A functional evaluation of prosthetic foot kinematics during lower-limb amputee gait

Coordination of Lower Limb During Gait in Individuals With Unilateral Transfemoral Amputation

Understanding the lower-limb coordination of individuals with unilateral transfemoral amputation (uTFA) while walking is essential to understand their gait mechanisms. Continuous relative phase (CRP) analysis provides insights into gait coordination patterns of the neuromusculoskeletal system based on movement kinematics. Fourteen individuals with uTFA and their age-matched non-disabled individuals participated in this study. Kinematic data of the lower limbs of the participants were collected during walking. The joint angles, segment angles, and CRP values of the thigh-shank and shank-foot couplings were investigated. The curves among the lower limbs of the participants were compared using a statistical parametric mapping test. Compensatory strategies were found in the lower limbs from coordination patterns. In thigh-shank coupling, although distinct coordination traits in stance and swing phases among the lower limbs were found, the lower limbs in both groups were discovered to remain in a similar coordination pattern during gait. For individuals with uTFA, in shank-foot coupling, intact limbs demonstrated a short period of foot-leading pattern which was significantly different from that of the other limbs during mid-stance to compensate for the weaker force generation by prosthetic limbs. The findings offer normative coordination patterns on the walking of individuals with uTFA, which could benefit prosthetic gait rehabilitation and development.

Differences in Kinematic Changes From Self-Selected to Fast Speed Gait in Asymptomatic Adults With Radiological Signs of Femoro-Acetabular Impingement

Femoro-acetabular impingement (FAI) may present as alterations in the skeletal morphology of the hip. Repercussions of FAI can be witnessed in self-selected speed walking as well as physical exercise such as running or fast speed walking. The aim of this study was to investigate changes in kinematics at different gait speeds in subjects presenting with radiological findings invoking FAI. One hundred thirty asymptomatic adults underwent biplanar X-rays with a calculation of 3D hip parameters: acetabular anteversion, abduction and tilt, vertical center edge angle (VCE), femoral anteversion, neck-shaft angle, acetabular coverage of the femoral head, femoral head diameter and neck length. Parameters were classified according to FAI clinical thresholds. Two groups were created: Control group (63 subjects having up to one subnormal hip parameter in favour of FAI) and Radiographic FAI group (67 subjects having ≥2 subnormal hip parameters that might cause FAI). All subjects underwent 3D gait analysis at self-selected and fast speed, from which kinematic parameters were generated. Arithmetic differences between fast and self-selected speed gait were considered as gait changes. Subjects in the Radiographic FAI group had decreased acetabular tilt (24 vs. 19˚), anteversion (19 vs. 16˚), abduction (55 vs. 53˚), femoral anteversion (18 vs. 14˚) and increased VCE (29 vs. 33˚, all p<0.05), compared to controls. Changes from self-selected to fast speed showed that subjects in the Radiographic FAI group had lower range of motion (ROM) pelvic rotation (7 vs. 4˚) and ROM hip flexion/extension (10 vs. 7˚), reduced hip extension (-4 vs. -2˚) and step length (16 vs. 13 cm; all p<0.05). The Radiographic FAI group had decreased acetabular abduction, anteversion and femoral anteversion in favour of FAI. When adapting from self-selected to fast speed gait, the Radiographic FAI group seemed to limit pelvic rotation and hip flexion/extension resulting in a decrease in step length. These kinematic limitations were previously reported in subjects with symptomatic FAI. Gait analysis could be considered as a functional diagnostic tool to assess FAI along with radiological assessment.

Kinetic Gait Parameters in Unilateral Lower Limb Amputations and Normal Gait in Able-Bodied: Reference Values for Clinical Application

Unilateral lower limb amputations usually present with asymmetric interlimb gait patterns, in the long term leading to secondary physical conditions and carrying the risk of low physical activity and impairment of general health. To assess prosthetic fittings and rehabilitation measures, reference values for asymmetries as well as the most significant gait parameters are required. Kinetic gait data of 865 patients with unilateral lower limb amputations (hip and knee disarticulations, transfemoral, transtibial and foot amputations) and 216 able-bodied participants were quantitatively assessed by instrumented gait analyses. Characteristic spatiotemporal (stance time, walking speed, step length and width) and ground reaction force parameters (weight-acceptance and push-off peak) were contrasted to normal gait. All spatiotemporal and ground reaction force parameters differed significantly from normal gait with the largest differences in transfemoral amputations. These also differed between amputation levels and showed age-dependencies. The stance time and push-off peak difference were identified as the most discriminative parameters with the highest diagnostic specificity and sensitivity. The present results mark the first step to establishing universal reference values for gait parameters by means of which the quality and suitability of a prosthetic fitting and the rehabilitation progress can be assessed, and are generalizable for all adults with unilateral lower limb amputations in terms of level walking.

