Improvement in walking abilities in transfemoral amputees with a distal weight bearing implant

Prosthetic Limb Attachment via Electromagnetic Attraction Through a Closed Skin Envelope

OBJECTIVE

Current socket-based methods of prosthetic limb attachment are responsible for many of the dominant problems reported by persons with amputation. In this work, we introduce a new paradigm for attachment via electromagnetic attraction between a bone-anchored ferromagnetic implant and an external electromagnet. Our objective was to develop a design framework for electromagnetic attachment, and to evaluate this framework in the context of transfemoral amputation.

METHODS

We first used inverse dynamics to calculate the forces required to suspend a knee-ankle-foot prosthesis during gait. We then conducted cadaveric dissections to inform implant geometry and design a surgical methodology for covering the implant. We also developed an in silico framework to investigate how electromagnet design affects system performance. Simulations were validated against benchtop testing of a custom-built electromagnet.

RESULTS

The physical electromagnet matched simulations, with a root-mean-square percentage error of 4.2% between measured and predicted forces. Using this electromagnet, we estimate that suspension of a prosthesis during gait would require 33 W of average power. After 200 and 1000 steps of simulated walking, the temperature at the skin would increase 2.3 °C and 15.4 °C relative to ambient, respectively.

CONCLUSION

Our design framework produced an implant and electromagnet that could feasibly suspend a knee-ankle-foot prosthesis during short walking bouts. Future work will focus on optimization of this system to reduce heating during longer bouts.

SIGNIFICANCE

This work demonstrates the initial feasibility of an electromagnetic prosthetic attachment paradigm that has the potential to increase comfort and improve residual limb health for persons with amputation.

Loading characteristics data applied on osseointegrated implant by transfemoral bone-anchored prostheses fitted with state-of-the-art components during daily activities

The data in this paper are related to the research article entitled “Load applied on osseointegrated implant by transfemoral bone-anchored prostheses fitted with state-of-the-art prosthetic components” (Frossard et al. Clinical Biomechanics, 89 (2021) 105457. DOI: 10.1016/j.clinbiomech.2021.105457). This article contains the overall and individual loading characteristics applied on transfemoral press-fit osseointegrated implant generated by bone-anchored prostheses fitted with state-of-the-art components during daily activities (i.e., microprocessor-controlled Rheo Knee XC knee, energy-storing-and-returning Pro-Flex XC or LP feet (ÖSSUR, Iceland)). Confounders of the loads are presented. The load profiles are characterized by the loading patterns, loading boundaries and loading local extrema of the forces and moments applied during straight-level walking, ascending and descending ramp and stairs at self-selected comfortable pace. The confounders of the loading information as well as new insights into inter-participants variability of loading patterns, loading boundaries and loading local extrema can inform the design of subsequent cross-sectional and longitudinal studies as well as literature reviews and meta-analyzes. The loading datasets are critical to clinicians and engineers designing finite element models of osseointegrated implants (e.g., medullar and percutaneous parts) and prosthetic components, algorithms capable to recognize the loading patterns applied on a residuum during daily activities, as well as clinical trials assessing the effects of particular prosthetic care interventions. Altogether, these datasets provide promoters of prosthetic care innovations with valuable insights informing the prescription of advanced prosthetic components to the growing population of individuals suffering from lower limb loss choosing bionics solutions. Online repository contains the files: https://data.mendeley.com/datasets/gmsyv97cpc/1

Functional outcomes and user preferences of individuals with transfemoral amputations using two types of knee joints in under-resourced settings

BACKGROUND

Information relating to prosthetic performance can inform clinical practice and improve patient outcomes in under-resourced countries.

OBJECTIVES

The main goal of this study was to compare functional outcomes and user preferences of individuals with transfemoral amputations using common types of knee joints in an under-resourced country.

STUDY DESIGN

Prospective, longitudinal, before and after trial.

METHODS

Twenty individuals with unilateral transfemoral amputations from a center in Cambodia transitioned from a commonly used single-axis manually locking knee International Committee of the Red Cross (ICRC) to a more advanced multiaxis knee joint with stance control All-Terrain Knee (ATK). Data were collected for the ICRC knee joint and the ATK immediately after fitting, after acclimation, and as part of a long-term follow-up. A timed walk test assessed walking distance and efficiency. Mobility and user-preferences were evaluated through questionnaires.

