[Significance of static prosthesis alignment for standing and walking of patients with lower limb amputation]

The significance of frontal plane static alignment in anticipating dynamic knee moment among transtibial prosthesis users: A cross-sectional study

BACKGROUND

In the process of transtibial prosthetic fitting, alignment is the process of positioning the prosthetic foot relative to the residual limb. Changes in frontal plane alignment can impact knee moments during walking, which can either cause or, when aligned properly, prevent injuries. However, clinical evaluation of dynamic knee moments is challenging, limiting prosthetists' insights into dynamic joint loading. Typically, knee joint loading is assessed in static stance using the knee moment arm as a proxy for subsequent dynamic alignment. It remains uncertain if static alignment accurately represents actual dynamics during walking.

RESEARCH QUESTION

Is the frontal knee moment arm in stance predictive for the knee moment arm and external knee adduction moment during gait in transtibial bone-anchored prosthesis users?

METHODS

In this cross-sectional study, twenty-seven unilateral transtibial bone-anchored prosthesis users underwent data acquisition on the M-Gait instrumented treadmill. Static and dynamic measurements were conducted, and knee moment arm and external knee adduction moment were calculated. Pearson's correlation and linear regression analyses were performed to examine relationships between static and dynamic knee moment arms and external knee adduction moments.

RESULTS

The static knee moment arm showed significant associations with dynamic knee moment arm at the ground reaction force peaks (First: r=0.60, r2=35%, p<0.001; Second: r=0.62, r2=38%, p=0.001) and knee adduction moment (First: r=0.42, r2=17%, p=0.030; Second: r=0.59, r2=35%, p=0.001). A 1 mm between-subject difference in static knee moment arm corresponded, on average, with a 0.9% difference in knee adduction moment at the first peak and a 1.5% difference at the second peak of the ground reaction force.

SIGNIFICANCE

While static alignment is important to optimize adduction moments during stance it may only partly mitigate excessive moments during gait. The fair correlation and limited percentage of explained variance underscores the importance of dynamic alignment in optimizing the body's dynamic load during walking.

[Motion analysis in lower limb exoprosthetics-possibilities and limitations]

BACKGROUND

Gait analysis is of high relevance in prosthetics as it is an essential part of the fitting process. The documentation of movement by means of videos and instrumented methods is becoming increasingly important in prosthetics as benefits of a complex prosthesis can best be shown by structured observation.

PROCEDURE

A movement analysis should always be preceded by an anamnesis and clinical examination in order to detect functional limitations of the examined person and thus to establish correlations to gait deviations. Additionally, the orthopaedic aid should be evaluated as well. In addition to walking on level ground, walking on everyday obstacles such as stairs and ramps is also of interest when observing people using prosthetic limbs. Functional tests can be used to determine the functional status more comprehensively. An instrumental-3D gait analysis is indicated for specific questions, especially regarding kinetic parameters.

Transtibial prosthetic alignment has small effects on whole-body angular momentum during functional tasks

Due to the loss of ankle function, many people with a transtibial amputation (TTA) have difficulty maintaining balance during functional tasks. Prosthetic alignment may affect how people with TTA maintain balance as it affects ground reaction forces (GRFs) and centers of pressure. We quantified the effect of prosthetic alignment on dynamic balance during several functional tasks. Ten people with TTA and 10 controls without TTA completed tasks including walking and transitioning from a chair. Participants with TTA completed all tasks with their prescribed alignment and six shifted alignments, including ±10 mm anterior/posterior, medial/lateral, and ±20 mm in the vertical direction. For each task, we quantified dynamic balance as the range of whole-body angular momentum (H→_WB) and quantified trunk range of motion (ROM) and peak GRFs. Compared to controls, participants with TTA using their prescribed alignment had a greater range of H→_WB in the sagittal plane during walking, in all planes during sit-to-stand, and in the transverse plane during stand-to-sit. These results were associated with GRF and trunk ROM differences between participant groups. Alignment only affected the range of H→_WB in the frontal plane during walking. The larger range for the tall alignment coincided with a greater difference in vertical GRF between intact and amputated legs compared to other alignments. Our findings suggest that people with TTA can adapt to small, translational, alignment changes to maintain similar levels of dynamic balance during chair transitions. Future work should investigate alignment changes during other tasks and in lower functioning individuals.

