Microprocessor-controlled Knee Research Articles

An enhancement of the Genium™ microprocessor-controlled knee improves safety and different aspects of the perceived prosthetic experience for unilateral and bilateral users.

Bilateral microprocessor-controlled prosthetic knee (MPK) users have unique needs in traversing environmental barriers compared to unilateral users. An enhancement to the Genium™/Genium X3™ MPK which included an updated ruleset, hydraulics, and new bilateral parameter presets was made to improve safety while stumbling and the smoothness of gait for all users while also improving the experience of bilateral users. The purpose of the study was to evaluate the effectiveness of the enhancements in a sample with unilateral and bilateral amputation. A convenience sample of MPK users was recruited from two sites in the USA in two phases. Assessments included the L-Test of Functional Mobility, Activity-specific Balance Confidence Scale, Prosthetic Limb User Survey of Mobility, a study-specific questionnaire, and the Comparative Activities of Daily Living (ADL) Questionnaire. Statistical significance of extracted data was tested with the Wilcoxon Rank-Sum Test for independent data and Wilcoxon Signed-Rank for paired data with an a priori significance level of p < 0.05. Unilateral subjects were age-matched to the group of bilateral subjects for between-groups and within-groups analyses. Twenty-six subjects (n = 26) were enrolled. Stumble frequency reduced 85% from 16.0 ± 39.7 to 2.4 ± 2.3 (p = 0.008) between baseline and final assessment overall. The bilateral group reported 50% (p = 0.009) and 57% (p = 0.009) greater relative improvement in patient-reported ease and safety, respectively, of completing ADLs compared to the unilateral group. The unilateral group reported residual limb pain and low back pain reduced from 2.3 to 1.4 (p = 0.020) and 3.8 to 1.8 (p = 0.027), respectively, whereas the bilateral group did not. Substantial reductions in stumbles, residual limb pain, and back pain were shown overall. These reductions were driven by the unilateral group who also showed improvements in comfort, exertion, and concentration while walking. The enhancements to the knee likely reduced some gait asymmetry for unilateral users. Improvements in patient-reported ease and safety of completing ADLs were shown overall and were driven by the bilateral group. This study shows further improvement in patient experience is achievable through innovation in MPK technology even for patients who appear to be functioning well.

Development of an Integrated Powered Hip and Microprocessor-Controlled Knee for a Hip-Knee-Ankle-Foot Prosthesis.

Hip-knee-ankle-foot prostheses (HKAF) are full lower-limb devices for people with hip amputations that enable individuals to regain their mobility and move freely within their chosen environment. HKAFs typically have high rejection rates among users, as well as gait asymmetry, increased trunk anterior-posterior lean, and increased pelvic tilt. A novel integrated hip-knee (IHK) unit was designed and evaluated to address the limitations of existing solutions. This IHK combines powered hip and microprocessor-controlled knee joints into one structure, with shared electronics, sensors, and batteries. The unit is also adjustable to user leg length and alignment. ISO-10328:2016 standard mechanical proof load testing demonstrated acceptable structural safety and rigidity. Successful functional testing involved three able-bodied participants walking with the IHK in a hip prosthesis simulator. Hip, knee, and pelvic tilt angles were recorded and stride parameters were analyzed from video recordings. Participants were able to walk independently using the IHK and data showed that participants used different walking strategies. Future development of the thigh unit should include completion of a synergistic gait control system, improved battery-holding mechanism, and amputee user testing.

Using embedded prosthesis sensors for clinical gait analyses in people with lower limb amputation: A feasibility study