STEPFORWARD study: a randomised controlled feasibility trial of a self-aligning prosthetic ankle-foot for older patients with vascular-related amputations

OBJECTIVES

To determine the feasibility of conducting a full-scale randomised controlled trial (RCT) of the effectiveness and cost-effectiveness of a self-aligning prosthetic ankle-foot compared with a standard prosthetic ankle-foot.

DESIGN

Multicentre parallel group feasibility RCT.

SETTING

Five prosthetics centres in England recruiting from July 2018 to August 2019.

PARTICIPANTS

Adults aged ≥50 years with a vascular-related or non-traumatic transtibial amputation for 1 year or longer, categorised as having 'limited community mobility' and using a non-self-aligning ankle-foot.

INTERVENTION

Participants were randomised into one of two groups for 12 weeks: self-aligning prosthetic ankle-foot or existing non-self-aligning prosthetic ankle-foot.

OUTCOMES

Feasibility measures: recruitment, consent and retention rates; and completeness of questionnaire and clinical assessment datasets across multiple time points. Feasibility of collecting daily activity data with wearable technology and health resource use data with a bespoke questionnaire.

RESULTS

Fifty-five participants were randomised (61% of the target 90 participants): n=27 self-aligning ankle-foot group, n=28 non-self-aligning ankle-foot group. Fifty-one participants were included in the final analysis (71% of the target number of participants). The consent rate and retention at final follow-up were 86% and 93%, respectively. The average recruitment rate was 1.25 participants/site/month (95% CI 0.39 to 2.1). Completeness of questionnaires ranged from 89%-94%, and clinical assessments were 92%-95%, including the activity monitor data. The average completion rates for the EQ-5D-5L and bespoke resource use questionnaire were 93% and 63%, respectively.

CONCLUSIONS

This feasibility trial recruited and retained participants who were categorised as having 'limited community mobility' following a transtibial amputation. The high retention rate of 93% indicated the trial was acceptable to participants and feasible to deliver as a full-scale RCT. The findings support a future, fully powered evaluation of the effectiveness and cost-effectiveness of a self-aligning prosthetic ankle-foot compared with a standard non-self-aligning version with some adjustments to the trial design and delivery.

TRIAL REGISTRATION NUMBER

ISRCTN15043643.

Influence of spino-pelvic and postural alignment parameters on gait kinematics

INTRODUCTION

Postural alignment is altered with spine deformities that might occur with age. Alteration of spino-pelvic and postural alignment parameters are known to affect daily life activities such as gait. It is still unknown how spino-pelvic and postural alignment parameters are related to gait kinematics.

RESEARCH QUESTION

To assess the relationships between spino-pelvic/postural alignment parameters and gait kinematics in asymptomatic adults.

METHODS

134 asymptomatic subjects (aged 18-59 years) underwent 3D gait analysis, from which kinematics of the pelvis and lower limbs were extracted in the 3 planes. Subjects then underwent full-body biplanar X-rays, from which skeletal 3D reconstructions and spino-pelvic and postural alignment parameters were obtained such as sagittal vertical axis (SVA), center of auditory meatus to hip axis plumbline (CAM-HA), thoracic kyphosis (TK) and radiologic pelvic tilt (rPT). In order to assess the influence of spino-pelvic and postural alignment parameters on gait kinematics a univariate followed by a multivariate analysis were performed.

RESULTS

SVA was related to knee flexion during loading response (β = 0.268); CAM-HA to ROM pelvic obliquity (β = -0.19); rPT to mean pelvic tilt (β = -0.185) and ROM pelvic obliquity (β = -0.297); TK to ROM hip flexion/extension in stance (β = -0.17), mean foot progression in stance (β = -0.329), walking speed (β = -0.19), foot off (β = 0.223) and step length (β = -0.181).

SIGNIFICANCE

This study showed that increasing SVA, CAM-HA, TK and rPT, which is known to occur in adults with spinal deformities, could alter gait kinematics. Increases in these parameters, even in asymptomatic subjects, were related to a retroverted pelvis during gait, a reduced pelvic obliquity and hip flexion/extension mobility, an increased knee flexion during loading response as well as an increase in external foot progression angle. This was associated with a decrease in the walking pace: reduced speed, step length and longer stance phase.

Gait event detection using inertial measurement units in people with transfemoral amputation: a comparative study

In recent years, inertial measurement units (IMUs) have been proposed as an alternative to force platforms and pressure sensors for gait events (i.e., initial and final contacts) detection. While multiple algorithms have been developed, the impact of gait event timing errors on temporal parameters and asymmetry has never been investigated in people with transfemoral amputation walking freely on level ground. In this study, five algorithms were comparatively assessed on gait data of seven people with transfemoral amputation, equipped with three IMUs mounted at the pelvis and both shanks, using pressure insoles for reference. Algorithms' performance was first quantified in terms of gait event detection rate (sensitivity, positive predictive value). Only two algorithms, based on shank mounted IMUs, achieved an acceptable detection rate (positive predictive value > 99%). For these two, accuracy of gait events timings, temporal parameters, and absolute symmetry index of stance-phase duration (SPD-ASI) were assessed. Whereas both algorithms achieved high accuracy for stride duration estimates (median errors: 0%, interquartile ranges < 1.75%), lower accuracy was found for other temporal parameters due to relatively high errors in the detection of final contact events. Furthermore, SPD-ASI derived from IMU-based algorithms proved to be significantly different to that obtained from insoles data. Graphical abstract Gait event detection with IMU in people with transfemoral amputation: initial contact (IC) and final contact (FC) events at the sound (s) and prosthetic (p) side are identified. Five algorithms were implemented using either shank-mounted or pelvis-mounted IMUs. Gait events were used to estimate temporal parameters (stride duration, stance phase duration [SPD], and double support time) and SPD asymmetry.

