Christopher Nester

Effect of foot orthoses on the kinematics and kinetics of normal walking gait

Despite their wide clinical application and success, our understanding of the biomechanical effects of foot orthoses is relatively limited. The aim of this study was to assess the effect of medially wedged and laterally wedged foot orthoses on the kinematics and joint moments of the rearfoot complex, knee, hip and pelvis and the ground reaction forces. The principal effect of the foot orthoses was on the rearfoot complex, where significant changes in joint rotations and moments were observed. Medially wedged orthoses decreased rearfoot pronation and increased the laterally directed ground reaction force during the contact phase, suggesting reduced shock attenuation. The laterally wedged orthoses increased rearfoot pronation and decreased the laterally directed ground reaction force during the contact phase, suggesting increased shock attenuation. The effects of the orthoses on knee, hip and pelvis kinematics were generally minimal. In view of the minimal effect the orthoses had on joints proximal to the foot, it is suggested that the orthoses may have additional effects on the passive and active soft tissues of the lower limb and it is these changes that result in the documented clinical success.

Sprained Ankle Physiotherapy Based Mechanism Synthesis and Stiffness Analysis of a Robotic Rehabilitation Device

Rehabilitation robotics is a growing field where the study of human movement is one of the key topics. Mechanisms development in terms of analysis and synthesis in the field is relatively new, particularly in the case of parallel robotic mechanisms. This paper presents the background and details of current research into the use of parallel robotic mechanisms for rehabilitation of sprained ankles, and proposes a new device based on a parallel mechanism with a central strut.The paper investigates a new technique in motion analysis of ankle movement which is presented in an orientation image space and in that of a rehabilitation therapy, presents an approach of mechanism synthesis based on this analysis, and develops several parallel mechanisms with a central strut for ankle rehabilitation. This is then related to the analysis of the stiffness effect of the central strut in the platform-type mechanism and the stiffness matrix is decomposed with the part resulting from the central strut which supports ankle rehabilitation.In presenting this new research, the paper relates the study of mechanisms to that of rehabilitation robotics and presents a strong case in the new application of parallel robotic mechanisms.

A review of observational gait assessment in clinical practice

For physical therapists observational gait assessment is preferable to instrumented gait assessment in the clinical setting. Existing observational gait assessment tools used in clinical practice were reviewed in terms of their validity, repeatability, sensitivity, and specificity. Most gait assessment tools lacked information concerning their validity or repeatability. In addition, most gait assessment tools had not had their sensitivity and specificity adequately evaluated. Current approaches to the development and use of observational gait assessment tools have been characterised by a top down approach, designing what is useful without any understanding of the appropriateness of a tools content, construction, and so forth. We would advocate a more structured approach, by assessing gait using the gold standard of instrumented gait analysis and designing an observational gait assessment tool based on the data.

The status of gait assessment among physiotherapists in the United Kingdom

OBJECTIVES To evaluate how physiotherapists are trained in and use clinically orientated gait assessment tools and instrumented gait analysis, and to identify if a need exists for a standardized methodology. DESIGN Survey. SETTING UK National Health Service. PARTICIPANTS Physiotherapists working with a variety of patient groups in 210 randomly selected Health Care Trusts. INTERVENTIONS Not applicable. MAIN OUTCOME MEASURES Amount of gait assessment training, frequency of gait laboratory use, types and frequency of standardized gait assessment tools used, and expressed need for a gait assessment tool in clinical practice. RESULTS A total of 1826 (43.5%) physiotherapists responded. Management of abnormal gait constituted a major aspect of physiotherapy practice; yet, there was no systematic use of standardized gait assessment tools. Gait video images were typically collected and analyzed without the use of standardized protocols. Only 23.1% of all respondents had a patient assessed in a gait laboratory. Clinicians indicated that they need training in gait assessment (66.4%) and desire guidance at a national level. Exactly 91.8% of physiotherapists requested a new gait assessment tool that can be used easily and quickly within a busy schedule without compromising reliability and validity. CONCLUSIONS Gait assessment plays a pivotal role for physiotherapists managing gait problems. The challenge for developers of gait assessment tools is to find a balance between the practicalities of use and scientific merit.