BackgroundBiomechanical gait analyses are typically performed in laboratory settings, and are associated with limitations due to space, marker placement, and tasks that are not representative of the real-world usage of lower limb prostheses. Therefore, the purpose of this study was to investigate the possibility of accurately measuring gait parameters using embedded sensors in a microprocessor-controlled knee joint. MethodsTen participants were recruited for this study and equipped with a Genium X3 prosthetic knee joint. They performed level walking, stair/ramp descent, and ascent. During these tasks, kinematics and kinetics (sagittal knee and thigh segment angle, and knee moment) were recorded using an optical motion capture system and force plates (gold standard), as well as the prosthesis-embedded sensors. Root mean square errors, relative errors, correlation coefficients, and discrete outcome variables of clinical relevance were calculated and compared between the gold standard and the embedded sensors. FindingsThe average root mean square errors were found to be 0.6°, 5.3°, and 0.08 Nm/kg, for the knee angle, thigh angle, and knee moment, respectively. The average relative errors were 0.75% for the knee angle, 11.67% for the thigh angle, and 9.66%, for the knee moment. The discrete outcome variables showed small but significant differences between the two measurement systems for a number of tasks (higher differences only at the thigh). InterpretationThe findings highlight the potential of prosthesis-embedded sensors to accurately measure gait parameters across a wide range of tasks. This paves the way for assessing prosthesis performance in realistic environments outside the lab.

A new approach to a powered knee prosthesis: Layering powered assistance onto strictly passive prosthesis behavior.

This article describes a novel approach to the control of a powered knee prosthesis where the control system provides passive behavior for most activities and then provides powered assistance only for those activities that require them. The control approach presented here is based on the categorization of knee joint function during activities into four behaviors: resistive stance behavior, active stance behavior, ballistic swing, and non-ballistic swing. The approach is further premised on the assumption that healthy non-perturbed swing-phase is characterized by a ballistic swing motion, and therefore, a replacement of that function should be similarly ballistic. The control system utilizes a six-state finite-state machine, where each state provides different constitutive behaviors (concomitant with the four aforementioned knee behaviors) which are appropriate for a range of activities. Transitions between states and torque control within states is controlled by user motion, such that the control system provides, to the extent possible, knee torque behavior as a reaction to user motion, including for powered behaviors. The control system is demonstrated on a novel device that provides a sufficiently low impedance to enable a strictly passive ballistic swing-phase, while also providing sufficiently high torque to offer powered stance-phase knee-extension during activities such as step-over stair ascent. Experiments employing the knee and control system on an individual with transfemoral amputation are presented that compare the functionality of the power-supplemented nominally passive system with that of a conventional passive microprocessor-controlled knee prosthesis.

Effect of slope in an immersive virtual environment on segmental asymmetry in people with femoral amputation and a microprocessor knee

Purpose The continued development of microprocessor-based knee prostheses has improved the independence of people with a femoral amputation in many environments. This study aimed to describe the effect of slopes on kinematic joint variables and segmental asymmetry. Methods Ten individuals with transfemoral amputation fitted with microprocessor-controlled knees performed 5 sessions of treadmill walking at their preferred speed in an immersive virtual environment in 5 incline conditions (Level, 3° and 6° Uphill, and 3° and 6° Downhill). The Human Body Model was used to quantify kinematic joint variables from motion capture system data. The perimeter-to-area method was used to determine the symmetry ratio of the trajectory of the leg segments in the sagittal plane Results There was a significant effect of the Uphill conditions on step length and width on the intact side and on all kinematic joint variables on both sides, although the changes differed according to the phase of the gait cycle. The segmental symmetry index was significantly modified in all slope conditions compared with Level. Conclusions Kinematic joint variables are affected by slopes; the effect was greater for the Uphill than Downhill conditions compared with the Level condition. The perimeter-to-area symmetry ratio differed from the Level condition for all slope conditions. These results indicate that, although microprocessor knees improve the autonomy of prosthesis users, work is required to improve their capacity of adaptation to varied terrain to reduce kinematic asymmetry.

A Power-Capable Knee Prosthesis With Ballistic Swing-Phase

This paper proposes a new approach to the design of a power-capable prosthesis; namely, one that expands the behavioral capability of a knee prosthesis into the powered quadrants of the power plane, without sacrificing the range of capable behaviors in the passive quadrants, relative to existing passive microprocessor-controlled knee prostheses (MPKs). It is well-known that swing-phase knee motion during walking in healthy human gait results from the combination of inertial coupling between the thigh and shank, gravitational effects, and passive behavior at the knee. Motor-actuated prostheses with powered stance and swing capabilities have recently emerged, but none have been shown to provide a strictly-passive biomimetic swing-phase. This paper describes an approach that enables expansion of knee behavior into the powered quadrants of the power plane, without sacrificing the ability to provide a strictly-passive biomimetic swing-phase, or the passive stance-phase behaviors provided by passive MPKs.