Modeling and Design of the Automatic Stance Phase Lock (ASPL) Knee Joint Control Mechanism for Paediatric Users With Transfemoral Amputations

The 2-axes Automatic Stance Phase Lock (ASPL) stance control mechanism has been demonstrated to improve adult amputees' mobility but has yet to be developed for the paediatric population. The overall objective for this work was to characterize the ASPL control mechanism with biomechanical modelling and design a 2-axes ASPL prosthetic knee joint suitable for children between the ages of 6 and 12 years. Paediatric anthropometric data and ASPL control mechanism performance characteristics established from adult ASPL knee users were utilized to develop paediatric-appropriate configurations of the ASPL stance control mechanism. Additional predefined design criteria were also included in the detailed knee design. Developed prototypes of the knee joint, Children-ASPL (CASPL) knee, were clinically validated using a single-subject cross-over study design, to assess control mechanism and overall knee functions. Faster walking speed, longer step and stride length with the CASPL knee suggest potential improvements in overall walking performance. The participant also felt confident walking with the CASPL knee and perceived the locking mechanism to be stable. Stemming from the findings here, future design revisions are aimed to improve the performance of the current prototype, including reliability of knee lock disengagement and performance of the swing phase control mechanism.

Self-aligning prosthetic device for older patients with vascular-related amputations: protocol for a randomised feasibility study (the STEPFORWARD study)

INTRODUCTION

The majority of older patients with a transtibial amputation are prescribed a standard (more rigid, not self-aligning) prosthesis. These are mostly suitable for level walking, and cannot adjust to different sloped surfaces. This makes walking more difficult and less energy efficient, possibly leading to longer term disuse. A Cochrane Review concluded that there was insufficient evidence to recommend any individual type of prosthetic ankle-foot mechanism. This trial will establish the feasibility of conducting a large-scale trial to assess the effectiveness and cost-effectiveness of a self-aligning prosthesis for older patients with vascular-related amputations and other health issues compared with a standard prosthesis.

METHODS AND ANALYSIS

This feasibility trial is a pragmatic, parallel group, randomised controlled trial (RCT) comparing standard treatment with a more rigid prosthesis versus a self-aligning prosthesis. The target sample size is 90 patients, who are aged 50 years and over, and have a transtibial amputation, where amputation aetiology is mostly vascular-related or non-traumatic. Feasibility will be measured by consent and retention rates, a plausible future sample size over a 24-month recruitment period and completeness of outcome measures. Qualitative interviews will be carried out with trial participants to explore issues around study processes and acceptability of the intervention. Focus groups with staff at prosthetics centres will explore barriers to successful delivery of the trial. Findings from the qualitative work will be integrated with the feasibility trial outcomes in order to inform the design of a full-scale RCT.

ETHICS AND DISSEMINATION

Ethical approval was granted by Yorkshire and the Humber-Leeds West Research Ethics Committee on 4 May 2018. The findings will be disseminated via peer-reviewed research publications, articles in relevant newsletters, presentations at relevant conferences and the patient advisory group.

TRIAL REGISTRATION NUMBER

ISRCTN15043643.

Ultrasonographic evaluation of the ankle after unilateral traumatic lower limb amputations

BACKGROUND

Unilateral lower limb amputation can alter the tissue morphology leading to increase future risk of degenerative secondary disorders.

METHODS

Thirty-four consecutive male patients with unilateral lower limb amputations of different levels and 34 well matched male controls were included. To explore whether the ankles of traumatic lower limb amputees were undergoing morphological changes, three different tissue types i.e. talar cartilage, plantar fascia and Achilles tendon thicknesses in the intact limb of the lower limb amputee and healthy controls were measured by using ultrasound.

RESULTS

Plantar fascia was found to be thicker (p=0.013) and talar cartilage was thinner (p<0.001) on the intact sides of the patients than those of the controls. Achilles tendon thickness was found to be similar. In patients group, plantar fascia thickness was positively correlated with age (r=0.601, p<0.001), BMI (r=0.454, p=0.007) and durations of amputation (r=0.443, p=0.009) and prosthetic use (r=0.429, p=0.011). Achilles tendon thickness was positively correlated with durations of amputation (r=0.338, p=0.05) and prosthetic use (r=0.468, p=0.005). In controls group, talar cartilage thickness was negatively correlated with age (r=-0.640, p<0.001) and BMI (r=-0.401, p=0.019).

