key part of this process is calibrating the model to the dimensions of the individual being analysed which requires scaling of the model, pose estimation and localisation of tracking markers within...

Background: Education and training in prosthetics and orthotics typically comply with International Society for Prosthetics and Orthotics standards based on three categories of prosthetic and orthotic professionals. Objective: This scoping study sought to describe the evidence base available to answer the question, How are prosthetic and orthoti...

Objectives: Standards and guidelines are an integral part of prosthetic and orthotic service delivery in the developed world underpinned by an assumption that they lead to improved services. Implementing them has a cost, however, and that cost needs to be justified, particularly in resource-limited environments. This scoping review thus asks the qu...

Knowing the force profiles of individual muscles during various functional tasks may help to better identify various neuro-musculoskeletal impairments from functional movement analysis. Different simulation environments exist for this purpose. The aim of this study was to compare gait muscle force estimations (static optimisation) between the simul...

The Conventional Gait Model (CGM) is a generic name for a family of closely related and very widely used biomechanical models for gait analysis. After describing its history, the core attributes of the model are described followed by evaluation of its strengths and weaknesses. An analysis of the current and future requirements for practical biomech...

Simple 2D models of walking often approximate the human body to multi-link dynamic systems, where body segments are represented by rigid links connected by frictionless hinge joints. Performing forward dynamics on the equations of motion (EOM) of these systems can be used to simulate their movement. However, deriving these equations can be time con...

Clinical gait analysis incorporating three-dimensional motion analysis plays a key role in planning surgical treatments in people with gait disability. The position of the Hip Joint Centre (HJC) within the pelvis is thus critical to ensure accurate data interpretation. The position of the HJC is determined from regression equations based on anthrop...

Reduced capacity and increased metabolic cost of walking occurs in amputees, despite advances in prosthetic componentry. Joint powers can quantify deficiencies in prosthetic gait, but do not reveal how energy is exchanged between limb segments. This study aimed to quantify these energy exchanges during amputee walking. Optical motion and forceplate...

Introduction Le centre articulaire de la hanche (CAH) du modèle conventionnel de marche (MCM), développé par Davis s’appuie sur des régressions construites à l’aide d’un faible nombre de pelvis. L’imprécision de cette régression a été constatée au moyen de l’imagerie médicale 3D. De nouvelles régressions sont disponibles, mais aucune ne quantifie l...

Objective: To record the temporal spatial parameters and metabolic energy expenditure during walking of individuals with amputation, walking with advanced prostheses, and after completion of comprehensive rehabilitation compared with able-bodied persons. Design: Cross-sectional. Setting: Multidisciplinary comprehensive rehabilitation center....

Amputees are known to walk with greater metabolic cost than able-bodied individuals and establishing predictors of metabolic cost from kinematic measures, such as centre of mass (CoM) motion, during walking are important from a rehabilitative perspective, as they can provide quantifiable measures to target during gait rehabilitation in amputees. Wh...

Gait analysis is a well-established tool for the quantitative assessment of gait disturbances providing functional diagnosis, assessment for treatment planning, and monitoring of disease progress. There is a large volume of literature on the research use of gait analysis, but evidence on its clinical routine use supports a favorable cost-benefit ra...

A primary source of measurement error in gait analysis is soft-tissue artefact. Hip and knee angle measurements, regularly used in clinical decision-making, are particularly prone to pervasive soft tissue on the femur. However, despite several studies of thigh marker artefact it remains unclear how lateral thigh marker height affects results using...

Normalizing clinical gait analysis data is required to remove variability due to physical characteristics such as leg length and weight. This is particularly important for children where both are associated with age. In most clinical centres conventional normalization (by mass only) is used whereas there is a stronger biomechanical argument for non...

Background Children with cerebral palsy (CP) often have an altered gait. Orthopaedic surgery, spasticity management, physical therapy and orthotics are used to improve the gait. Interventions are individually tailored and are planned on the basis of clinical examinations and standardised measurements to assess walking (‘care as usual’). However, th...

Aim: We compared two botulinum toxin A (BoNT-A) injection frequency regimens, 12-monthly versus 4-monthly, for spastic equinus in a randomized clinical trial. The primary outcome measure was passive ankle dorsiflexion. Method: Forty-two ambulant children with spastic equinus, secondary to cerebral palsy (23 males and 19 females; mean age 3y 6mo,...

Mathematical gait models often fall into one of two categories: simple and complex. There is a large leap in complexity between model types, meaning the effects of individual gait mechanisms get overlooked. This study investigated the cause-and-effect relationships between gait mechanisms and resulting kinematics and kinetics, using a sequence of m...

To examine if individualised resistance training increases the daily physical activity of adolescents and young adults with bilateral spastic cerebral palsy (CP). Young people with bilateral spastic CP were randomly assigned to intervention or to usual care. The intervention group completed an individualised lower limb progressive resistance traini...