What a Knee Should Be: A Pilot Study on the Perspectives of Highly Active Prosthetic Users

ABSTRACT Introduction In recent years, microprocessor-controlled knees have become available to people with lower-limb amputation. Although they may be associated with greater economic benefits and improved clinical outcomes when compared with non-microprocessor-controlled knees, some individuals discontinue use or do not utilize all the functions they provide. Better understanding of how the relationship between human factors and prosthetic function influences peoples' experience is needed to make microprocessor-controlled knees and their functions more accessible to users. Objectives The aims of this study were to explore the prosthetic history of highly active individuals with transfemoral amputation and identify the factors important for prosthetic satisfaction, use, and acceptance, as well as opportunities in advanced prosthetic development. Study Design A qualitative study design was used. Methods Semistructured interviews were conducted with five highly active people with transfemoral amputation using microprocessor-controlled knees. Results We identified several factors important for prosthetic satisfaction, use, and acceptance: 1) feeling in control of prosthesis, 2) consistency in functions of prosthesis, 3) intuitive prosthesis, 4) feeling unrestricted by prosthesis, 5) spontaneity, 6) easy to walk and change speed, 7) quiet function, 8) easy to trigger and transition between modes, 9) individually relevant modes, 10) harmonious function with ankle, 11) shock absorption, 12) waterproof, 13) appearance, and 14) weight. Conclusions Fostering trust through consistent and intuitive functions that can be used during various activities is perceived as highly important for satisfaction with prosthetic devices. Furthermore, expected long-term benefits associated with advanced devices are, alone, not sufficient motivation for their use. More intuitive triggering methods coupled with active assistance are necessary to make advanced solutions and their functions more accessible and beneficial. Finally, a multitude of individual characteristics and needs influence use and acceptance, highlighting the necessity of taking human factors into account in prosthetics. Clinical Relevance The results shed light on opportunities in future development of prosthetic knees and importance of human factors for powered prosthetic design. They further provide insight into aspects meaningful to highly active end users, affecting prosthetic use and satisfaction.

Autoencoder Composite Scoring to Evaluate Prosthetic Performance in Individuals with Lower Limb Amputation.

We created an overall assessment metric using a deep learning autoencoder to directly compare clinical outcomes in a comparison of lower limb amputees using two different prosthetic devices—a mechanical knee and a microprocessor-controlled knee. Eight clinical outcomes were distilled into a single metric using a seven-layer deep autoencoder, with the developed metric compared to similar results from principal component analysis (PCA). The proposed methods were used on data collected from ten participants with a dysvascular transfemoral amputation recruited for a prosthetics research study. This single summary metric permitted a cross-validated reconstruction of all eight scores, accounting for 83.29% of the variance. The derived score is also linked to the overall functional ability in this limited trial population, as improvements in each base clinical score led to increases in this developed metric. There was a highly significant increase in this autoencoder-based metric when the subjects used the microprocessor-controlled knee (p < 0.001, repeated measures ANOVA). A traditional PCA metric led to a similar interpretation but captured only 67.3% of the variance. The autoencoder composite score represents a single-valued, succinct summary that can be useful for the holistic assessment of highly variable, individual scores in limited clinical datasets.

A Primarily-Passive Knee Prosthesis with Powered Stance and Swing Assistance.

This paper describes a knee prosthesis that provides primarily-passive behavior akin to a state-of-the-art modulated passive microprocessor-controlled knee prosthesis (MPK), but also offers powered stance and swing assistance, which are layered on top of the passive functionality. The combination of both passive and powered behaviors is enabled by a unique electronically-selectable two-speed transmission, which enables the combination of very low output impedance and high resistive torques necessary for passive functionality, while also enabling the generative torque-speed characteristics suitable for stance and swing phase assistance. A control system is described that consolidates behaviors appropriate for a wide range of activities of daily living (ADLs) into six states, with each state providing adaptive torque behaviors appropriate for different phases of gait, whether powered or passive. Experimental results on an individual with transfemoral amputation suggest that the prosthesis and controller provide similar or improved passive behaviors relative to a commercially-available MPK, in addition to providing powered functionality commensurate with a powered prosthesis.

