Assessment of amputee socket–stump–residual bone kinematics during strenuous activities using Dynamic Roentgen Stereogrammetric Analysis

Application of ultrasound to monitor in vivo residual bone movement within transtibial prosthetic sockets

Transtibial prosthetic users do often struggle to achieve an optimal prosthetic fit, leading to residual limb pain and stump-socket instability. Prosthetists face challenges in objectively assessing the impact of prosthetic adjustments on residual limb loading. Understanding the mechanical behaviour of the pseudo-joint formed by the residual bone and prosthesis may facilitate prosthetic adjustments and achieving optimal fit. This study aimed to assess the feasibility of using B-mode ultrasound to monitor in vivo residual bone movement within a transtibial prosthetic socket during different stepping tasks. Five transtibial prosthesis users participated, and ultrasound images were captured using a Samsung HM70A system during five dynamic conditions. Bone movement relative to the socket was quantified by tracking the bone contour using Adobe After-Effect. During the study a methodological adjustment was made to improve data quality, and the first two participants were excluded from analysis. The remaining three participants exhibited consistent range of motion, with a signal to noise ratio ranging from 1.12 to 2.59. Medial-lateral and anterior-posterior absolute range of motion varied between 0.03 to 0.88 cm and 0.14 to 0.87 cm, respectively. This study demonstrated that it is feasible to use B-mode ultrasound to monitor in vivo residual bone movement inside an intact prosthetic socket during stepping tasks.

Quantifying Bone and Skin Movement in the Residual Limb-Socket Interface of Individuals With Transtibial Limb Loss Using Dynamic Stereo X-Ray: Protocol for a Lower Limb Loss Cadaver and Clinical Study

BACKGROUND

Relative motion between the residual limb and socket in individuals with transtibial limb loss can lead to substantial consequences that limit mobility. Although assessments of the relative motion between the residual limb and socket have been performed, there remains a substantial gap in understanding the complex mechanics of the residual limb-socket interface during dynamic activities that limits the ability to improve socket design. However, dynamic stereo x-ray (DSX) is an advanced imaging technology that can quantify 3D bone movement and skin deformation inside a socket during dynamic activities.

OBJECTIVE

This study aims to develop analytical tools using DSX to quantify the dynamic, in vivo kinematics between the residual limb and socket and the mechanism of residual tissue deformation.

METHODS

A lower limb cadaver study will first be performed to optimize the placement of an array of radiopaque beads and markers on the socket, liner, and skin to simultaneously assess dynamic tibial movement and residual tissue and liner deformation. Five cadaver limbs will be used in an iterative process to develop an optimal marker setup. Stance phase gait will be simulated during each session to induce bone movement and skin and liner deformation. The number, shape, size, and placement of each marker will be evaluated after each session to refine the marker set. Once an optimal marker setup is identified, 21 participants with transtibial limb loss will be fitted with a socket capable of being suspended via both elevated vacuum and traditional suction. Participants will undergo a 4-week acclimation period and then be tested in the DSX system to track tibial, skin, and liner motion under both suspension techniques during 3 activities: treadmill walking at a self-selected speed, at a walking speed 10% faster, and during a step-down movement. The performance of the 2 suspension techniques will be evaluated by quantifying the 3D bone movement of the residual tibia with respect to the socket and quantifying liner and skin deformation at the socket-residuum interface.

RESULTS

This study was funded in October 2021. Cadaver testing began in January 2023. Enrollment began in February 2024. Data collection is expected to conclude in December 2025. The initial dissemination of results is expected in November 2026.

CONCLUSIONS

The successful completion of this study will help develop analytical methods for the accurate assessment of residual limb-socket motion. The results will significantly advance the understanding of the complex biomechanical interactions between the residual limb and the socket, which can aid in evidence-based clinical practice and socket prescription guidelines. This critical foundational information can aid in the development of future socket technology that has the potential to reduce secondary comorbidities that result from complications of poor prosthesis load transmission.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/57329.