RESULTS

Distance during the timed walk test was significantly higher for the ATK compared with ICRC (P < 0.001), with functional gains retained at follow-up. No differences were found for gait efficiency and the mobility questionnaires. All participants, except one, preferred the ATK prosthesis. Benefits included greater knee stability and fewer perceived knee collapses; however, some disliked the appearance of the ATK.

CONCLUSIONS

The findings suggest positive outcomes with prosthetic services in under-resourced regions and the ICRC system, as well as the potential for improved functional outcomes with more advanced multiaxis knee components.

Impact of prostheses on quality of life and functional status of transfemoral amputees in Tanzania

Background

The rise of diabetes and traumatic injury has increased limb loss-related morbidity in low- and middle-income countries (LMICs). Despite this, the majority of amputees in LMICs have no access to prosthetic devices, and the magnitude of prosthesis impact on quality of life (QOL ) and function has not been quantified.

Objectives

Quantify the impact of prostheses on QOL and function in Tanzanian transfemoral amputees.

Method

A prospective cohort study was conducted. Transfemoral amputees at Muhimbili Orthopaedic Institute were assessed twice before and three times after prosthetic fitting using EuroQol-5D-3L (EQ-5D-3L), Prosthetic Limb Users Survey of Mobility (PLUS-M), 2-minute walk test (2MWT) and Physiologic Cost Index (PCI). Data were analysed for change over time. Subgroup analysis was performed for amputation aetiology (vascular or non-vascular) and prosthesis use.

Results

Amongst 30 patients, EQ-5D, PLUS-M and 2MWT improved after prosthesis provision (p < 0.001). EuroQol-5D increased from 0.48 to 0.85 at 1 year (p < 0.001). EuroQol-5D and 2MWT were higher in non-vascular subgroup (p < 0.030). At 1-year, 84% of non-vascular and 44% of vascular subgroups reported using their prosthesis (p = 0.068).

Conclusion

Prosthesis provision to transfemoral amputees in an LMIC improved QOL and function. This benefit was greater for non-vascular amputation aetiologies. Quality of life and function returned to pre-prosthesis levels with discontinued use of prosthesis.

A Preliminary Cost-Utility Analysis of the Prosthetic Care Innovations: Case of the Keep Walking Implant

Several obstacles must be overcome before preliminary cost-utility analyses (CUA) of prosthetic care innovations can be routinely performed. The basic framework of preliminary CUAs and hands- on recommendations suggested previously might contribute to wider adoption. However, a practical application for an emerging intervention is needed to showcase the capacity of this proposed preliminary CUA framework. This study presented the outcomes of preliminary CUA of the distal weight bearing Keep Walking Implant (KWI), an emerging prosthetic care innovation that may reduce socket fittings for individuals with transfemoral amputation. The preliminary CUAs compared the provision of prosthetic care without (usual intervention) and with the KWI (new intervention) using a 15-step iterative process focused on feasibility, constructs, analysis, and interpretations of outcomes from an Australia government prosthetic care perspective over a six-year time horizon. Baseline and incremental costs were extracted from schedules of allowable expenses. Baseline utilities were extracted from a study and converted into quality-adjusted life-year (QALY). Incremental utilities were calculated based on sensible gains of QALY from baselines. The provision of the prosthetic care with the KWI could generate an indicative incremental cost-utility ratio (ICUR) of -$36,890 per QALY, which was $76,890 per QALY below willingness-to-pay threshold, provided that the KWI reduces costs by $17,910 while increasing utility by 0.485 QALY compared to usual interventions. This preliminary CUA provided administrators of healthcare organizations in Australia and elsewhere with prerequisite evidence justifying further access to market and clinical introduction of the KWI. Altogether, this work suggests that the basic framework of the preliminary CUA of a prosthetic care innovation proposed previously is feasible and informative when a series of assumptions are carefully considered. This study further confirms that preliminary CUAs prosthetic care interventions might be a relevant alternative to full CUA for other medical treatments.