The Kenevo microprocessor-controlled prosthetic knee compared with non-microprocessor-controlled knees in individuals older than 65 years in Sweden: A cost-effectiveness and budget-impact analysis.

Background:Growing evidence suggests that individuals with transfemoral amputation or knee disarticulation using a prosthesis equipped with a microprocessor-controlled knee (MPK) benefit from enhanced mobility and safety, including less falls. In elderly individuals, high mortality rates are assumed to reduce the expected useful life of MPKs, and this raises concerns regarding their economic effectiveness.Objective:To investigate the cost-effectiveness and budget impact of the Kenevo/MPK (Ottobock, Germany) compared with non–microprocessor-controlled knees (NMPKs) in people older than 65 years at the time of transfemoral amputation/knee disarticulation, from a Swedish payer’s perspective.Methods:A decision-analytic model was developed to conduct the economic analysis of the Kenevo/MPK. Model parameters were derived from Swedish databases and published literature. Univariate and probabilistic sensitivity analyses were performed to explore parameter uncertainty.Results:Compared with NMPKs, the Kenevo/MPK reduced the frequency of hospitalizations by 137 per 1,000 person years while the frequency of fatal falls was reduced by 19 per 1,000 person-years in the simulation. Over a 25-year time horizon, the incremental cost-effectiveness ratio was EUR11,369 per quality-adjusted life year. The probability of the MPK being cost-effective at a threshold of EUR40,000 per quality-adjusted life year was 99%. The 5-year budget impact model predicted an increase in payer expenditure of EUR1.76 million if all new patients received a Kenevo/MPK, and 50% of current NMPK users switched to the MPK.Conclusions:Results of the modeling suggest that the Kenevo/MPK is likely to be cost-effective for elderly individuals, primarily because of a reduction in falls.

Degree of Safety Against Falls Provided by 4 Different Prosthetic Knee Types in People With Transfemoral Amputation: A Retrospective Observational Study

ObjectivePeople with transfemoral amputation have balance and mobility problems and are at high risk of falling. An adequate prosthetic prescription is essential to maximize their functional levels and enhance their quality of life. This study aimed to evaluate the degree of safety against falls offered by different prosthetic knees.MethodsA retrospective study was conducted using data from a center for prosthetic fitting and rehabilitation. Eligible individuals were adults with unilateral transfemoral amputation or knee disarticulation. The prosthetic knee models were grouped into 4 categories: locked knees, articulating mechanical knees (AMKs), fluid-controlled knees (FK), and microprocessor-controlled knees (MPK). The outcome was the number of falls experienced during inpatient rehabilitation while wearing the prosthesis. Association analyses were performed with mixed-effect Poisson models. Propensity score weighting was used to adjust causal estimates for participant confounding factors.ResultsData on 1486 hospitalizations of 815 individuals were analyzed. Most hospitalizations (77.4%) were related to individuals with amputation due to trauma. After propensity score weighting, the knee category was significantly associated with falls. People with FK had the highest rate of falling (incidence rate = 2.81 falls per 1000 patient days, 95% CI = 1.96 to 4.02). FK significantly increased the risk of falling compared with MPK (incidence rate ratio [IRRFK-MPK] = 2.44, 95% CI = 1.20 to 4.96). No other comparison among knee categories was significant.ConclusionsFluid-controlled prosthetic knees expose inpatients with transfemoral amputation to higher incidence of falling than MPK during rehabilitation training.ImpactThese findings can guide clinicians in the selection of safe prostheses and reduction of falls in people with transfemoral amputation during inpatient rehabilitation.

Survey of transfemoral amputee experience and priorities for the user-centered design of powered robotic transfemoral prostheses