Effect of errors in the identification of anatomical landmarks on the accuracy of Q angle values

OBJECTIVE To determine the effect of error in the location of the anterior superior iliac spine, and the centres of the patella and tibial tuberosity, on the measured value of the quadriceps angle. BACKGROUND The quadriceps angle is said to be relevant in the etiology and management of patello-femoral pain. However, the issues around measurement accuracy have not been reported. METHODS Errors between 1 and 5 mm were introduced to the medial/lateral and vertical co-ordinate data describing the position of the anterior superior iliac spine, the centre of the patella and the centre of the tibial tuberosity, and the effect on the quadriceps angle determined. RESULTS Errors between 1 and 5 mm in the medial/lateral location of the centre of the patella produced changes in the quadriceps angle between 1.13 degrees and 5.53 degrees. Errors between 1 and 5 mm in the medial/lateral location of the tibial tuberosity produced changes in the quadriceps angle between 1.02 degrees and 5.18 degrees. CONCLUSIONS The quadriceps angle is highly sensitive to error in the definition of the centre of the patella and tibial tuberosity. As an approximation, these centres need to be defined with an accuracy of less than 2 mm if the error in the quadriceps angle is to remain below 5 degrees. RELEVANCE Until a clinical technique for measuring the quadriceps angle with a high level of accuracy is developed, the clinical use of the quadriceps angle is questionable.

The problem with measuring patient perceptions of outcome with existing outcome measures in foot and ankle surgery

Quality outcome measures are the cornerstone of clinical research. A review of outcome measures used in foot and ankle surgery research reveals that the issues of validity, reliability and responsiveness of outcome measures have not been addressed. Most reports in the literature have attempted to evaluate patient perceptions of outcome following foot surgery. Underlying the many difficulties with these outcome measures is a lack of understanding of what patients perceive to be important in terms of outcome. Consequently none of the existing outcome measures can claim to be valid measures of patient perceptions of outcome, as there has been no research uncovering these perceptions. In addition, measures of general health status and quality of life in relation to outcome of foot and ankle surgery have been largely ignored to date.

A systematic review and meta-analysis of the effect of an ankle-foot orthosis on gait biomechanics after stroke:

Objective: To systematically review the evidence on the effects of an ankle-foot orthosis on gait biomechanics after stroke Data sources: The following databases were searched; AMED, CINHAL, Cochrane Library (Stroke section), Medline, PubMed, Science Direct and Scopus. Previous reviews, reference lists and citation tracking of the selected articles were screened and the authors of selected trials contacted for any further unpublished data. Review methods: Controlled trials of an ankle-foot orthosis on gait biomechanics in stroke survivors were identified. A modified PEDro score evaluated trial quality; those scoring 4/8 or more were selected. Information on the trial design, population, intervention, outcomes, and mean and standard deviation values for the treatment and control groups were extracted. Continuous outcomes were pooled according to their mean difference and 95% confidence intervals in a fixed-effect model. Results: Twenty trials involving 314 participants were selected. An ankle-foot orthosis had a positive effect on ankle kinematics (P < 0.00001–0.0002); knee kinematics in stance phase (P < 0.0001–0.01); kinetics (P = 0.0001) and energy cost (P = 0.004), but not on knee kinematics in swing phase (P = 0.84), hip kinematics (P < 0.18–0.89) or energy expenditure (P = 0.43). There were insufficient data for pooled analysis of individual joint moments, muscle activity or spasticity. All trials, except one, evaluated immediate effects only. Conclusions: An ankle-foot orthosis can improve the ankle and knee kinematics, kinetics and energy cost of walking in stroke survivors.