CONCLUSIONS

The talar cartilage seemed to be thinner and the plantar fascia to be thicker on the intact sides of the unilateral limb amputees.

Instantaneous stiffness and hysteresis of dynamic elastic response prosthetic feet

BACKGROUND

Dynamic elastic response prosthetic feet are designed to mimic the functional characteristics of the native foot/ankle joint. Numerous designs of dynamic elastic response feet exist which make the prescription process difficult, especially because of the lack of empirical evidence describing the objective performance characteristics of the feet.

OBJECTIVES

To quantify the mechanical properties of available dynamic elastic response prosthetic feet, specifically the stiffness and hysteresis.

STUDY DESIGN

Mechanical testing of dynamic elastic response prosthetic feet.

METHODS

Static Proof Testing in accordance with ISO 10328 was conducted on seven dynamic elastic response prosthetic feet. Load-displacement data were used to calculate the instantaneous stiffness in both the heel and forefoot regions, as well as hysteresis associated with each foot.

RESULTS

Heel stiffness was greater than forefoot stiffness for all feet. The heel of the glass composite prosthetic foot was stiffer than the carbon fiber feet and it exhibited less hysteresis. Two different carbon fiber feet had the stiffest forefoot regions.

CONCLUSION

Mechanical testing is a reproducible method that can be used to provide objective evidence about dynamic elastic response prosthetic foot performance and aid in the prescription process. Clinical relevance The quantitative stiffness and hysteresis data from this study can be used by prosthetists to aid the prescription process and make it more objective.

Roussouly's sagittal spino-pelvic morphotypes as determinants of gait in asymptomatic adult subjects

Sagittal alignment is known to greatly vary between asymptomatic adult subjects; however, there are no studies on the possible effect of these differences on gait. The aim of this study is to investigate whether asymptomatic adults with different Roussouly sagittal alignment morphotypes walk differently. Ninety-one asymptomatic young adults (46M & 45W), aged 21.6±2.2years underwent 3D gait analysis and full body biplanar X-rays with three-dimensional (3D) reconstructions of their spines and pelvises and generation of sagittal alignment parameters. Subjects were divided according to Roussouly's sagittal alignment classification. Sagittal alignment and kinematic parameters were compared between Roussouly types. 17 subjects were classified as type 2, 47 as type 3, 26 as type 4 but only 1 as type 1. Type 2 subjects had significantly more mean pelvic retroversion (less mean pelvic tilt) during gait compared to type 3 and 4 subjects (type 2: 8.2°; type 3:11.2°, type 4: 11.3°) and significantly larger ROM pelvic obliquity compared to type 4 subjects (type 2: 11.0°; type 4: 9.1°). Type 2 subjects also had significantly larger maximal hip extension during stance compared to subjects of types 3 and 4 (type 2: -11.9°; type 3: -8.8°; type 4: -7.9°) and a larger ROM of ankle plantar/dorsiflexion compared to type 4 subjects (type 2: 31.1°; type 4: 27.9°). Subjects with type 2 sagittal alignment were shown to have a gait pattern involving both increased hip extension and pelvic retroversion which could predispose to posterior femoroacetabular impingement and consequently osteoarthritis.

A prosthesis-specific multi-link segment model of lower-limb amputee sprinting

Lower-limb amputees commonly utilize non-articulating energy storage and return (ESAR) prostheses for high impact activities such as sprinting. Despite these prostheses lacking an articulating ankle joint, amputee gait analysis conventionally features a two-link segment model of the prosthetic foot. This paper investigated the effects of the selected link segment model׳s marker-set and geometry on a unilateral amputee sprinter׳s calculated lower-limb kinematics, kinetics and energetics. A total of five lower-limb models of the Ottobock^® 1E90 Sprinter were developed, including two conventional shank-foot models that each used a different version of the Plug-in-Gait (PiG) marker-set to test the effect of prosthesis ankle marker location. Two Hybrid prosthesis-specific models were then developed, also using the PiG marker-sets, with the anatomical shank and foot replaced by prosthesis-specific geometry separated into two segments. Finally, a Multi-link segment (MLS) model was developed, consisting of six segments for the prosthesis as defined by a custom marker-set. All full-body musculoskeletal models were tested using four trials of experimental marker trajectories within OpenSim 3.2 (Stanford, California, USA) to find the affected and unaffected hip, knee and ankle kinematics, kinetics and energetics. The geometry of the selected lower-limb prosthesis model was found to significantly affect all variables on the affected leg (p < 0.05), and the marker-set also significantly affected all variables on the affected leg, and none of the unaffected leg variables. The results indicate that the omission of prosthesis-specific spatial, inertial and elastic properties from full-body models significantly affects the calculated amputee gait characteristics, and we therefore recommend the implementation of a MLS model.