Lower limb prosthetic interfaces: Clinical and technological advancement and potential future direction

The human-prosthesis interface is one of the most complicated challenges facing the field of prosthetics, despite substantive investments in research and development by researchers and clinicians around the world. The journal of the International Society for Prosthetics and Orthotics, Prosthetics and Orthotics International, has contributed substantively to the growing body of knowledge on this topic. In celebrating the 50th anniversary of the International Society for Prosthetics and Orthotics, this narrative review aims to explore how human-prosthesis interfaces have changed over the last five decades; how research has contributed to an understanding of interface mechanics; how clinical practice has been informed as a result; and what might be potential future directions. Studies reporting on comparison, design, manufacturing and evaluation of lower limb prosthetic sockets, and osseointegration were considered. This review demonstrates that, over the last 50 years, clinical research has improved our understanding of socket designs and their effects; however, high-quality research is still needed. In particular, there have been advances in the development of volume and thermal control mechanisms with a few designs having the potential for clinical application. Similarly, advances in sensing technology, soft tissue quantification techniques, computing technology, and additive manufacturing are moving towards enabling automated, data-driven manufacturing of sockets. In people who are unable to use a prosthetic socket, osseointegration provides a functional solution not available 50 years ago. Furthermore, osseointegration has the potential to facilitate neuromuscular integration. Despite these advances, further improvement in mechanical features of implants, and infection control and prevention are needed.

Advanced techniques in amputation surgery and prosthetic technology in the lower extremity

Bone-anchored implants give patients with unmanageable stump problems hope for drastic improvements in function and quality of life and are therefore increasingly considered a viable solution for lower-limb amputees and their orthopaedic surgeons, despite high infection rates.Regarding diversity and increasing numbers of implants worldwide, efforts are to be supported to arrange an international bone-anchored implant register to transparently overview pros and cons.Due to few, but high-quality, articles about the beneficial effects of targeted muscle innervation (TMR) and regenerative peripheral nerve interface (RPNI), these surgical techniques ought to be directly transferred into clinical protocols, observations and routines.Bionics of the lower extremity is an emerging cutting-edge technology. The main goal lies in the reduction of recognition and classification errors in changes of ambulant modes. Agonist-antagonist myoneuronal interfaces may be a most promising start in controlling of actively powered ankle joints.As advanced amputation surgical techniques are becoming part of clinical routine, the development of financing strategies besides medical strategies ought to be boosted, leading to cutting-edge technology at an affordable price.Microprocessor-controlled components are broadly available, and amputees do see benefits. Devices from different manufacturers differ in gait kinematics with huge inter-individual varieties between amputees that cannot be explained by age. Active microprocessor-controlled knees/ankles (A-MPK/As) might succeed in uneven ground-walking. Patients ought to be supported to receive appropriate prosthetic components to reach their everyday goals in a desirable way.Increased funding of research in the field of prosthetic technology could enhance more high-quality research in order to generate a high level of evidence and to identify individuals who can profit most from microprocessor-controlled prosthetic components. Cite this article: EFORT Open Rev 2020;5:724-741. DOI: 10.1302/2058-5241.5.190070.

Micromotion and Push-Out Evaluation of an Additive Manufactured Implant for Above-the-Knee Amputees

In comparison to through-knee amputees the outcomes for above-the-knee amputees are relatively poor; based on this novel techniques have been developed. Most current percutaneous implant-based solutions for transfemoral amputees make use of high stiffness intramedullary rods for skeletal fixation, which can have risks including infection, femoral fractures, and bone resorption due to stress shielding. This work details the cadaveric testing of a short, cortical bone stiffness-matched subcutaneous implant, produced using additive manufacture, to determine bone implant micromotion and push-out load. The results for the micromotions were all <20 μm and the mean push-out load was 2,099 Newtons. In comparison to a solid control, the stiffness-matched implant exhibited significantly higher micromotion distributions and no significant difference in terms of push-out load. These results suggest that, for the stiffness-matched implant at time zero, osseointegration would be facilitated and that the implant would be securely anchored. For these metrics, this provides justification for the use of a short-stem implant for transfemoral amputees in this subcutaneous application. © 2019 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 37:2104-2111, 2019.

Metabolic costs of activities of daily living in persons with a lower limb amputation: A systematic review and meta-analysis

Objective

To systematically review the literature on the metabolic costs of activities of daily living (ADL) in persons with a lower limb amputation (LLA).

Data sources

A literature search was undertaken in the Pubmed, Embase, CINAHL, CENTRAL, and PsycINFO databases using keywords and synonyms for LLA, metabolic costs, and ADL. The last search was performed on November 29^th, 2017.