BackgroundTransfemoral amputees experience a complex host of physical, psychological, and social challenges, compounded by the functional limitations of current transfemoral prostheses. However, the specific relationships between human factors and prosthesis design and performance characteristics have not yet been adequately investigated. The present study aims to address this knowledge gap.MethodsA comprehensive single-cohort survey of 114 unilateral transfemoral amputees addressed a broad range of demographic and clinical characteristics, functional autonomy, satisfaction and attitudes towards their current prostheses, and design priorities for an ideal transfemoral prosthesis, including the possibility of active assistance from a robotic knee unit. The survey was custom-developed based on several standard questionnaires used to assess motor abilities and autonomy in activities of daily living, prosthesis satisfaction, and quality of life in lower-limb amputees. Survey data were analyzed to compare the experience (including autonomy and satisfaction) and design priorities of users of transfemoral prostheses with versus without microprocessor-controlled knee units (MPKs and NMPKs, respectively), with a subsequent analyses of cross-category correlation, principal component analysis (PCA), cost-sensitivity segmentation, and unsupervised K-means clustering applied within the most cost-sensitive participants, to identify functional groupings of users with respect to their design priorities.ResultsThe cohort featured predominantly younger (< 50 years) traumatic male amputees with respect to the general transfemoral amputee population, with pronounced differences in age distribution and amputation etiology (traumatic vs. non-traumatic) between MPK and NMPK groups. These differences were further reflected in user experience, with MPK users reporting significantly greater overall functional autonomy, satisfaction, and sense of prosthesis ownership than those with NMPKs, in conjunction with a decreased incidence of instability and falls. Across all participants, the leading functional priorities for an ideal transfemoral prosthesis were overall stability, adaptability to variable walking velocity, and lifestyle-related functionality, while the highest-prioritized general characteristics were reliability, comfort, and weight, with highly variable prioritization of cost according to reimbursement status. PCA and user clustering analyses revealed the possibility for functionally relevant groupings of prosthesis features and users, based on their differential prioritization of these features—with implications towards prosthesis design tradeoffs.ConclusionsThis study’s findings support the understanding that when appropriately prescribed according to patient characteristics and needs in the context of a proactive rehabilitation program, advanced transfemoral prostheses promote patient mobility, autonomy, and overall health. Survey data indicate overall stability, modularity, and versatility as key design priorities for the continued development of transfemoral prosthesis technology. Finally, observed associations between prosthesis type, user experience, and attitudes concerning prosthesis ownership suggest both that prosthesis characteristics influence device acceptance and functional outcomes, and that psychosocial factors should be specifically and proactively addressed during the rehabilitation process.

Assessment of lower limb peripheral nerves with ultrasound in patients with traumatic amputation.

Objectives This study aims to assess the sciatic nerve (SN), common peroneal nerve (CPN), and tibial nerve (TN) by ultrasound in patients with traumatic lower limb amputation (LLA) and to examine the possible relationship between ultrasonographic and clinical findings. Patients and methods This cross-sectional study included a total of 33 male patients (mean age: 36.6±8.7 years; range, 21 to 48 years) who had LLA due to traumatic injury between May 2019 and April 2020. Amputation and prosthesis use and functional K level of activity were recorded. Ultrasound examinations were performed to measure the cross-sectional areas (CSAs) of the SN, CPN, and TN bilaterally at the same levels. The values from the normal sides were accepted as controls. Results The CSA values were greater on the amputated sides than the non-amputated sides for SN (p=0.001), TN (p=0.001), and CPN (p=0.015), regardless of the activity level. The amputated side SN (p=0.001), TN (p=0.001), and CPN (p=0.016) were thicker in patients with level of K4 activity than the non-amputated side. For the patients with K3 activity level, larger TN CSA values were determined on the amputated side, compared to those at the K4 level (p=0.035). The SN was found to be greater in patients using microprocessor-controlled knee prosthesis (p=0.032) and TN was larger in hypobaric sealing membrane users on the amputated sides (p=0.041). Conclusion The SN, CPN, and TN were found to be larger in all patients on the amputated sides and in patients with K4 activity level. Based on these findings, the K3 activity level and the use of hypobaric sealing membrane seems to affect the CSA values of TN. Additionally, the use of microprocessor knee prosthesis affects the CSA values of SN. We believe that these results may be essential for the analysis or prediction of lower extremity nerve involvement according to the K activity level and the use of prosthesis in patients with traumatic LLA.