Constitutive parameter identification of transtibial residual limb soft tissue using ultrasound indentation and shear wave elastography

Finite element analysis (FEA) can be used to evaluate applied interface pressures and internal tissue strains for computational prosthetic socket design. This type of framework requires realistic patient-specific limb geometry and constitutive properties. In recent studies, indentations and inverse FEA with MRI-derived 3D patient geometries were used for constitutive parameter identification. However, long computational times and use of specialized equipment presents challenges for clinical, deployment. In this study, we present a novel approach for constitutive parameter identification using a combination of FEA, ultrasound indentation, and shear wave elastography. Local shear modulus measurement using elastography during an ultrasound indentation experiment has particular significance for biomechanical modeling of the residual limb since there are known regional dependencies of soft tissue properties such as varying levels of scarring and atrophy. Beyond prosthesis design, this work has broader implications to the fields of muscle health and monitoring of disease progression.

An Instrumented Printed Insert for Continuous Monitoring of Distal Limb Motion in Suction and Elevated Vacuum Sockets

A suction or elevated vacuum prosthetic socket that loses vacuum pressure may cause excessive limb motion, putting the user at risk of skin irritation, gait instability and injury. The purpose of this research was to develop a method to monitor distal limb motion and then test a small group of participants wearing suction sockets to identify variables that strongly influenced motion. A thin plastic insert holding two inductive sensor antennae was designed and printed. Inserts were placed in suction sockets made for four participants who regularly used suction or elevated vacuum suspension. Participants wore a liner with a trace amount of iron powder in the elastomer that served as a distance target for the sensors. In-lab testing demonstrated that the sensed distance increased when participants added socks and decreased when they removed socks, demonstrating proper sensor performance. Results from take-home testing (3–5 days) suggest that research investigation into cyclic limb motion for sock presence v. absence should be pursued, as should the influence of bodily position between bouts of walking. These variables may have an important influence on suspension. Long-term monitoring may provide clinical insight to improve fit and to enhance suction and elevated vacuum technology.

Within-subject effects of standardized prosthetic socket modifications on physical function and patient-reported outcomes

Background

Among the challenges of living with lower limb loss is the increased risk of long-term health problems that can be either attributed directly to the amputation surgery and/or prosthetic rehabilitation or indirectly to a disability-induced sedentary lifestyle. These problems are exacerbated by poorly fit prosthetic sockets. There is a knowledge gap regarding how the socket design affects in-socket mechanics and how in-socket mechanics affect patient-reported comfort and function. The objectives of this study are (1) to gain a better understanding of how in-socket mechanics of the residual limb in transfemoral amputees are related to patient-reported comfort and function, (2) to identify clinical tests that can streamline the socket design process, and (3) to evaluate the efficacy and cost of a novel, quantitatively informed socket optimization process.

Methods

Users of transfemoral prostheses will be asked to walk on a treadmill wearing their current socket plus 8 different check sockets with designed changes in different structural measurements that are likely to induce changes in residual limb motion, skin strain, and pressure distribution within the socket. Dynamic biplane radiography and pressure sensors will be used to measure in-socket residual limb mechanics. Patient-reported outcomes will also be collected after wearing each socket. The effects of in-socket mechanics on both physical function and patient-reported outcomes (aim 1) will be assessed using a generalized linear model. Partial correlation analysis will be used to examine the association between research-grade measurements and readily available clinical measurements (aim 2). In order to compare the new quantitative design method to the standard of care, patient-reported outcomes and cost will be compared between the two methods, utilizing the Wilcoxon-Mann-Whitney non-parametric test (aim 3).

Discussion

Knowledge on how prosthetic socket modifications affect residual bone and skin biomechanics itself can be applied to devise future socket designs, and the methodology can be used to investigate and improve such designs, past and present. Apart from saving time and costs, this may result in better prosthetic socket fit for a large patient population, thus increasing their mobility, participation, and overall health-related quality of life.

Trial registration

ClinicalTrials.gov NCT05041998. Date of registration: Sept 13, 2021.