Comparison of gait after Syme and transtibial amputation in children: factors that may play a role in function

BACKGROUND

Preservation of maximal limb length during amputation is often recommended to maximize the efficiency and symmetry of gait. The goals of this study were to determine (1) whether there are gait differences between children with a Syme (or Boyd) amputation and those with a transtibial-level amputation, and (2) whether the type of prosthetic foot affects gait and PODCI (Pediatric Outcomes Data Collection Instrument) outcomes.

METHODS

Sixty-four patients (age range, 4.7 to 19.2 years) with unilateral below-the-knee prosthesis use (forty-one in the Syme group and twenty-three in the transtibial group) underwent gait analysis and review of data for the involved limb. The twelve prosthetic foot types were categorized as designed for a high, medium, or low activity level (e.g., Flex foot, dynamic response foot, or SACH). Statistical analyses were conducted.

RESULTS

Kinematic differences of <4° in total prosthetic ankle motion and 8° in external hip rotation were seen between the Syme and transtibial groups. Ankle power was greater in the transtibial group, whereas the Syme group had greater coronal-plane hip power (p < 0.05). Prosthetic ankle motion was significantly greater in the high compared with the medium and low-performance feet. However, the PODCI happiness score was higher in patients with low compared with medium-performance feet (p < 0.05).

CONCLUSIONS

Small differences in prosthetic ankle motion and power were found between children with Syme and transtibial amputations. Ankle motion was greater in patients using high-performance feet (9% of the total cohort) compared with medium-performance (59%) and low-performance (31%) feet. Despite the increased ankle motion achieved with high-performance dynamic feet, this advantage was not reflected in peak power of the prosthetic ankle or the PODCI sports/physical functioning subscale.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Gait biomechanics of individuals with transtibial amputation: effect of suspension system

Prosthetic suspension system is an important component of lower limb prostheses. Suspension efficiency can be best evaluated during one of the vital activities of daily living, i.e. walking. A new magnetic prosthetic suspension system has been developed, but its effects on gait biomechanics have not been studied. This study aimed to explore the effect of suspension type on kinetic and kinematic gait parameters during level walking with the new suspension system as well as two other commonly used systems (the Seal-In and pin/lock). Thirteen persons with transtibial amputation participated in this study. A Vicon motion system (six cameras, two force platforms) was utilized to obtain gait kinetic and kinematic variables, as well as pistoning within the prosthetic socket. The gait deviation index was also calculated based on the kinematic data. The findings indicated significant difference in the pistoning values among the three suspension systems. The Seal-In system resulted in the least pistoning compared with the other two systems. Several kinetic and kinematic variables were also affected by the suspension type. The ground reaction force data showed that lower load was applied to the limb joints with the magnetic suspension system compared with the pin/lock suspension. The gait deviation index showed significant deviation from the normal with all the systems, but the systems did not differ significantly. Main significant effects of the suspension type were seen in the GRF (vertical and fore-aft), knee and ankle angles. The new magnetic suspension system showed comparable effects in the remaining kinetic and kinematic gait parameters to the other studied systems. This study may have implications on the selection of suspension systems for transtibial prostheses.

Trial Registration

Iranian Registry of Clinical Trials IRCT2013061813706N1.

Keep moving forward: a new energy returning prosthetic device with low installation height after Syme or Pirogoff amputation

BACKGROUND

The incidence of foot amputations increased in the Netherlands to 3.3/100,000 people up to 1994. Despite these numbers, only a few basic prosthetic and orthotic devices are available, and all lack functionality to restore ankle and foot mobility.

OBJECTIVES

The aim of this explorative study was to design and test a unique prosthesis for Syme or Pirogoff amputees with the necessary low installation height but restoring ankle and foot mobility.

STUDY DESIGN

A case study was performed.

METHODS

The new prosthesis was designed and numerically analyzed on aspects concerning strength and deformation. A prototype was tested in a case study to assess the biomechanical behavior of the new foot. As a reference, six Syme/Pirogoff amputees were measured. Additionally, all volunteers filled out a questionnaire to evaluate their prosthetic feet.

RESULTS

The self-selected and maximum walking speed of the case subject at 0° and 5° slopes was higher using the new foot (0.36 m/s and 0.53 m/s, respectively) comparing to the Low Rider (Otto Bock HealthCare) (0.31 m/s and 0.31 m/s, respectively). Using the new foot, a more symmetrical walking pattern was achieved.

CONCLUSION

The case study shows that this new prosthetic foot could be an improvement compared to existing prosthetic feet.

CLINICAL RELEVANCE

Foot amputees with low available installation height still experience daily the inconvenience of missing ankle and foot mobility. Their low velocity and cosmetically poor walking pattern influence on their sound leg and overall walking functionality. A more functional prosthesis would have a great impact on their daily activities.

The KneeKG system: a review of the literature

PURPOSE

Accurately quantifying knee joint motion is not simple. Skin movement over the medial and lateral femoral condyles is the greatest obstacle to obtaining accurate movement data non-invasively. The KneeKG™ system was developed with the objective of providing high reliability movement analysis. The goal of this manuscript is to review the technical details, clinical evidence, and potential applications of this system for evaluation of rotational knee laxity.