Kinetic and Kinematics Parameters of Hip in Gait for a Congenital Longitudinal Tibial Deficiency with Orthoprosthesis and Transfemoral Prosthesis: A Case Study

ABSTRACT Introduction Congenital longitudinal tibial deficiency is a rare condition. It is characterized by partial or complete absence of tibia with a relatively intact fibula. Its standard treatment is surgery and employing orthoprosthesis or prosthesis. However, the effects of gaits according to the types of prosthesis is barely known. Methods Orthoprosthesis is offered to a 30-year-old man experiencing left-side congenital type 1 tibial hemimelia (classified as Jones type 1B) deficiency with thoracolumbar scoliosis and exhibiting a depressed shoulder as well as a stiff knee. He decided to have an amputation to wear a transfemoral (TF) prosthesis comprising a microprocessor-controlled knee. Results Three-dimensional gait analyses and a 6-minute walk test were performed preoperatively and postoperatively with the orthoprosthesis and TF prosthesis. Furthermore, the kinematics of hip flexion/extension and pelvic anterior/posterior tilt range of the motion degree were increased using TF prosthesis. The result of the kinetics of the hip flexion/extension moment and hip power parameters were affected using the TF prosthesis. Conclusions This case study suggests that the new prosthesis provides removable and adaptable component; further, it delivers a comfortable sitting experience because of its new socket design and knee joint flexion. Clinical Relevance Patient satisfaction is better with TF prosthesis than with orthoprosthesis. TF prosthesis is more cosmetic than orthoprosthesis, provides a symmetrical gait pattern, decreases donning and doffing durations, and there is no uncomfortable protrusion when sitting (due to amputation of the foot and leg part).

Evaluation of gait outcomes for individuals with established unilateral transfemoral amputation following the provision of microprocessor controlled knees in the context of a clinical service.

Microprocessor controlled knees (MPKs) have been shown to improve gait outcomes for individuals with unilateral transfemoral amputation (TFA); however, previous studies have limitations, which may affect their applicability. To compare gait outcomes between non-MPK and MPK conditions within a large and diverse cohort of established TFAs in the pragmatic context of an operational clinical service and to identify any demographic variables that correlate with changes in gait outcomes. This is a retrospective cohort study. Full-body three-dimensional motion capture and a portable breath gas analyser were used to evaluate gait-specific outcomes both pre-MPK and 6 months post-MPK provisions in TFAs (n = 32). The primary outcome measure was gait profile score, along with the following secondary outcome measures: walking velocity, step length, step length symmetry ratio, step time symmetry ratio, vertical ground reaction force symmetry index, base of support, center of mass deviation, and oxygen cost of walking. Data showed statistically significant improvement in gait profile score from 11.2° ± 2.2° to 10.1° ± 2.1° (p < 0.01) between non-MPK and MPK conditions. Other outcomes which showed significant improvement were walking velocity (p < 0.01), step length (p < 0.01), vertical ground reaction force symmetry index (p < 0.01), and center of mass deviation (p < 0.05). MPK provision offered significant gait improvements to this cohort of TFAs in an operational clinical setting. There still remains a large gap in gait outcomes between this cohort and those of healthy unimpaired adults. Improvements in socket design, prosthetic foot design, and physiotherapy intervention could further reduce this gap.

Using a microprocessor knee (C-Leg) with appropriate foot transitioned individuals with dysvascular transfemoral amputations to higher performance levels: a longitudinal randomized clinical trial