Digital healthcare technologies: Modern tools to transform prosthetic care

INTRODUCTION

Digital healthcare technologies are transforming the face of prosthetic care. Millions of people with limb loss around the world do not have access to any form of rehabilitative healthcare. However, digital technologies provide a promising solution to augment the range and efficiency of prosthetists.

AREAS COVERED

The goal of this review is to introduce the digital technologies that have the potential to change clinical methods in prosthetic healthcare. Our target audience are researchers who are unfamiliar with the field of prostheses in general, especially with the newest technological developments. This review addresses technologies for: scanning of amputated limbs, limb-to-socket rectification, additive manufacturing of prosthetic sockets, and quantifying patient response to wearing sockets. This review does not address biomechatronic prostheses or biomechanical design practices.

EXPERT OPINION

Digital technologies will enable affordable prostheses to be built on a scale larger than with today's clinical practices. Large technological gaps need to be overcome to enable the mass production and distribution of prostheses digitally. However, recent advances in computational methods and CAD/CAM technologies are bridging this gap faster than ever before. We foresee that these technologies will return mobility and economic opportunity to amputees on a global scale in the near future.

Residual limb shear strain during gait is correlated with patient reported outcomes for persons with transfemoral amputation

The purpose of this study was to measure residual limb skin strain and strain rate within the socket during gait in individuals with a transfemoral amputation and to determine if skin strain during gait is related to patient-reported comfort and function. It was hypothesized that greater skin strain and skin strain rate would correlate to worse patient-reported outcomes. It was also hypothesized that skin strain would progressively increase from the distal to the proximal end of the residuum and maximum strain would occur shortly after heel strike. Dynamic biplane radiography (DBR), combined with conventional motion capture, was used to measure skin deformation within the socket during treadmill walking for 10 persons with unilateral transfemoral amputation. The questionnaire for persons with a transfemoral amputation (Q-TFA) was administered to assess prosthetic use, mobility, health problems, and global health. Q-TFA Prosthetic Use score and Problem score were negatively correlated with the peak shear strains in the proximal and distal regions of the residuum, respectively. Maximum shear strain increased progressively from proximal to distal regions of the residual limb. Within-subject variability in shear strain waveforms during gait was 0.7% or less, but between-subject variability was 3.3% to 5.0% shear. This study demonstrates that skin shear within the socket of persons with transfemoral amputation can be measured during gait using DBR and the results suggest that greater skin shear in the proximal region of the socket is related to decreased prosthetic use.

Trends and Opportunities in Health Economic Evaluations of Prosthetic Care Innovations

Overcoming obstacles to prosthetic fittings requires frequent tryouts of sockets and components. Repetitions of interventions are upsetting for users and place substantial economic burden on healthcare systems. Encouraging prosthetic care innovations capable of alleviating clinical and financial shortcomings of socket-based solutions is essential. Nonetheless, evidence of socio-economic benefits of an innovation are required to facilitate access to markets. Unfortunately, complex decisions must be made when allocating resources toward the most relevant health economic evaluation (HEE) at a given stage of development of an innovation. This paper first, aimed to show the importance and challenges of HEEs of intervention facilitating prosthetic fittings. Next, the main trends in HEEs at various phases of product development and clinical acceptance of prosthetic care innovations were outlined. Then, opportunities for a basic framework of a preliminary cost-utility analysis (CUA) during the mid-stage of development of prosthetic care innovations were highlighted. To do this, fundamental and applied health economic literature and prosthetic-specific publications were reviewed to extract and analyse the trends in HEEs of new medical and prosthetic technologies, respectively. The findings show there is consensus around the weaknesses of full CUAs (e.g., lack of timeliness, resource-intensive) and strengths of preliminary CUAs (e.g., identify evidence gaps, educate design of full CUA, fast-track approval). However, several obstacles must be overcome before preliminary CUA of prosthetic care innovations will be routinely carried out. Disparities of methods and constructs of usual preliminary CUA are barriers that could be alleviated by a more standardized framework. The paper concludes by identifying that there are opportunities for the development of a basic framework of preliminary CUA of prosthetic care innovations. Ultimately, the collaborative design of a framework could simplify selection of the methods, standardise outcomes, ease comparisons between innovations and streamline pathways for adoption. This might facilitate access to economical solutions that could improve the life of individuals suffering from limb loss.