An insight into Transfemoral Prostheses: Materials, modelling, simulation, fabrication, testing, clinical evaluation and performance perspectives

INTRODUCTION

A Transfemoral prosthesis restores any limb amputated above the knee. Designing and developing a transfemoral prosthesis that is consistent with human performance is a tough task. While prosthetic components are widely available in the market, ongoing research is being conducted to develop parts that would restore the lost capability, taking into account numerous social, economic and technological considerations.

AREAS COVERED

The present paper provides a comprehensive review about the mechanical aspects and performance of transfemoral prosthesis in recent years based on the research findings on materials, manufacturing methods and evaluations for suitability of the prostheses. The fundamental terminologies as well as technical advancements are covered in order to impart a better knowledge in the area of Lower Limb prostheses. This review also provides a concise description on the role of computers, advanced software packages, sensors and other hardware components for the design, fabrication and testing of transfemoral prosthetic devices in the current environment.

EXPERT OPINION

The current state of lower limb prostheses and future research opportunities are summarised to address upcoming challenges. Based on survey of various research works, adapting modern technology may aid in the development of functional and cost-efficient prosthetic components with superior safety, comfort and quality.

Prefabricated ankle-foot orthoses for children with cerebral palsy to overcome spastic drop-foot: does orthotic ankle stiffness matter?

BACKGROUND

Spastic drop-foot is a common problem in children with cerebral palsy that may lead to tripping and falling. To improve ankle dorsiflexion in swing phase, prefabricated carbon-composite ankle-foot orthoses are commonly prescribed; by increasing ankle stiffness, these orthoses may also improve knee extension in stance.

OBJECTIVES

To compare the effect of a stiff vs. flexible prefabricated ankle-foot orthosis on sagittal plane ankle and knee kinematics and kinetics during walking.

STUDY DESIGN

Cross-sectional, repeated-measures, interventional study.

METHODS

Twenty-seven children and adolescents with cerebral palsy who had drop-foot in swing were included. Gait analysis was conducted under four conditions: barefoot, shod, with a stiff, and with a flexible orthosis. Participants were divided into two groups including children and adolescents who have a flexed knee during stance (KF, N = 12) and without flexed knee during stance (KE, N = 15).

RESULTS

Ankle dorsiflexion in swing phase was significantly improved compared with the shod condition by 6.3 degrees (SD = 3.3 degrees) only in the KE group when using the flexible orthosis. For the stiff orthosis, knee extension in stance was significantly increased by 2.4 degrees (SD = 3.3 degrees) in the KE group compared with the shod condition. No significant improvements were observed for the KF group. Further analysis indicated that only seven patients in the KF group with weak ankle plantarflexors improved knee extension while using the stiff orthosis.

CONCLUSIONS

Our results suggested that in the KE group, the flexible orthosis was best suited for patients with drop-foot without a knee extension deficit. The stiff orthosis was not suitable in this group as it caused a hyperextended knee without improving dorsiflexion in swing phase. Therefore, stiffness should be considered when prefabricated orthoses are prescribed.

Community ambulation in people with lower limb amputation: An observational cohort study

Lower limb amputation (LLA) is still a health issue requiring rehabilitation and long-term care even in industrial societies. Several studies on subjects with LLA have been focused on the efficacy of rehabilitation and factors influencing the use of prosthesis. However, literature data on the recovery of ability to walk outdoors, and thus to participate in social life in this population is limited.To investigate potential correlations between socio-demographic and clinical factors, and the use of the prosthesis for indoor and/or outdoor walking referred to as community ambulation (CA) in subjects with LLA.An observational cohort study on 687 LLA subjects was conducted. Socio-demographic and clinical characteristics of 302 subjects who received similar rehabilitative treatment with respect to the standard protocol were collected by a telephone survey with a structured questionnaire. The CA recovery, in terms of patient's autonomy and participation, assessed by Walking Handicap Scale, was considered as the main outcome.The univariate analysis demonstrated statistical significant positive correlation between CA and gender (χ2 = 3.901, P = .048); amputation level (χ2 = 24.657, P < .001); pre-LLA (χ2 = 6.338, P = .012) and current work activity (χ2 = 25.192, P < .001); prosthesis use (χ2 = 187.037, P < .01); and time from LLA (r = 0.183, P < .001); increasing age was negatively correlated with the outcome (r = -0.329, P < .001), while pain intensity was not significant. Being male (75.4%); trans-tibial (TT) amputation level (9.79%); working before (3.81%) and after LLA (7.68%); and the prosthesis use (24.63%) increased the probability of CA recovery. Multivariate binary logistic regression analysis confirmed that the prosthesis use (P < .001) and TT amputation level (P = .042) are predictors of a positive outcome (Walking Handicap Scale 4-6).These findings highlight the importance of the use of prosthesis in people with LLA for the restoration of a good capacity of participation (CA), especially in subjects with TT amputation level. The identification of predictive factors may help tailor-made rehabilitation approaches addressing an earlier reintegration to social life.