BackgroundIndividuals with transfemoral amputations who are considered to be limited community ambulators are classified as Medicare functional classification (MFCL) level K2. These individuals are usually prescribed a non-microprocessor controlled knee (NMPK) with an appropriate foot for simple walking functions. However, existing research suggests that these individuals can benefit from using a microprocessor controlled knee (MPK) and appropriate foot for their ambulation, but cannot obtain one due to insurance policy restrictions. With a steady increase in older adults with amputations due to vascular conditions, it is critical to evaluate whether advanced prostheses can provide better safety and performance capabilities to maintain and improve quality of life in individuals who are predominantly designated MFCL level K2. To decipher this we conducted a 13 month longitudinal clinical trial to determine the benefits of using a C-Leg and 1M10 foot in individuals at K2 level with transfemoral amputation due to vascular disease. This longitudinal clinical trial incorporated recommendations prescribed by the lower limb prosthesis workgroup to design a study that can add evidence to improve reimbursement policy through clinical outcomes using an MPK in K2 level individuals with transfemoral amputation who were using an NMPK for everyday use.MethodsTen individuals (mean age: 63 ± 9 years) with unilateral transfemoral amputation due to vascular conditions designated as MFCL K2 participated in this longitudinal crossover randomized clinical trial. Baseline outcomes were collected with their current prosthesis. Participants were then randomized to one of two groups, either an intervention with the MPK with a standardized 1M10 foot or their predicate NMPK with a standardized 1M10 foot. On completion of the first intervention, participants crossed over to the next group to complete the study. Each intervention lasted for 6 months (3 months of acclimation and 3 months of take-home trial to monitor home use). At the end of each intervention, clinical outcomes and self-reported outcomes were collected to compare with their baseline performance. A generalized linear model ANOVA was used to compare the performance of each intervention with respect to their own baseline.ResultsStatistically significant and clinically meaningful improvements were observed in gait performance, safety, and participant-reported measures when using the MPK C-Leg + 1M10 foot. Most participants were able to achieve higher clinical scores in gait speed, balance, self-reported mobility, and fall safety, while using the MPK + 1M10 combination. The improvement in scores were within range of scores achieved by individuals with K3 functional level as reported in previous studies.ConclusionsIndividuals with transfemoral amputation from dysvascular conditions designated MFCL level K2 benefited from using an MPK + appropriate foot. The inference and evidence from this longitudinal clinical trial will add to the knowledgebase related to reimbursement policy-making.Trial registration This study is registered on clinical trials.gov with the study title “Functional outcomes in dysvascular transfemoral amputees” and the associated ClinicalTrials.gov Identifier: NCT01537211. The trial was retroactively registered on February 7, 2012 after the first participant was enrolled.

Quality of life, body image, and mobility in lower-limb amputees using high-tech prostheses: A pragmatic trial.

High-tech prostheses are supposed to achieve better functional recovery over mechanical-controlled prostheses in lower-limb amputees. However, quantitative data are insufficient. We aimed to evaluate changes in quality of life, life satisfaction, perception of body image, and functional performance of lower-limb amputees when using a mechanical-controlled prosthesis versus a microprocessor-controlled knee (MPK) or transtibial vacuum-assisted suspension system (VASS) prosthesis. In this pragmatic study, 57 lower-limb amputees were assessed with the Satisfaction with the Prosthesis Questionnaire (SATPRO), revised Amputee Body Image Scale (ABIS-R), Trinity Amputation and Prosthesis Experience Scales (TAPES), Medical Outcomes Study Short Form-36 (SF-36) and 6-min walk test (6MWT). All assessments were performed under 2 conditions (i.e., using a mechanical-controlled prosthesis vs. an MPK/VASS prosthesis. Amputees who used an MPK/VASS prosthesis showed significant increases in all SF-36 subscale scores and all subscale scores of TAPES except adjustment to limitation (P=0.156). The amputees showed clinically relevant improvements in 6MWT (P<0.001) and in SATPRO and ABIS-R scores (P<0.001). Lower-limb amputees using an MPK/VASS prosthesis had better life satisfaction, quality of life and functional performance than those using a mechanical-controlled prosthesis.

Costs Associated with Lower- and Upper-Limb Amputation Over the First 4 Years with a Prosthesis