Effects of Prosthetic Socket Design on Residual Femur Motion Using Dynamic Stereo X-Ray - A Preliminary Analysis

Individuals with transfemoral amputation experience relative motion between their residual limb and prosthetic socket, which can cause inefficient dynamic load transmission and secondary comorbidities that limit mobility. Accurately measuring the relative position and orientation of the residual limb relative to the prosthetic socket during dynamic activities can provide great insight into the complex mechanics of the socket/limb interface. Five participants with transfemoral amputation were recruited for this study. All participants had a well-fitting, ischial containment socket and were also fit with a compression/release stabilization socket. Participants underwent an 8-wk, randomized crossover trial to compare differences between socket types. Dynamic stereo x-ray was used to quantify three-dimensional residual bone kinematics relative to the prosthetic socket during treadmill walking at self-selected speed. Comfort, satisfaction, and utility were also assessed. There were no significant differences in relative femur kinematics between socket types in the three rotational degrees of freedom, as well as anterior-posterior and medial-lateral translation (p > 0.05). The ischial containment socket demonstrated significantly less proximal-distal translation (pistoning) of the femur compared to the compression/release stabilization socket during the gait cycle (p < 0.05), suggesting that the compression/release stabilization socket provided less control of the residual femur during distal translation. No significant differences in comfort and utility were found between socket types (p > 0.05). The quantitative, dynamic analytical tools used in the study were sensitive to distinguish differences in three-dimensional residual femur motion between two socket types, which can serve as a platform for future comparative effectiveness studies of socket technology.

A sensor to monitor limb depth in transtibial sockets with locking pin suspension: a technical note

BACKGROUND

Monitoring of limb depth in transtibial sockets may provide useful information toward patient education and care.

OBJECTIVE

The objective was to develop a sensor to detect the depth of a locking pin in the shuttle lock of a transtibial socket and to monitor the small motions between ratchet clicks during ambulation.

STUDY DESIGN

Controlled bench testing and single-participant study.

METHODS

A copper wire coil positioned beneath the socket shuttle lock was used with an inductive sensing chip to monitor locking pin depth. A custom jig was used to calibrate the sensor and bench test the system. Repeatability, drift, and the effects of pin length, carbon fiber presence, temperature change, and pin angulation on sensor performance were tested. Testing was conducted on a participant wearing an adjustable socket, walking with the panels at four different radial positions.

RESULTS

The sensor demonstrated a root mean square error of 0.21% of the full-scale output. Different pins, different pin lengths, and the presence of carbon fiber affected calibration, indicating that the sensor must be calibrated to the individual user's socket and pin. Ratchet clicks and cyclic motion between clicks during walking were evident in the data. During participant testing, enlarging the socket at 1.00 mm radial increments caused significant changes in pin peak-to-peak distance (up and down motion) within a step.

CONCLUSIONS

The sensor is sufficiently accurate to pursue studies investigating utility of the data toward clinical monitoring of socket fit.

Motion of the residual femur within the socket during gait is associated with patient-reported problems in transfemoral amputees