Kinesiotaping Techniques to Alter Static Load in Patients With Foot Pronation

Objective

This study aimed to assess the effect of kinesio tape (KT) application on foot pronation using the laser postural alignment system.

Methods

Twenty participants (10 females and 10 males, mean age 19.7 ± 1.2 years) with foot pronation were included in the study. The laser line projected on the participant by the laser postural alignment system showed the joint load carrying line. The location of the joint load carrying line was assessed during barefoot static standing with one foot on the force plate before KT application, immediately after application, then 24 and 48 hours later. Displacement of the load-carrying line was measured using a ruler placed tangentially to the patella and ankle joint at the level of the joint line. Weight bearing on the barefoot was assessed before KT application, immediately after, then 24 and 48 hours later.

Results

Weight bearing was not significantly changed after KT application. The load-carrying line measured using KT did not notably move with KT versus without KT in the ankle joint. Immediately after KT application, significant lateral knee joint movement was measured, but this change was not importantly 24 and 48 hours later.

Conclusion

KT was not altered in changing weight bearing or moving the lower extremity load-carrying line in people with foot pronation. KT of the foot can amplify sensory input and improve perceived comfort; therefore, it can be used with an orthotic insole in footwear.

Biomechanical analysis of stair ascent in persons with Chopart amputation

BACKGROUND

Compared to walking on level ground, ascending stairs requires a large range of motion not only of the hip and knee joint, but also of the ankle joint. The prosthesis often worn by persons with partial foot amputation largely prevents the ankle motion needed during stair ascent.

OBJECTIVES

Aim of this study was to assess subjects with a Chopart amputation utilizing a clamshell device during stair ascent to identify potential biomechanical deficits.

STUDY DESIGN

Cross-sectional study with reference group.

METHODS

Six subjects with unilateral Chopart amputation and 17 unimpaired subjects underwent three-dimensional motion analysis while ascending stairs in a step-over-step manner.

RESULTS

During weight acceptance, the involved side showed increased external hip-flexing and reduced knee-flexing moments and the sound side a higher ankle power than in the control group. The sound side showed higher external knee-flexing, dorsi-flexing, and hip-adducting moments than the controls during weight acceptance.

CONCLUSION

The mechanism observed on the involved side differs from that in controls, but is comparable to the mechanisms used by subjects with transtibial amputation reported in the literature. However, compensatory movements on the sound side take place at the ankle and knee joint, differing from subjects with more proximal amputations.

CLINICAL RELEVANCE

This study underpins the importance of adequate foot leverage and ankle function in cases of partial foot amputation, particularly in transfer situations such as stair ascent. If ankle range of motion is adequate, prosthetic/orthotic devices combining shank leverage with a hinged spring mechanism at the ankle may be promising.

Dynamic alignment using external socket reaction moments in trans-tibial amputees

BACKGROUND

Prosthetic alignment is used to optimize prosthetic functioning and comfort. Spatio-temporal and kinematic gait parameters are generally observed to guide this process. However, they have been shown to be influenced by compensations, which reduces their sensitivity to changes in alignment. Alternatively, the use of moments working at the base of the prosthetic socket, external socket reaction moments (ESRM), has been proposed to quantify prosthetic alignment.

RESEARCH QUESTION

To investigate if a predetermined kinetic alignment criterion, 0Nm averaged over the stance phase, can be used to fine-tune prosthetic alignment.

METHODS

10 transtibial amputees were included in this intervention study. Firstly, their prostheses were aligned using conventional alignment procedures. Kinetic parameters and Socket Comfort Score (SCS) were measured in this initial alignment (IA) condition. Subsequently, the coronal plane ESRM during gait was presented to the prosthetist in real time using a Gait Real-time Analysis Interactive Lab. The prosthetist iteratively adapted the prosthetic alignment towards a predetermined average ESRM during the stance phase of 0 Nm. At the Final Alignment (FA), kinetic parameters and SCS were measured again and a paired sample t-test was performed to compare ESRMs and SCSs between alignments.