Study selection

Studies were included if they met the following 2 criteria: participants were adults with a (unilateral or bilateral) LLA and metabolic costs were measured while participants performed a physical activity or ADL.

Data extraction and synthesis

Data of 1,912 participants from 61 studies were included in the systematic review and meta-analysis. The studies used different terms to describe metabolic costs. Participants were recruited in different settings, relatively healthy, with few comorbidities. Limited data were available on metabolic costs of other activities than walking with a prosthesis. A linear mixed model analysis was performed based on the means reported, with study as unit of analysis and test results of different groups and measurement conditions as repeated measures within the unit of analysis. Predictors entered in the analysis were e.g. level and reason of amputation, age, weight, and height. During walking, oxygen consumption (ml O₂/kg/min) and heart rate (beats/min) increased with a higher walking speed and a more proximal amputation. Additionally, oxygen consumption was determined by the interaction terms walking speed x amputation level and walking speed squared. Heart rate was determined by the interaction term walking speed squared.

Conclusion

During walking, oxygen consumption (ml O₂/kg/min) and heart rate (beats/min) increased with a higher walking speed and a more proximal amputation. Data on metabolic costs of other activities were limited. The poor quality of the studies and the relatively healthy participants limited generalizability of the results of the meta-analysis.

Distance and speed of walking in individuals with trans-femoral amputation fitted with a distal weight-bearing implant

INTRODUCTION

Preservation of femoral condyles in patients with knee disarticulation amputation (KDA) facilitates distal support inside the socket, compared to trans-femoral amputation (TFA), and allows the direct transfer of weight-bearing loads toward residual limbs.

HYPOTHESIS

The hypothesis was that the gait distance and speed of TFA patients after a surgical femoral implant that allowed the distal support of the residuum would improve.

MATERIAL AND METHODS

Twenty-three TFA patients received a titanium implant that allowed the distal weight bearing of the residuum inside the socket. The post-intervention follow-up period lasted 14 months. Gait distance and speed were assessed with the 2-minute walk test (2MWT).

RESULTS

The amputation etiology was trauma in 11 patients (48%), peripheral vascular disease in nine (39%) and oncologic disease in three (13%). The mean 2MWT distance was 103.6±34.7m prior to femoral implant and 128±38.9m at 14 months, which implies an improvement of 24% (p<0.001). The mean gait speed was 0.86±0.29m/s prior to femoral implant and 1.06±0.32m/s at 14 months (p<0.001).

DISCUSSION

After implant placement, distance covered increased by 24%. This value is higher than those described by other groups, such as Rau (12.6%) and Darter (19.2%), who assessed improvement in distance covered with the 2MWT in a younger population and after completing different physiotherapy programs. Our results showed improved distance walked and gait speed as well as in the physical functioning score in TFA patients 14 months after receiving a femoral implant that permitted distal residuum loading.

TYPE OF STUDY

An experimental prospective study.

LEVEL OF PROOF

III, case-control study.

Load characteristics following transfemoral amputation in individuals fitted with bone-anchored prostheses: a scoping review protocol

REVIEW QUESTION

The main purpose of this scoping review is to characterize loading information applied on the residuum of individuals with transfemoral amputation fitted with an osseointegrated fixation for bone-anchored prostheses.The objectives of this scoping review are: i) to map the scope of loading variables, and ii) to report the range of magnitude of loads that has been directly measured using a portable kinetic recording apparatus fitted at the distal end of the residuum during rehabilitation exercises, standardized and unscripted activities of daily living, and adverse events.The specific review questions are.

Effect of a distal weight-bearing implant on visual analog scale scores in 23 transfemoral amputees

The objective of this interrupted time series clinical trial was to evaluate the effect of a distal weight-bearing implant on well-being in patients with transfemoral amputations using the visual analog scale (VAS). A total of 29 patients from five hospitals with previous transfemoral amputations were surgically implanted with an osseoanchored implant with a distal spacer that allows a direct load on the residuum over the distal surface of the socket. Patients were followed for a 14-month period and assessed presurgically and postsurgically using the VAS. The Wilcoxon test was used to evaluate the differences between variables. VAS mean scores improved significantly after intervention. Significant and clinically meaningful improvements in the VAS score suggest overall improvement in well-being for patients after receiving a distal weight-bearing implant.

Cost-effectiveness of bone-anchored prostheses using osseointegrated fixation: Myth or reality?