The purpose of this study was to provide a quantitative description of residual femur motion within the socket during gait and to explore the relationship between residual femur motion and patient-reported comfort and function. It was hypothesized that increased residual bone movement would correlate to worse patient-reported comfort and function. The secondary goals were to assess within-subject step-to-step variability and between-subject variability in residual femur motion within the socket during gait. Dynamic biplane radiography, combined with conventional motion capture, was used to measure residual femur motion within the socket during treadmill walking for 10 unilateral transfemoral amputees. The questionnaire for persons with a transfemoral amputation (Q-TFA) was administered to assess prosthetic use, mobility, health problems, and global health. Increased femur pistoning (proximal-distal translation relative to the socket) correlated with worsening Q-TFA problem and global scores (ρ = 0.741, p = 0.04 and ρ = -0.783, p = 0.02, respectively). Average residual femur rotation ROMs were 7.3°±3.7°, 10.8°±4.4°, and 7.7°±4.8° for anterior tilt, internal-external rotation, and varus-valgus, respectively. Average residual femur translation ROMs were 8.6 mm ± 3.0 mm, 28.4 mm ± 13.9 mm, and 20.4 mm ± 7.2 mm for medial-lateral, pistoning, and anterior-posterior directions, respectively. Within-subject rotational and translational variability during gait averaged 2.8° and 2.0 mm or less, whereas the between-subject variability was up to 9.4° and 18.6 mm, which demonstrates residual femur motion relative to the socket is repeatable within subjects, but inconsistent across subjects during gait. The results suggest residual bone motion within the socket is a potential mechanism behind patient-reported problems and suggests a target for intervention aimed at improving transfemoral amputee quality of life.

Exploring the role of transtibial prosthetic use in deep tissue injury development: a scoping review

Background

The soft tissue of the residual limb in transtibial prosthetic users encounters unique biomechanical challenges. Although not intended to tolerate high loads and deformation, it becomes a weight-bearing structure within the residuum-prosthesis-complex. Consequently, deep soft tissue layers may be damaged, resulting in Deep Tissue Injury (DTI). Whilst considerable effort has gone into DTI research on immobilised individuals, only little is known about the aetiology and population-specific risk factors in amputees. This scoping review maps out and critically appraises existing research on DTI in lower-limb prosthetic users according to (1) the population-specific aetiology, (2) risk factors, and (3) methodologies to investigate both.

Results

A systematic search within the databases Pubmed, Ovid Excerpta Medica, and Scopus identified 16 English-language studies. The results indicate that prosthetic users may be at risk for DTI during various loading scenarios. This is influenced by individual surgical, morphological, and physiological determinants, as well as the choice of prosthetic componentry. However, methodological limitations, high inter-patient variability, and small sample sizes complicate the interpretation of outcome measures. Additionally, fundamental research on cell and tissue reactions to dynamic loading and on prosthesis-induced alterations of the vascular and lymphatic supply is missing.

Conclusion

We therefore recommend increased interdisciplinary research endeavours with a focus on prosthesis-related experimental design to widen our understanding of DTI. The results have the potential to initiate much-needed clinical advances in surgical and prosthetic practice and inform future pressure ulcer classifications and guidelines.

A new method to quantify liner deformation within a prosthetic socket for below knee amputees

Many amputees who wear a leg prosthesis develop significant skin wounds on their residual limb. The exact cause of these wounds is unclear as little work has studied the interface between the prosthetic device and user. Our research objective was to develop a quantitative method for assessing displacement patterns of the gel liner during walking for patients with transtibial amputation. Using a reflective marker system and a custom clear socket, evaluations were conducted with a clear transparent test socket mounted over a plaster limb model and a deformable limb model. Distances between markers placed on the limb were measured with a digital caliper and then compared with data from the motion capture system. Additionally, the rigid plaster set-up was moved in the capture volume to simulate walking and evaluate if inter-marker distances changed in comparison to static data. Dynamic displacement trials were then collected to measure changes in inter-marker distance due to vertical elongation of the gel liner. Static and dynamic inter-marker distances within day and across days confirmed the ability to accurately capture displacements using this new approach. These results encourage this novel method to be applied to a sample of amputee patients during walking to assess displacements and the distribution of the liner deformation within the socket. The ability to capture changes in deformation of the gel liner will provide new data that will enable clinicians and researchers to improve design and fit of the prosthesis so the incidence of pressure ulcers can be reduced.

Prosthesis donning and doffing questionnaire: Development and validation

OBJECTIVES

To develop a questionnaire that specifically evaluates the ability of trans-tibial amputees to don and doff a prosthesis and to investigate the psychometric properties of the newly developed questionnaire.

BACKGROUND

Prosthesis should be donned and doffed few times during the day and night; thus, it is important to measure ease of donning and doffing.

STUDY DESIGN

A cross-sectional study.