RESULTS

A significant (p < 0.001) change was found in the absolute coronal plane ESRM (mean ± SD) from IA (|0.104| ± 0.058 Nm/kg) to FA (|0.012| ± 0.015 Nm/kg). In addition a significant (p < 0.001) change of the external coronal adduction knee moments was observed from IA (-0,127 ± 0.079 Nm/kg) to FA (-0.055 ± 0.089 Nm/kg), however this change was more variable among participants. On average, no significant (p = 0.37) change in the SCS was observed.

SIGNIFICANCE

While this study shows the potential of quantifying and guiding alignment with the assistance of kinetic criteria, it also suggests that a sole reliance on the ESRM as a single alignment criterion might be too simple.

Low Energy Availability, Menstrual Dysfunction, and Low Bone Mineral Density in Individuals with a Disability: Implications for the Para Athlete Population

Low energy availability, functional hypothalamic amenorrhea, and low bone mineral density are three interrelated conditions described in athletic women. Although described as the female athlete triad (Triad), males experience similar health concerns. The literature suggests that individuals with a disability may experience altered physiology related to these three conditions when compared with the able-bodied population. The goal of this review is to describe the unique implications of low energy availability, low bone mineral density, and, in females, menstrual dysfunction in individuals with a disability and their potential impact on the para athlete population. A literature review was performed linking search terms related to the three conditions with six disability categories that are most represented in para sport. Few articles were found that directly pertained to athletes, therefore, the review additionally characterizes literature found in a non-athlete population. Review of the available literature in athletes suggests that both male and female athletes with spinal cord injury demonstrate risk factors for low energy availability. Bone mineral density may also show improvements for wheelchair athletes or athletes with hemiplegic cerebral palsy when compared with a disabled non-athlete population. However, the prevalence of the three conditions and implications on the health of para athletes is largely unknown and represents a key gap in the sports medicine literature. As participation in para sport continues to increase, further research is needed to understand the impact of these three interrelated health concerns for athletes with a disability, accompanied by educational initiatives targeting athletes, coaches, and health professionals.

Benefits of an increased prosthetic ankle range of motion for individuals with a trans-tibial amputation walking with a new prosthetic foot

BACKGROUND

Individuals with trans-tibial amputation show a greater peak prosthetic ankle power (push- off) when using energy storing and returning (ESAR) prosthetic feet as compared to solid-ankle cushion-heel feet. ESAR feet further contribute to the users' body support and thus limit prosthetic ankle motion. To improve ankle motion, articulating prosthetic feet have been introduced. However, articulating feet may diminish push-off.

RESEARCH QUESTION

Does a novel prosthetic foot, with a serial layout of carbon fibre leaf springs, connected by a multi-centre joint construction, have advantages in kinematics and kinetics over a conventional ESAR prosthetic foot?> METHODS: Eleven individuals with unilateral trans-tibial amputation were fitted with the novel foot (NF) and a conventional ESAR Foot (CF) and underwent 3D gait analysis. As an additional power estimate of the prosthetic ankle, a unified, deformable, segment model approach was applied. Eleven matched individuals without impairments served as a reference.

RESULTS

The NF shows an effective prosthetic ankle range of motion that is closer to a physiologic ankle range of motion, at 31.6° as compared to 15.2° with CF (CF vs. NF p = 0.003/NF vs. Reference p = 0.171) without reducing the maximum prosthetic ankle joint moment. Furthermore, the NF showed a great increase in prosthetic ankle power (NF 2.89 W/kg vs. CF 1.48 W/kg CF vs. NF p = <0.001) and a reduction of 19% in the peak knee varus moment and 13% in vertical ground reaction forces on the sound side for NF in comparison to CF.

SIGNIFICANCE

The NF shows that serial carbon fibre leaf springs, connected by a multi-centre joint construction gives a larger ankle joint range of motion and higher ankle power than a conventional carbon fibre structure alone. Consequently load is taken off the contralateral limb, as measured by the decrease in vertical ground reaction forces and peak knee varus moment.