ABSTRACT Introduction The impact of amputation on health care costs is an understudied topic due to the lack of sufficient population size and data sources. The purpose of this investigation was to leverage a publicly available database on amputations to determine health care–associated costs for individuals with lower- and upper-limb amputation of varying limb loss levels during the first 4 years after receipt of their first prosthesis. Materials and Methods An insurance claims database was obtained via public records request from the Ohio Bureau of Workers' Compensation for persons who suffered a traumatic injury in the workplace that resulted in lower- or upper-limb amputation. Data included information on cost and frequency of prosthetic limbs, equipment, and appointments, as well as information on general hospital care, physical, vocational, and mental health therapies, prescription medication, and additional health care categories. The population was categorized into five limb loss levels: individuals with unilateral transfemoral and transtibial amputation, as well as individuals with hand, below-elbow, and above-elbow amputation. Prosthetic claim codes were examined to determine the types of prostheses prescribed over time based on Medicare guidelines for activity levels (K1–K4) for lower-limb devices and by type (passive [cosmetic], body-powered, hybrid, or externally powered) for upper-limb devices. These data were used to determine short-term costs over the first 4 years, depending on the initial prosthesis prescription. Differences between total costs per year and over all 4 years were explored within each population to determine how initial prosthetic prescription impacts cost. Results In general, the microprocessor-controlled devices (i.e., microprocessor-controlled knee prostheses or externally powered upper-limb prostheses) resulted in higher initial prosthetic and total hospital costs, whereas the simpler mechanical devices (i.e., non–microprocessor-controlled knee prostheses or passive/cosmetic upper-limb prostheses) resulted in lower costs. Costs were highest in prosthetics-related expenses and physical therapy, especially in groups with the more advanced prostheses, during the first year after prosthesis receipt; however, the differences in costs based on prosthesis type minimized as time increased and few cumulative cost differences were seen over 4 years. In addition to determining costs accrued over time, the database provided insight into how frequently individuals with amputation received a new prosthesis and at what level. The average number of devices per person per year averaged 0.62 ± 0.36 for individuals with transfemoral amputation, 0.78 ± 0.40 for individuals with transtibial amputation, 0.24 ± 0.18 for individuals with hand amputation, 0.45 ± 0.39 for individuals with below-elbow amputation, and 0.40 ± 0.32 for individuals with above-elbow amputation. Conclusions The results of this cost investigation provide new information regarding all aspects of health care for individuals with lower-limb amputation and upper-limb amputation, respectively, who suffer from occupation-related traumatic amputation. The results provide new data trends on prosthesis usage and highlight how prosthetic prescription may alter these costs. The results suggest that there are no statistical differences in cost outcomes after 4 years, indicating that paying more initially for a more advanced prosthesis does not result in higher initial costs over time than paying less initially for a simpler prosthesis.

Cost-effectiveness and budget impact of the microprocessor-controlled knee C-Leg in transfemoral amputees with and without diabetes mellitus

BackgroundThe safe use of a prosthesis in activities of daily living is key for transfemoral amputees. However, the number of falls varies significantly between different prosthetic device types. This study aims to compare medical and economic consequences of falls in transfemoral amputees who use the microprocessor-controlled knee joint C-Leg with patients who use non-microprocessor-controlled (mechanical) knee joints (NMPK). The main objectives of the analysis are to investigate the cost-effectiveness and budget impact of C-Legs in transfemoral amputees with diabetes mellitus (DM) and without DM in Germany.MethodsA decision-analytic model was developed that took into account the effects of prosthesis type on the risk of falling and fall-related medical events. Cost-effectiveness and budget impact analyses were performed separately for transfemoral amputees with and without DM. The study took the perspective of the statutory health insurance (SHI). Input parameters were derived from the published literature. Univariate and probabilistic sensitivity analyses (PSA) were performed to investigate the impact of changes in individual input parameter values on model outcomes and to explore parameter uncertainty.ResultsC-Legs reduced the rate of fall-related hospitalizations from 134 to 20 per 1000 person years (PY) in amputees without DM and from 146 to 23 per 1000 PY in amputees with DM. In addition, the C-Leg prevented 15 or 14 fall-related death per 1000 PY. Over a time horizon of 25 years, the incremental cost-effectiveness ratio (ICER) was 16,123 Euro per quality-adjusted life years gained (QALY) for amputees without DM and 20,332 Euro per QALY gained for amputees with DM. For the period of 2020–2024, the model predicted an increase in SHI expenditures of 98 Mio Euro (53 Mio Euro in prosthesis users without DM and 45 Mio Euro in prosthesis users with DM) when all new prosthesis users received C-Legs instead of NMPKs and 50% of NMPK user whose prosthesis wore out switched to C-Legs. Results of the PSA showed moderate uncertainty and a probability of 97–99% that C-Legs are cost-effective at an ICER threshold of 40,000 Euro (≈ German GDP per capita in 2018) per QALY gained.ConclusionResults of the study suggest that the C-Leg provides substantial additional health benefits compared with NMPKs and is likely to be cost-effective in transfemoral amputees with DM as well as in amputees without DM at an ICER threshold of 40,000 Euro per QALY gained.

Microprocessor-controlled knee joints in amputees worth its cost

Microprocessor-controlled knee joints in amputees worth its cost