METHODS

The questionnaire was designed and evaluated by a group of experts. The final questionnaire was administered to 50 individuals with trans-tibial amputation. A test-retest study was also conducted on 20 amputees to assess the repeatability of questionnaire items.

RESULTS

The prosthesis donning and doffing questionnaire was developed and tested through a pilot study. Based on Kappa index, the questionnaire items showed correlation coefficients greater than 0.7, which indicate good reliability and repeatability. The majority of the participants had good hand dexterity (80%) and could perform all types of grasps. The mean satisfaction scores with donning and doffing were 69.9 and 81.4, respectively. Most of the respondents needed to don and doff the prosthesis 3.44 times per day. Based on a 7-point score, the total scores ranged between 3 and 7.

CONCLUSION

The prosthesis donning and doffing questionnaire items showed good psychometric properties. A scoring method was suggested based on the pilot sample, which requires further evaluation to be able to differentiate between more suspension types. A larger international multicenter evaluation is required in the future to measure the responsiveness of the scales. This questionnaire will be useful in the evaluation of the ability of amputees to don and doff a trans-tibial limb prosthesis. Clinical relevance Donning and doffing of prostheses are challenging tasks for many lower limb amputees. The prosthesis donning and doffing questionnaire, on its own or combined with other prosthetic evaluation questionnaires, has the potential to help manufacturers, clinicians, and researchers gain knowledge and improve the donning and doffing qualities of prostheses.

A combined kinematic and kinetic analysis at the residuum/socket interface of a knee-disarticulation amputee

The bespoke interface between a lower limb residuum and a prosthetic socket is critical for an amputee's comfort and overall rehabilitation outcomes. Analysis of interface kinematics and kinetics is important to gain full understanding of the interface biomechanics, which could aid clinical socket fit, rehabilitation and amputee care. This pilot study aims to investigate the dynamic correlation between kinematic movement and kinetic stresses at the interface during walking tests on different terrains. One male, knee disarticulation amputee participated in the study. He was asked to walk on both a level surface and a 5° ramped surface. The movement between the residuum and the socket was evaluated by the angular and axial couplings, based on the outputs from a 3D motion capture system. The corresponding kinetic stresses at anterior-proximal (AP), posterior-proximal (PP) and anterior-distal (AD) locations of the residuum were measured, using individual stress sensors. Approximately 8° of angular coupling and up to 32 mm of axial coupling were measured when walking on different terrains. The direction of the angular coupling shows strong correlation with the pressure difference between the PP and AP sensors. Higher pressure was obtained at the PP location than the AP location during stance phase, associated with the direction of the angular coupling. A strong correlation between axial coupling length, L, and longitudinal shear was also evident at the PP and AD locations i.e. the shortening of L corresponds to the increase of shear in the proximal direction. Although different terrains did not affect these correlations in principle, interface kinematic and kinetic values suggested that gait changes can induce modifications to the interface biomechanics. It is envisaged that the reported techniques could be potentially used to provide combined kinematics and kinetics for the understanding of biomechanics at the residuum/socket interface, which may play an important role in the clinical assessment of prosthetic component settings, including socket fit quality.

Marker-based method to measure movement between the residual limb and a transtibial prosthetic socket

BACKGROUND

Limb movement between the residuum and socket continues to be an underlying factor in limb health, prosthetic comfort, and gait performance yet techniques to measure this have been underdeveloped.

OBJECTIVES

Develop a method to measure motion between the residual limb and a transtibial prosthetic socket.

STUDY DESIGN

Single subject, repeated measures with mathematical modeling.

METHODS

The gait of a participant with transtibial amputation was recorded using a motion capture system using a marker set that included arrays on the anterior distal tibia and the lateral epicondyle of the femur. The proximal or distal translation, anterior or posterior translation, and angular movements were quantified. A random Monte Carlo simulation based on the precision of the motion capture system and a model of the bone moving under the skin explored the technique's accuracy. Residual limb tissue stiffness was modeled as a linear spring based on data from Papaioannou et al.