Sound side joint contact forces in below knee amputee gait with an ESAR prosthetic foot

The incidence of knee and hip joint osteoarthritis in subjects with below knee amputation (BK) appears significantly higher compared to unimpaired subjects, especially in the intact side. However, it is controversial if constant higher loads on the sound side are one of the major factors for an increased osteoarthritis (OA) incidence in subjects with BK, beside other risk factors, e.g. with respect to metabolism. The aim wasto investigate joint contact forces (JCF) calculated by a musculoskeletal model in the intact side and to compare it with those of unimpaired subjects and to further elucidate in how far increased knee JCF are associated with increased frontal plane knee moments. A group of seven subjects with BK amputation and a group of ten unimpaired subjects were recruited for this study. Gait data were measured by 3D motion capture and force plates. OpenSim software was applied to calculate JCF. Maximum joint angles, ground reaction forces, and moments as well as time distance parameters were determined and compared between groups showing no significant differences, with some JCF components of knee and hip even being slightly smaller in subjects with BK compared to the reference group. This positive finding may be due to the selected ESAR foot. However, other beneficial factors may also have influenced this positive result such as the general good health status of the subjects or the thorough and proper fitting and alignment of the prosthesis.

[Function of prosthesis components in lower limb amputees with bone-anchored percutaneous implants : Biomechanical aspects]

BACKGROUND

Bone anchorage of an artificial limb has been proven to be an alternative intervention for amputees when prosthesis use is seriously reduced because of stump problems. Little is known about how prosthesis components interact with bone and joints and which potential the optimum use provides with respect to quality of treatment of leg amputees.

OBJECTIVE

Does osseointegration influence the motor activity of residual limbs differently compared with socket prostheses? How should prosthesis components be aligned? What type of prosthetic knee joints should be preferred in transfemoral amputees?

MATERIAL AND METHODS

Transfer of biomechanical knowledge of socket prosthetics to bone-anchored prostheses. Pilot studies with a limited number of amputees.

RESULTS

Force transmission at the interface between the prosthesis and residual limb stump is completely different for osseointegrated fixation and socket design; however, the number of muscles available for control remains unchanged. Because the iliotibial tract is missing, bending moments of the femur are expected to be greater. Prosthetic alignment is very critical for gait pattern and the basic rules seem to be the same as for socket design. The foot position determines the knee function for below-knee amputees. The position of the femur influences the gait pattern of above-knee amputees. The lowest risk of falls and best functional properties are shown by microprocessor controlled knee joints.

CONCLUSION

Osseointegrated leg prostheses have some biomechanical advantages over the socket design. Since rehabilitation quality is clearly affected the prosthetic alignment has to be done carefully and precisely. As a rule microprocessor controlled knee joints are indicated.

Functional effects of a prosthetic torsion adapter in trans-tibial amputees during unplanned spin and step turns

BACKGROUND

Shear stress at the stump in trans-tibial amputees induced by turning movements may be reduced with the use of torsion adapters in the prosthesis.

OBJECTIVE

Monitoring the motion and kinetic effects of a regular torsion adapter in comparison to a rigid placebo in unplanned spin and step turns.

STUDY DESIGN

Single-blinded placebo-controlled cohort study.

METHODS

In total, 10 trans-tibial amputees underwent three-dimensional gait analysis in level walking and unplanned spin and step turns with a torsion adapter and with a rigid placebo.

RESULTS

Kinetic effects varied among participants. No statistically significant reduction of peak internal and peak external transverse plane moments was found for the torsion adapter in any walking condition. However, transverse plane rotation of the adapter was monitored in all participants.

CONCLUSION

Motion between the socket and the residual limb may be reduced during turns due to transverse plane motion of the torsion adapter and shear stress on the residual limb may be reduced. However, there may be good and bad responders to torsion adapters due to differences in coupling between the residual limb and the socket.

CLINICAL RELEVANCE

Strong coupling between stump and socket will help the user controlling his prosthesis. Shear stress at the stump may increase in stump-socket interface stiffness and may be the reason for residual limb problems. Torsion adapters therefore may be beneficial for comfort and stump condition in individual cases.

Physical capacity and walking ability after lower limb amputation: a systematic review

Objective: To review the influence of physical capacity on regaining walking ability and the development of walking ability after lower limb amputation.

Design: A systematic search of literature was performed. The quality of all relevant studies was evaluated according to a checklist for statistical review of general papers.

Subjects: Lower limb amputees.

Main measures: Physical capacity (expressed by aerobic capacity, anaerobic capacity, muscle force, flexibility and balance) and walking ability (expressed by the walking velocity and symmetry).

Results: A total of 48 studies that complied with the inclusion criteria were selected. From these studies there is strong evidence for deterioration of two aspects of physical capacity (muscle strength and balance) and of two aspects of walking ability (walking velocity and symmetry) after lower limb amputation. Strong evidence was found for a relation between balance and walking ability.