Functional units of the human foot

Functional units in the human foot provide a meaningful basis for subdivisions of the entire foot during gait analysis as well as justified simplifications of foot models. The present study aimed to identify such functional units during walking and slow running. An invasive method based upon reflective marker arrays mounted on intracortical pins was used to register motion of seven foot bones. Six healthy subjects were assessed during walking and four of them during slow running. Angle-angle diagrams of corresponding planar bone rotations were plotted against each other and used to establish functional units. Individual functional units were accepted when the joints rotated temporally in phase and either (i) in the same direction, (ii) in the opposite direction, or (iii) when one of the two joints showed no rotation. A functional unit was generalized if all available angle-angle diagrams showed a consistent pattern. A medial array from the navicular to the first metatarsal was found to perform as a functional unit with parts rotating in the same direction and larger rotations occurring proximally. A rigid functional unit comprised the navicular and cuboid. No other functional units were identified. It was concluded that the talus, navicular, and medial cuneiform should neither be regarded as one rigid unit nor as one segment during gait analysis. The first and fifth metatarsals should also be considered separately. It was further concluded that a marker setup for gait analysis should consist of the following four segments: calcaneus, navicular-cuboid, medial cuneiform-first metatarsal, fifth metatarsal.

A comparison of the biomechanical effects of valgus knee braces and lateral wedged insoles in patients with knee osteoarthritis

Increases in the external knee adduction moment (EKAM) have been associated with increased mechanical load at the knee and progression of knee osteoarthritis. Valgus knee braces and lateral wedged insoles are common approaches to reducing this loading; however no study has directly compared the biomechanical and clinical effects of these two treatments in patients with medial tibiofemoral osteoarthritis. A cross-over randomised design was used where each intervention was worn by 28 patients for a two week period. Pre- and post-intervention gait kinematic/kinetic data and clinical outcomes were collected to evaluate the biomechanical and clinical effects on the knee joint. The valgus knee brace and the lateral wedged insole significantly increased walking speed, reduced the early stance EKAM by 7% and 12%, and the knee adduction angular impulse by 8.6 and 16.1% respectively. The lateral wedged insole significantly reduced the early stance EKAM compared to the valgus knee brace (p=0.001). The valgus knee brace significantly reduced the knee varus angle compared to the baseline and lateral wedged insole. Improvements in pain and function subscales were comparable for the valgus knee brace and lateral wedged insole. There were no significant differences between the two treatments in any of the clinical outcomes; however the lateral wedged insoles demonstrated greater levels of acceptance by patients. This is the first study to biomechanically compare these two treatments, and demonstrates that given the potential role of knee loading in osteoarthritis progression, that both treatments reduce this but lateral wedge insoles appear to have a greater effect.

Ultrasound evaluation of foot muscles and plantar fascia in pes planus

BACKGROUND Multiple intrinsic and extrinsic soft tissue structures that apply forces and support the medial longitudinal arch have been implicated in pes planus. These structures have common functions but their interaction in pes planus is not fully understood. The aim of this study was to compare the cross-sectional area (CSA) and thickness of the intrinsic and extrinsic foot muscles and plantar fascia thickness between normal and pes planus feet. METHODS Forty-nine adults with a normal foot posture and 49 individuals with pes planus feet were recruited from a university population. Images of the flexor digitorum longus (FDL), flexor hallucis longus (FHL), peroneus longus and brevis (PER), flexor hallucis brevis (FHB), flexor digitorum brevis (FDB) and abductor hallucis (AbH) muscles and the plantar fascia were obtained using a Venue 40 ultrasound system with a 5-13 MHz transducer. RESULTS The CSA and thickness of AbH, FHB and PER muscles were significantly smaller (AbH -12.8% and -6.8%, FHB -8.9% and -7.6%, PER -14.7% and -10%), whilst FDL (28.3% and 15.2%) and FHL (24% and 9.8%) were significantly larger in the pes planus group. The middle (-10.6%) and anterior (-21.7%) portions of the plantar fascia were thinner in pes planus group. CONCLUSION Greater CSA and thickness of the extrinsic muscles might reflect compensatory activity to support the MLA if the intrinsic foot muscle function has been compromised by altered foot structure. A thinner plantar fascia suggests reduced load bearing, and regional variations in structure and function in feet with pes planus.