METHODS

A comprehensive review of the MEDLINE database was carried out to identify all clinical and biomechanical studies related to KneeKG™ system.

RESULTS

The KneeKG™ system non-invasively quantifies knee abduction/adduction, axial rotation, and relative translation of the tibia and femur. The accuracy and reproducibility of the system have been assessed. The average accuracy of the acquisition is 0.4° for abduction/adduction, 2.3° for axial rotation, 2.4 mm for anteroposterior translation, and 1.1 mm for axial translation. This clinical tool enables an accurate and objective assessment of the tri-planar function of the knee joint. The measured biomechanical parameters are sensitive to changes in gait due to knee osteoarthritis and ACL deficiency.

CONCLUSION

The KneeKG™ system provides reliable movement analysis. This system has the potential to improve understanding the biomechanical consequences of trauma or degenerative changes of the knee as well as more accurately quantify rotational laxity as detected by a positive pivot-shift test.

Finite element modelling of an energy–storing prosthetic foot during the stance phase of transtibial amputee gait

Energy-storing prosthetic feet are designed to store energy during mid-stance motion and to recover it during late-stance motion. Gait analysis is the most commonly used method to characterize prosthetic foot behaviour during walking. In using this method, however, the foot is generally modelled as a rigid body. Therefore, it does not take into account the ability of the foot to deform. However, the way this deformation occurs is a key parameter of various foot properties under gait conditions. The purpose of this study is to combine finite element modelling and gait analysis in order to calculate the strain, stress and energy stored in the foot along the stance phase for self-selected and fast walking speeds. A finite element model, validated using mechanical testing, is used with boundary conditions collected experimentally from the gait analysis of a single transtibial amputee. The stress, strain and energy stored in the foot are assessed throughout the stance phase for two walking speed conditions: a self-selected walking speed (SSWS), and a fast walking speed (FWS). The first maximum in the strain energy occurs during heel loading and reaches 3 J for SSWS and 7 J for FWS at the end of the first double support phase. The second maximum appears at the end of the single support phase, reaching 15 J for SSWS and 18 J for FWS. Finite element modelling combined with gait analysis allows the calculation of parameters that are not obtainable using gait analysis alone. This modelling can be used in the process of prosthetic feet design to assess the behaviour of a prosthetic foot under specific gait conditions.

Biomechanical models in the study of lower limb amputee kinematics: a review

BACKGROUND

Optoelectronic motion capture may provide a platform for the development of objective biomechanical outcome measures applicable to the young, active individual with lower limb loss. In order to create valid and robust tools, the modelling strategy applied must adequately represent both natural and prosthetic segments and joints.

OBJECTIVES

To explore existing usage of optoelectronic motion capture and modelling strategies for the analysis of amputee function.

STUDY DESIGN

Literature review.

METHODS

Systematic search of Medline (OVID) and keyword search of the Journal of Prosthetics and Orthotics.

RESULTS

Over 60% (n = 32) of the 51 studies extracted adopted a conventional three degree-of-freedom modelling approach. Linear segment representation (15%) and six degree-of-freedom techniques (19%) were employed in the remaining papers. Prosthetic modelling strategies were poorly reported. Landmarks were estimated from corresponding positions on the contralateral intact limb, mechanical joint centres and regression equations. No model defined the residuum and socket independently.

CONCLUSIONS

In the absence of a definitive solution, it is essential that the limitations of any model are understood in the development and establishment of reliable outcome measures for this population using motion capture technology. Poor reporting and a lack of consistency make comparison of results between studies and institutions impractical.

CLINICAL RELEVANCE

Standard modelling techniques may not consistently represent the body and prosthesis adequately to produce valid results for the analysis of function of persons with lower limb loss. Variation in modelling techniques limits the utility of findings reported in the literature. Development and application of a uniform, robust modelling strategy would benefit research and clinical practice.

Biomechanics and physiological parameters during gait in lower-limb amputees: a systematic review

OBJECTIVE

The purpose of this systematic review was to identify which biomechanical and physiological parameters are the most relevant, commonly used, able to discriminate and/or have specific clinical relevance for the gait analysis of lower-limb amputees (LLA).

METHODS

We performed an electronic search via the PubMed, EMBASE and ISI Web of Knowledge databases from 1979 to May 2009. Two independent reviewers assessed the title and abstract of each identified study. The quality assessment of the full text was undertaken using a 13-item checklist divided into three levels: A, B, and C.

RESULTS

The literature search identified 584 abstracts to be considered. After applying the inclusion criteria, we reviewed the full text of a total of 89 articles. The mean article quality was 8±2. No A-level article was found; the primary reason was a negative score in blinded outcome assessment. Sixty-six articles (74%) corresponded to a B-level, and two articles (2%) corresponded to a C-level. Twenty-one articles (24%) did not acquire enough points to be assigned to any level. In this study, we present and discuss the most commonly used and most relevant 32 parameters. Many of the parameters found were not reported in enough studies or in enough detail to allow a useful evaluation.