Due to known limitations and missing standardised protocols muscle force modelling is not established yet in the classical gait analysis. A better understanding of these limitations and the development of such a protocol is needed. The project aims to achieve this by using SimTrack within OpenSim. Muscle activations and forces of healthy normative...

An investigation into the kinematic and kinetic predictions of two “inverted pendulum” (IP) models of gait was undertaken. The first model consisted of a single leg, with anthropometrically correct mass and moment of inertia, and a point mass at the hip representing the rest of the body. A second model incorporating the physiological extension of a...

INTRODUCTION and AIM The effects of bilateral subthalamic nucleus (STN) deep brain stimulation (DBS) and levodopa on gait and cognitive in advanced Parkinson's disease (PD) are not established. Less is known about the effect of stimulation on cognitive function and the capacity to walk while dual tasking [1]. The Gait Profile Score (GPS) and the Mo...

AIM The aim of the study was to describe daily physical activity levels of adolescents and young adults with bilateral spastic cerebral palsy (CP) and to identify factors that help predict these levels. METHOD Daily physical activity was measured using an accelerometer-based activity monitor in 45 young people with bilateral spastic CP (23 males, 2...

Background: Gait disorders are common in individuals with Parkinson's Disease (PD) and the concurrent performance of motor and cognitive tasks can have marked effects on gait. The Gait Profile Score (GPS) and the Movement Analysis Profile (MAP) were developed in order to summarize the data of kinematics and facilitate understanding of the results o...

Normalizing clinical gait analysis data is required to remove variability due to physical characteristics such as leg length and weight. This is particularly important for children where both are associated with age. In most clinical centres conventional normalization (by mass only) is used whereas there is a stronger biomechanical argument for non...

Comparison of normative data between gait analysis services offers the potential to harmonise data collection protocols. This paper presents a method for such a comparison based on an assumption that the root mean square difference from the inter-service mean is a reflection of systematic differences in protocols and that the average standard devia...

This study was a 12-month prospective investigation of changes in the medial gastrocnemius (MG) muscle morphology in children aged 2-5 years with spastic cerebral palsy (CP) who had received no previous intramuscular injections of botulinum neurotoxin type-A (BoNT-A) and were randomised to receive either single or multiple (three) BoNT-A injections...

Soft tissue artifact (STA) has been identified as the most critical source of error in clinical gait analysis. Multiple calibration is a technique to reduce the impact of STA on kinematic data, which involves several static calibrations through the range of motion of the joint of interest. This study investigated how skin markers at the pelvis were...

The aims of this study were to (1) determine whether an instrumented measure will reduce measurement error to less than 5° in children with cerebral palsy (CP), (2) determine agreement and reliability of this instrumented measure in both conscious and anaesthetized participants, and (3) compare the method with previously reported measures. Thirty-f...

Although, several thorax models have been proposed for clinical gait analysis, none has received widespread acceptance nor been subject to any extensive validation work, especially for the marker set to use. The aim of this study was thus to determine the optimal and minimal makers' placement on the thorax for clinical gait analysis. Ten healthy su...

Original Eighty-eight per cent of results were below 20 mm for HAR, 4% for PIG, 85% for sphere fitting techniques (both geometric and algebraic), and 50% for transformational techniques. Corrected Seventy-six per cent of results were below 20 mm for HAR, 18% for PIG, 89% for sphere fitting techniques (both geometric and algebraic), and 55% for tran...

The aim of this study was to investigate whether individualized resistance training improves the physical mobility of young people with cerebral palsy (CP). Forty-eight participants with spastic diplegic CP (26 males, 22 females; mean age 18y 1mo, SD 1y 11mo) classified as level II or III on the Gross Motor Function Classification System were alloc...

Solid ankle-foot orthoses (AFOs) are designed to immobilise the ankle but numerous studies have measured a considerable ankle range of motion (ROM) in AFO users. Measurement of ankle kinematics may be affected by soft-tissue artefact (STA) of the knee marker, deformation of the AFO or tibial movement within the AFO. A new model based on the Convent...

Purpose: This is a study of all children with spastic diplegic cerebral palsy (Gross Motor Classification System levels II and III) who had single event multi-level surgery (SEMLS) at a single tertiary referral hospital between 1995 and 2008 to identify factors predicting improvement in gait quality as quantified by the gait profile score (GPS). 9...

Background: Gait and function may deteriorate with time in patients with spastic diplegia. Single-event multilevel surgery often is performed to either improve gait or prevent deterioration. However it is unclear whether the presumed gait improvements are durable. Questions/purposes: We therefore determined whether (1) single-event multilevel su...

Functional calibration techniques have been proposed as an alternative to regression equations for estimating the position of the hip within the pelvic co-ordinate system for clinical gait analysis. So far validation of such techniques has focussed on healthy adults. This study evaluated a range of techniques based on regression equations or functi...