Conclusion: Strong evidence was only found for a relation between balance and walking ability. Evidence about a relation between other elements of physical capacity and walking ability was insufficient. Training of physical capacity as well as walking ability during rehabilitation following lower limb amputation should not be discouraged since several parameters have been shown to be reduced after amputation, although their relation to regaining walking ability and to the development of walking ability remains unclear.

Influence of Shoe-heel Height of the Trans-tibial Prosthesis on Static Standing Biomechanics

Shoe-heel height has great influence on lower-limb amputees' biomechanics during static standing. This article mainly considers the load line of the prosthetic side in the sagittal plane and the electromyogram (EMG) data of the lower limb muscles. The results indicate that the load line and the EMG are greatly influenced by the shoe-heel height, however, the amputee subconsciously adjusts his standing manner to make himself more comfortable and natural. This will provide references for prosthesis design and alignment setting.

The influence of sole wedges on frontal plane knee kinetics, in isolation and in combination with representative rigid and semi-rigid ankle-foot-orthoses

BACKGROUND

In earlier stages of knee osteoarthritis orthotic treatments with knee orthoses or modified footwear are often considered. Although the load reducing effects of knee orthoses have been well established, wearing modified footwear would be more comfortable for the patient and less encumbering. The effect of modified footwear on the frontal load of the knee is controversial. This article describes the effect of medial or lateral shoe wedges alone or together with two different types of ankle-stabilizing orthoses.

METHODS

The effect on frontal knee loading was measured during standing and walking with medially and laterally placed wedges under the sole of the shoe. The wedges were also combined with two types of orthotic devices - an Ankle-Foot-Orthosis that was rigid in the frontal plane but allowed unrestricted sagittal plane motion and an ankle support that was semi-rigid in the frontal plane. Joint loading of 10 healthy persons (mean (standard deviation): age 34 (9) years, height 178 (4)cm, mass 73 (9)kg) was investigated by means of a special measuring device that accurately determines static loads (Lasar Posture) and with instrumented gait analysis (Vicon/Kistler).

FINDINGS

Using a lateral wedge under the sole of the shoe (without orthotic support) showed no significant reduction in the mean maximal knee moment in the frontal plane. Adding an Ankle-Foot-Orthosis that is rigid in the frontal plane resulted in significant reduction in the maximal frontal moment from 0.54 Nm/kg to 0.38Nm/kg (p0.01). Using a medial wedge, without and with Ankle-Foot-Orthosis, produced a significant increase in the maximal frontal moment to 0.59 Nm/kg (p0.05) or 0.67 Nm/kg (p0.01), respectively.

INTERPRETATION

These results suggest that the application of a sole wedge significantly influences frontal knee loading when used in combination with an Ankle-Foot-Orthosis that is rigid in the frontal plane.

Usability of gait analysis in the alignment of trans-tibial prostheses: a clinical study

The purpose of the study was to investigate which systematic effects of prosthetic misalignment could be observed with the use of the SYBAR system. The alignment of the prosthesis of five well-trained unilateral trans-tibial amputees was changed 15 degrees in magnitude in varus, valgus, flexion, extension, endorotation, exorotation, dorsal flexion, and plantar flexion. Subjects walked over a distance of 8 m at a self-selected walking speed with the alignment of the prosthesis as it was at the start of the experiment (reference) and with each changed alignment. Two video cameras (frontal and sagittal) and a force plate of the SYBAR system (Noldus Information Technology, The Netherlands) were used to capture gait characteristics of the subjects. Temporal and spatial characteristics, the magnitude and timing of the ground reaction force (GRF), and the external joint moments were derived from these data. Despite the substantial perturbations to prosthetic alignment, only a few effects were observed in the temporal and spatial characteristics of gait, the magnitude and timing of the GRF, and the external joint moments. Only the pattern of the ground reaction force in the mediolateral direction and the joint moment around the ankle in the frontal plane during terminal stance showed a systematic effect when the alignment was set into varus and valgus or exorotation. It was concluded that using the SYBAR system in this study revealed little effect of perturbations in prosthetic alignment, for this group of patients, and for the selected parameters. It was questioned whether this is due to the relatively low resolution of the SYBAR system or the capacity of the well-trained subjects to compensate for the disturbance in alignment. It was suggested that the usability of the SYBAR system in clinical settings should be further explored.