CONCLUSION

This systematic review can help researchers compare, choose and develop the most appropriate gait evaluation protocol for their field of study, based on the articles with best scores on the criteria list and the relevance of specific biomechanical and physiological parameters.

Motion-analysis studies of transtibial prosthesis users: a systematic review

BACKGROUND

Three-dimensional motion analysis has been used since the beginning of the 1980s to evaluate many aspects of physical function of transtibial amputees. Despite its common use for clinical research, there is large variability in methods of capturing three-dimensional data, description of these methods, reporting of joint kinematics and interpretation of research findings.

OBJECTIVES

The aim of the following review is to critically examine the specific methodologies used by researchers when collecting three-dimensional kinematic data on transtibial amputees and to provide an overview of the methods used.

STUDY DESIGN

Systematic review.

METHODS

A systematic review of the literature between January 1984 and June 2009 was conducted. A total of 68 papers were identified for review based on the following criteria: experimental research design, collection of three-dimensional kinematic data of lower-extremity joints, and inclusion of transtibial amputees as experimental subjects.

RESULTS

A number of methodological shortcomings were identified in the papers reviewed.

CONCLUSIONS

The authors recommend that future studies more appropriately address the product name and number of prosthetic components used; how the position of reflective markers on the prosthesis is defined; presentation of data from both sound and affected sides; and definition of the neutral position of the ankle when reporting kinematic data. Where possible, the authors recommend use of a control group.

CLINICAL RELEVANCE

This paper has identified numerous sources of discrepancy and potential error in kinematic data collected on trans-tibial amputees. Clinicians and researchers should make themselves aware of these issues when collecting and interpreting gait data.

Evaluation of force plate-less estimation of the trajectory of the centre of pressure during gait. Comparison of two anthropometric models

The estimation of the trajectory of the centre of pressure during gait is possible without using force plate by modelling the whole body as a multi-segment chain. The kinematics and inertial parameters of each segment are necessary to determine the ground reaction forces and moments. The position of the centre of pressure can then be calculated at each frame of time. The objective of the study was to evaluate the accuracy of the estimation of the position of the centre of pressure during gait obtained without force plate data. Segment inertial parameters were determined using a proportional model and a geometric model. The modelling and calculations were computed for six volunteers and the estimated centres of pressure were compared to the centre of pressure measured using force plates considered as the gold standard. The estimation was better using the geometric model with an accuracy of 33 mm (4.1% of the peak-to-peak amplitude) on the longitudinal axis and 14.2 mm (12.9% of the peak-to-peak amplitude) on the lateral axis.

Gait analysis in children and uncertainty assessment for Davis protocol and Gillette Gait Index

The protocol of Davis is widely used in children's gait analysis, especially in cerebral palsy studies and its repeatability was evaluated primarily for adults. The aim of this research was to evaluate the uncertainty and repeatability of this protocol for children. 56 asymptomatic children aged 5-15 years performed the gait exam. Kinematics parameters and Gillette Gait Index (GGI) were calculated. 17 subjects performed the exam twice with markers replacement. Uncertainties on gait parameters were evaluated using repeatability study and Monte Carlo simulations. Uncertainty (2SD of test-retest differences) obtained on angles calculated by the protocol varied between +/-2 degrees and +/-3 degrees (for pelvis and hip in sagittal and frontal planes) and +/-14 degrees (for mean hip rotation). Uncertainty on GGI was +/-12 for healthy subjects. Monte Carlo simulations on 30 cerebral palsy children showed that the error on GGI could reach +/-100 and was correlated to GGI value (R2=0.92): 2SD=24+0.09xGGI.

Optimal mechanical design of anatomical post-systems for endodontic restoration

This paper analyses the mechanical behaviour of a new reinforced anatomical post-systems (RAPS) for endodontic restoration. The composite restorative material (CRM) completely fills the root canal (as do the commonly used cast metal posts) and multiple prefabricated composite posts (PCPs) are employed as reinforcements. Numerical simulations based on 3D linearly elastic finite element models under parafunctional loads were performed in order to investigate the influence of the stiffness of the CRM and of the number of PCPs. Periodontal ligament effects were taken into account using a discretised anisotropic nonlinearly elastic spring system, and the full discrete model was validated by comparing the resulting stress fields with those obtained with conventional restorations (cast gold-alloy post, homogeneous anatomical post and cemented single PCP) and with the natural tooth. Analysis of the results shows that stresses at the cervical/middle region decrease as CRM stiffness increases and, for large and irregular root cavities that apical stress peaks disappear when multiple PCPs are used. Accordingly, from a mechanical point of view, an optimal RAPS will use multiple PCPs when CRM stiffness is equal to or at most twice that of the dentin. This restorative solution minimises stress differences with respect to the natural tooth, mechanical inhomogeneities, stress concentrations on healthy tissues, volumes subject to shrinkage phenomena, fatigue effects and risks of both root fracture and adhesive/cohesive interfacial failure.