Two of the most common gait patterns in children with spastic diplegic cerebral palsy (CP) are termed 'crouch gait' and 'jump gait'. While outcomes of surgical interventions designed to improve functional mobility are generally positive, many children displaying these gait patterns show minimal or no improvement post-surgery. A poor response to tre...

The minimally clinically important difference (MCID) is an important concept for interpreting the results of clinical research. This paper proposes a rationale for defining an MCID for the Gait Profile Score (GPS) based on an analysis of the difference in median GPS for children classified at different levels of the Functional Assessment Questionna...

Multilevel orthopaedic surgery may improve gait in Type IV hemiplegia, but it is not known if proximal femoral osteotomy combined with adductor release as part of multilevel surgery in patients with hip dysplasia improves hip development. We asked whether varus derotational osteotomy of the proximal femur, combined with adductor release, influenced...

Three different methods for describing three dimensional joint angles are commonly used in biomechanics. The joint coordinate system and Cardan/Euler angles are conceptually quite different but are known to represent the same underlying mathematics. More recently the globographic method has been suggested as an alternative and this has proved parti...

Locating the position of the hip joint centre (HJC) is an important part of lower limb modeling for gait analysis. Regression equations have been used in the past but a range of functional calibration methods are now available. This study compared the accuracy of HJC localization from two sets of regression equations and five different functional c...

Biomechanical assessments of muscle function are often performed using a generic musculoskeletal model created from anatomical measurements obtained from cadavers. Understanding the validity of using generic models to study movement biomechanics is critical, especially when such models are applied to analyze the walking patterns of persons with imp...

Aim The aim of this article was to compare medial gastrocnemius muscle volume, physiological cross-sectional area (PCSA), muscle length, fascicle length, and pennation angle in children aged 2 to 5 years with spastic cerebral palsy (CP) and in typically developing children. Method Fifteen children with spastic CP (11 males, four females; mean age 4...

Single-event multilevel surgery is considered the standard of care to improve gait and functioning of children with spastic diplegic cerebral palsy. However, the evidence base is limited. This pilot study is the first randomized controlled trial of single-event multilevel surgery, to our knowledge. Nineteen children (twelve boys and seven girls wit...

Equinus is the commonest deformity in cerebral palsy (CP). Many different surgical procedures have been described for the treatment of spastic equinus. In long standing equinus deformities the tibialis anterior muscle becomes elongated which is one reason for muscle weakness. Surgical tendon shortening of the tibialis anterior tendon was therefore...

To investigate the spectrum and relationships between gait patterns and motor function in a population-based cross study of children with unilateral cerebral palsy (CP). Children identified with unilateral CP born in Victoria, Australia, from 1990 to 1992 were eligible to participate. Characteristics were reported using the Winters, Gage, and Hicks...

The purpose of this study was to determine the association between isometric muscle strength of the lower limbs and gait joint kinetics in adolescents and young adults with cerebral palsy (CP). Twenty-five participants (11 males) with bilateral spastic CP, aged 14-22 years (mean: 18.9, sd: 2.0 yr) and Gross Motor Function Classification System (GMF...

This systematic review focused on the common conventional physiotherapy interventions used with children with cerebral palsy (CP), aged 4 to 18 years, and critically appraised the recent evidence of each of these interventions using the Oxford Centre for Evidence-Based Medicine Levels of Evidence. The search strategy yielded 34 articles after inclu...

This study examined inter-rater reliability of the Functional Mobility Scale (FMS) for children with cerebral palsy (CP) and the presence of rater bias. A consecutive sample of 118 children with CP, 2-18 years old (mean 10.3 years, SD 3.6), was recruited from a hospital setting. Children were classified using the gross motor function classification...

Studies which have examined the effects of ankle-foot orthoses (AFOs) on children with cerebral palsy (CP) often report insufficient detail about the participants, devices and testing protocols. The aim of this systematic review was to evaluate the level and quality of detail reported about these factors in order to generate best practice guideline...

The Gait Profile Score (GPS) is a single index measure that summarises the overall deviation of kinematic gait data relative to normative data. The GPS can be decomposed to provide Gait Variable Scores (GVS) of nine key component kinematic gait variables, which are presented as a Movement Analysis Profile (MAP). The purpose of this study was to inv...

The soft-tissue interface between skin-mounted markers and the underlying bones poses a major limitation to accurate, non-invasive measurement of joint kinematics. The aim of this study was twofold: first, to quantify lower limb soft-tissue artifact in young healthy subjects during functional activity; and second, to determine the effect of soft-ti...

The need to share gait analysis data to improve clinical decision support has been recognised since the early 1990s. GaitaBase has been established to provide a web-accessible repository system of gait analysis data to improve the sharing of data across local and international clinical and research community. It is used by several clinical and rese...

This paper describes the calibration process for 3-D free hand ultrasound (3-DUS). The Cambridge calibration technique was determined to produce the most repeatable and accurate results when determining the location of a reference object within a water bath. This note additionally validates 3-DUS as a potential measurement tool for the determinatio...