RESULTS

Residuum movement relative to the socket went through ~30 mm, 18 mm, and 15° range of motion. Root mean squared errors were 5.47 mm, 1.86 mm, and 0.75° when considering the modeled bone-skin movement in the proximal or distal, anterior or posterior, and angular directions, respectively.

CONCLUSION

The measured movement was greater than the root mean squared error, indicating that this method can measure motion between the residuum and socket.

CLINICAL RELEVANCE

The ability to quantify movement between the residual limb and the prosthetic socket will improve prosthetic treatment through the evaluation of different prosthetic suspensions, socket designs, and motor control of the prosthetic interface.

The evidence-base for elevated vacuum in lower limb prosthetics: Literature review and professional feedback

BACKGROUND

An optimal suspension system can improve comfort and quality of life in people with limb loss. To guide practice on prosthetic vacuum suspension systems, assessment of the current evidence and professional opinion are required.

METHODS

PubMed, Web of Science, and Google Scholar databases were explored to find related articles. Search terms were amputees, artificial limb, prosthetic suspension, prosthetic liner, vacuum, and prosthesis. The results were refined by vacuum socket or vacuum assisted suspension or sub-atmospheric suspension. Study design, research instrument, sample size, and outcome measures were reviewed. An online questionnaire was also designed and distributed worldwide among professionals and prosthetists (www.ispoint.org, OANDP-L, LinkedIn, personal email).

FINDINGS

26 articles were published from 2001 to March 2016. The number of participants averaged 7 (SD=4) for transtibial and 6 (SD=6) for transfemoral amputees. Most studies evaluated the short-term effects of vacuum systems by measuring stump volume changes, gait parameters, pistoning, interface pressures, satisfaction, balance, and wound healing. 155 professionals replied to the questionnaire and supported results from the literature. Elevated vacuum systems may have some advantages over the other suspension systems, but may not be appropriate for all people with limb loss.

INTERPRETATION

Elevated vacuum suspension could improve comfort and quality of life for people with limb loss. However, future investigations with larger sample sizes are needed to provide strong statistical conclusions and to evaluate long-term effects of these systems.

Comparison of transhumeral socket designs utilizing patient assessment and in vivo skeletal and socket motion tracking: a case study

PURPOSE

This case study compares the impact of two prosthetic socket designs, a "traditional" transhumeral (TH) socket design and a Compression Released Stabilized (CRS) socket.

METHODS

A CRS socket was compared to the existing socket of two persons with transhumeral amputation. Comparisons included assessments of patient comfort and satisfaction with fit, as well as dynamic kinematic assessment using a novel high-speed, high-resolution, bi-plane video radiography system (XROMM, for X-ray Reconstruction of Moving Morphology).

RESULTS

Subjects were more satisfied with the comfort of the traditional sockets, although they had positive impressions about aspects of the fit and style of the CRS socket, and thought that it provided better control. Dynamic kinematic assessment revealed that the CRS socket provided better control of the residual limb within the socket, and had less slippage as compared to a traditional TH socket design.

CONCLUSIONS

The TH CRS socket provided better control of the residual limb within the socket, and had less slippage. However, participants were less satisfied with the comfort and overall utility of the CRS socket, and stated that additional fitting visits/modifications to the CRS socket were needed. It is possible that satisfaction with the CRS socket may have improved with prosthetic adjustment and more acclimation time. Implications for Rehabilitation A comfortable, good fitting prosthetic socket is the key factor in determining how long (or if) an upper limb amputee can tolerate wearing a prosthesis. This case series was a comparison of two socket designs, a 'traditional' socket design and a Compression Released Stabilized (CRS) socket design in persons with transhumeral amputation. The CRS socket provided better control of the residual limb within the socket, and had less slippage. However, its tightness made it more difficult to don. Both subjects were less satisfied with the comfort and overall utility of the CRS socket. However, satisfaction might have been improved with additional fitting visits and more acclimation time.