Correlation of residual limb length and gait parameters in amputees

There is a lack of objective data on acceptable transection levels for transfemoral amputation. We retrospectively correlated the residual limb length of 13 young, athletic transfemoral and knee disarticulation amputees with temporal-spatial, kinematic, and kinetic outcomes after gait analysis. It was hypothesised that shorter residual limb lengths would correlate with greater gait deviations. Patients' residual femoral lengths ranged from 57% to 100% of their intact femoral length. With the exception of one patient, pelvic tilt excursion was inversely related to residual limb length. Limb length did not significantly correlate with any other temporal-spatial, kinematic, or kinetic parameter investigated. Consequently, these results suggest that if the femur is at least 57% of the length of the contralateral femur, length does not dramatically alter gait. This implies that surgeons may have more flexibility to amputate at a higher level to preserve soft tissue quality and improve prosthetic fitting without sacrificing gait function.

Functional gait analysis of trans-femoral amputees using two different single-axis prosthetic knees with hydraulic swing-phase control: Kinematic and kinetic comparison of two prosthetic knees

This paper reports a comparison of the gait patterns of trans-femoral amputees using a single-axis prosthetic knee that coordinates ankle and knee flexions (Proteor's Hydracadence system) with the gait patterns of patients using other knee joints without a knee-ankle link and the gait patterns of individuals with normal gait. The two patient groups were composed of 11 male trans-femoral amputees: six patients had the Hydracadence joint (Group 1) and five patients had other prosthetic knees (Group 2). The reference group was made up of 23 normal volunteers (Group 3). In this work, trunk, hip, knee, and ankle 3-D motion was assessed using the VICON system. Kinetic data were collected by two AMTI force plates, and the knee moment was calculated via the 3-D equilibrium equations. An original questionnaire was used to assess the participants' activity level and clinical background. The results reveal that, during stance, all knee types guaranteed security. After heel strike, the plantar flexion of the ankle enabled by the Hydracadence prosthesis seems to increase stability. During swing phase, hip and knee sagittal motion was nearly the same in both Group 1 and Group 2. By contrast, hallux and sole vertical positions were significantly higher in Group 1 than in Group 2; thus, it seems the link between the ankle joint and the knee joint makes foot clearance easier. No alteration of the lateral bending of the trunk was observed. The protocol proposed in this paper allows a functional comparison between prosthetic components by combining clinical data with objective 3-D kinematic and kinetic information. It might help to determine which prosthetic knees are best for a specific patient.

Three-dimensional motions of trunk and pelvis during transfemoral amputee gait

OBJECTIVES

To identify characteristics of upper-body kinematics and torque transmission to the ground during locomotion in a group of patients with transfemoral amputation as compared with a group of asymptomatic subjects; and to investigate the influence of walking velocity and residual limb length on several characteristics of upper-body motion.

DESIGN

Three-dimensional gait analysis with an optoelectronic device.

SETTING

Gait laboratory.

PARTICIPANTS

Twenty-seven patients with transfemoral amputation and a control group of 33 nondisabled subjects.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Three-dimensional kinematics of the pelvis and the thorax and ground reaction force for amputees and control subjects.

RESULTS

For subjects with transfemoral amputation, it was observed that upper-body angular ranges of motion (ROMs) increased globally as walking velocity decreased. For these subjects, specific patterns of pelvic rotation and torque transmission by the lower limbs around the vertical axis were found. The counter-rotation between the pelvic and scapular girdles was reduced. This reduction proved to be linked with the decrease of walking velocity. Walking velocity also affected all the parameters describing the motion of upper body. Pelvic ROM increased with the length of the limb decreasing.

CONCLUSIONS

The huge differences found between subjects with and without amputation suggest that the motion of the upper body must be considered to enhance gait.

Comparing three attachment systems used to determine knee kinematics during gait

This work compared three attachment systems (AS) designed to minimize soft tissue artefacts in gait analysis measurements. The systems' displacement for different knee flexion angles and after 50 gait cycles was investigated using an EOS low dose biplanar X-ray system. Eighteen subjects (six per AS) were equipped with one AS and placed in five positions. Frontal and profile views were taken for each position. The bones' 3D model and the AS's position were obtained from stereoradiographic reconstructions. The AS's relative position to the underlying bone were computed and interpreted in the anatomical coordinate systems (CS). The AS appeared to be stable in the frontal and sagittal plane (under 1.5 degrees average displacement around the underlying bones) but unstable in the axial plane (over 6 degrees average displacement). The average translation along the femoral and tibial diaphysis was 4.5mm and 2.7 mm, respectively. Femoral system B translated significantly less along the diaphysis than the other AS. Concerning the axial rotation, system C appeared to present the most important displacement but there was no statistically significant difference. Systems A and B's rotation in the transverse plane correlated to the knee flexion angle. For the tibia, system B was more stable than systems A and C (p=0.04). On the whole, system B appeared to be the most stable system. This study highlights the fact that no system can limit displacement in the transverse plane.