BACKGROUND

In principle, lower limb bone-anchored prostheses could alleviate expenditure associated with typical socket manufacturing and residuum treatments due to socket-suspended prostheses.

OBJECTIVE

This study reports (a) the incremental costs and (b) heath gain as well as (c) cost-effectiveness of bone-anchored prostheses compared to socket-suspended prostheses.

STUDY DESIGN

Retrospective individual case-controlled observations and systematic review.

METHODS

Actual costs were extracted from financial records and completed by typical costs when needed over 6-year time horizon for a cohort of 16 individuals. Health gains corresponding to quality-adjusted life-year were calculated using health-related quality-of-life data presented in the literature.

RESULTS

The provision of bone-anchored prostheses costed 21% ± 41% more but increased quality-adjusted life-years by 17% ± 5% compared to socket-suspended prostheses. The incremental cost-effectiveness ratio ranged between -$25,700 per quality-adjusted life-year and $53,500 per quality-adjusted life-year with indicative incremental cost-effectiveness ratio of approximately $17,000 per quality-adjusted life-year. Bone-anchored prosthesis was cost-saving and cost-effective for 19% and 88% of the participants, respectively.

CONCLUSION

This study indicated that bone-anchored prostheses might be an acceptable alternative to socket-suspended prostheses at least from a prosthetic care perspective in Australian context. Altogether, this initial evidence-based economic evaluation provided a working approach for decision makers responsible for policies around care of individuals with lower limb amputation worldwide. Clinical relevance For the first time, this study provided evidence-based health economic benefits of lower limb bone-anchored prostheses compared to typical socket-suspended prostheses from a prosthetic care perspective that is essential to clinicians and decision makers responsible for policies.

Biomechanical Characterisation of Bone-anchored Implant Systems for Amputation Limb Prostheses: A Systematic Review

Bone-anchored limb prostheses allow for the direct transfer of external loads from the prosthesis to the skeleton, eliminating the need for a socket and the associated problems of poor fit, discomfort, and limited range of movement. A percutaneous implant system for direct skeletal attachment of an external limb must provide a long-term, mechanically stable interface to the bone, along with an infection barrier to the external environment. In addition, the mechanical integrity of the implant system and bone must be preserved despite constant stresses induced by the limb prosthesis. Three different percutaneous implant systems for direct skeletal attachment of external limb prostheses are currently clinically available and a few others are under investigation in human subjects. These systems employ different strategies and have undergone design changes with a view to fulfilling the aforementioned requirements. This review summarises such strategies and design changes, providing an overview of the biomechanical characteristics of current percutaneous implant systems for direct skeletal attachment of amputation limb prostheses.

Development of a Procedure for the Government Provision of Bone-Anchored Prosthesis Using Osseointegration in Australia

BACKGROUND

Governmental organizations are facing challenges in adjusting procedures providing equitable assistance to consumers with amputation choosing newly available osseointegrated fixations for bone-anchored prostheses (BAPs) over socket-suspended prostheses.

OBJECTIVES

The aims of this study were to (1) present a procedure focusing on tasks, documents and costs of prosthetic care, and (2) share observed obstacles and facilitators to implementation.

METHODS

This research aimed at developing a governmental procedure for the provision of BAPs was designed as an action research study. A total of 18 individuals with transfemoral amputation solely funded by a Queensland State organization were considered.

RESULTS

The procedure, developed between January 2011 and June 2015, included seven processes involving fixed expenses during treatment and five processes regulating ongoing prosthetic care expenses. Prosthetic care required 22 h of labor, corresponding to AUD$3300 per patient, during rehabilitation. Prosthetists spend 64 and 36% of their time focusing on prosthetic care and other activities, respectively. The procedure required adjustments related to the scope of practice of prosthetists, funding of prosthetic limbs during rehabilitation, and allocation of microprocessor-controlled prosthetic knees. Approximately 41% (7) and 59% (10) of obstacles were within (e.g. streamlining systematic processes, sustaining evaluation of this complex procedure) or outside (e.g. early and consistent consultations of stakeholders, lack of a definitive rehabilitation program) governmental control, respectively, and approximately 89% (17) of the facilitators were within governmental control (e.g. adapting existing processes).

CONCLUSION

This study provides a working plan to stakeholders developing and implementing policies around the care of individuals choosing osseointegration for BAPs.