Transtibial prosthesis suspension systems: systematic review of literature

BACKGROUND

Today a number of prosthetic suspension systems are available for transtibial amputees. Consideration of an appropriate suspension system can ensure that amputee's functional needs are satisfied. The higher the insight to suspension systems, the easier would be the selection for prosthetists. This review attempted to find scientific evidence pertaining to various transtibial suspension systems to provide selection criteria for clinicians.

METHODS

Databases of PubMed, Web of Science, and ScienceDirect were explored to find related articles. Search terms were as follows: "Transtibial prosthesis (32), prosthetic suspension (48), lower limb prosthesis (54), below-knee prosthesis (58), prosthetic liner (20), transtibial (193), and prosthetic socket (111)". Two reviewers separately examined the papers. Study design (case series of five or more subjects, retrospective or prospective), research instrument, sampling method, outcome measures and protocols were reviewed.

FINDINGS

Based on the selection criteria, 22 articles (15 prospective studies, and 7 surveys) remained. Sweat control was found to be a major concern with the available suspension liners. Donning and doffing procedures for soft liners are also problematic for some users, particularly those with upper limb weakness. Moreover, the total surface bearing (TSB) socket with pin/lock system is favored by the majority of amputees.

INTERPRETATION

In summary, no clinical evidence is available to suggest what kind of suspension system could have an influential effect as a "standard" system for all transtibial amputees. However, among various suspension systems for transtibial amputees, the Iceross system was favored by the majority of users in terms of function and comfort.

Transtibial prosthetic socket pistoning: static evaluation of Seal-In(®) X5 and Dermo(®) Liner using motion analysis system

BACKGROUND

The method of attachment of prosthesis to the residual limb (suspension) and socket fitting is a critical issue in the process of providing an amputee with prosthesis. Different suspension methods try to minimize the pistoning movement inside the socket. The Seal-In(®) X5 and Dermo(®) Liner by Ossur are new suspension liners that intend to reduce pistoning between the socket and liner. Since the effects of these new liners on suspension are unclear, the objective of this study was to compare the pistoning effect of Seal-In(®) X5 and Dermo(®) Liner by using Vicon Motion System.

METHODS

Six transtibial amputees, using both the Iceross Seal-In(®) X5 and the Iceross Dermo(®) Liner, participated in the study. The vertical displacement (pistoning) was measured between the liner and socket in single limb support on the prosthetic limb (full-weight bearing), double limb support (semi-weight bearing), and non-weight bearing on the prosthetic limb, and also under three static vertical loading conditions (30 N, 60 N, and 90 N).

FINDINGS

The results demonstrated that the pistoning within the socket when Seal-In(®) X5 was used, decreased by 71% in comparison to the Iceross Dermo(®) Liner. In addition, a significant difference between the two liners under different static conditions was found (p<0.05).

INTERPRETATION

Participants needed to put in extra effort for donning and doffing the prosthesis with Seal-In(®) X5; however, this type of liner provided less pistoning. The new approach that uses the motion analysis system in this study might be an alternative for measuring the pistoning effect in the prosthetic socket.

A new approach for the pistoning measurement in transtibial prosthesis

BACKGROUND

Good suspension lessens the pistoning (vertical displacement) of the residual limb inside the prosthetic socket. Several methods are used for measuring the pistoning.

STUDY DESIGN

Clinical trial.

OBJECTIVES

To introduce and evaluate a new simple method for measuring the pistoning between the soft liner and socket in transtibial prostheses.

METHODS

Five transtibial prostheses with Iceross silicone liner and shuttle lock were made for the subjects. The pistoning was measured between the liner and socket by a photographic method in single limb support on the prosthetic limb (full weight bearing), non-weight bearing and under three static axial loading conditions (30, 60 and 90 N).

RESULTS

This new method enabled us to measure the pistoning between the liner and prosthetic socket. The reproducibility of measurements in different trials of one session and between two sessions by two observers was shown to be high. The average of displacement between the liner and socket was about 9 mm in non-weight bearing compared with full weight bearing. Furthermore, as we expected, the average of pistoning increased consistently by adding the loads.

CONCLUSIONS

This new method provides for easy and inexpensive determination of pistoning between the liner and socket by every prosthetist in clinical settings.