Transtibial Prosthetic Socket Shape in a Developing Country: A study to compare initial outcomes in Pressure Cast hydrostatic and Patella Tendon Bearing designs

Six-minute walk test protocol variations in low-resource settings - A scoping review

BACKGROUND

The 6-min walk test (6MWT) is a validated tool, of submaximal intensity, used to objectively measure functional exercise capacity. In 2002, the American Thoracic Society (ATS) developed guidelines on standardising the implementation of the 6MWT. Despite the relative ease of conducting the 6MWT as per these guidelines, adaptations are implemented.

OBJECTIVES

Identify (1) what 6MWT adaptations to the ATS guidelines have been described in low-resource settings (LRS), (2) the purpose of the adapted 6MWT and (3) the reported argumentation for making these adaptations in relation to the specific context.

METHODS

Five databases were searched from inception until February 2021. Studies that adapted and conducted the 6MWT in LRS were included. Data concerning the study source, participants, 6MWT: purpose, variations, outcome and rationale were extracted.

RESULTS

A total of 24 studies were included. The majority of studies (n = 18; 75%) were conducted in lower-middle income countries. The most common adaptation implemented was variation to course length. Eight studies provided a rationale for adapting the 6MWT. Space constraint was the most common reason for adaptation.

CONCLUSION

The most common reason (space constraints) for adapting the 6MWT in LRS was addressed through adaptations in course length and/or configuration. The results of this review suggest that the value of the ATS-guided 6MWT in LRS may need to be re-evaluated.

CLINICAL IMPLICATIONS

Using adapted forms of the 6MWT may lead to an underestimation of a patient's abilities, misinformed discharge and developing inappropriate exercise programmes. Additionally, diverting from ATS guidelines may affect the continuity of care.

Pioneering low-cost 3D-printed transtibial prosthetics to serve a rural population in Sierra Leone - an observational cohort study

BACKGROUND

There is a huge unmet global need for affordable prostheses. Amputations often happen in Sierra Leone due to serious infections, complex wounds, traffic accidents and delayed patient presentation to the hospital. However, purchasing a prosthesis is still beyond reach for most Sierra Leonean amputees.

METHOD

We applied computer-aided design (CAD) and computer-aided manufacturing (CAM) to produce low-cost transtibial prosthetic sockets. In February and March 2020, eight participants received a 3D printed transtibial prosthesis in the village of Masanga in Tonkolili district, Sierra Leone. Research was performed using questionnaires to investigate the use, participants' satisfaction, and possible complications related to the prostheses. Questionnaires were conducted prior to production of the prosthesis and five to six weeks after fitting the prosthesis. A personal short-term goal was set by the participants.

FINDINGS

Competitively priced and fully functional prostheses were produced locally. After six weeks, all participants were still wearing the prosthesis and six of the eight participants reached their personal rehabilitation goals. Using their prostheses, all participants were no longer in need of their crutches.

INTERPRETATION

We have come a step closer to the production of low-cost prostheses for low-and middle-income countries (LMICs). The goal of our project is to perform long-term follow-up and to refine our concept of 3D printed prostheses for LMICs to provide practical solutions for a global health need unmet to date.

FUNDING

€ 15,000 was collected during a crowdfunding campaign in collaboration with the Dutch Albert Schweitzer Fund. Internship allowance for MvdS was obtained from the University of Twente. 3D-scanner, 3D-printer, and printing material were donated by Ultimaker BV and Shining 3D.

An Investigation of Pressure Profiles and Wearer Comfort During Walking With a Transtibial Hydrocast Socket

OBJECTIVE

The aims of the study were to conduct an investigation of the transtibial hydrocast socket interface pressures during walking and to explore potential relationships between pressures experienced and resultant wearer comfort.

DESIGN

In this cross-sectional study, pressure data at the limb and hydrocast socket interface during walking were collected from 16 users of hydrocast sockets. The pressures at this interface were described by location, magnitude, and duration for all participants and were compared between the most and least comfortable participants.

RESULTS

High pressures were found about the bony prominences of the residual limb, especially the tibial crest of the anterior distal region. Factors identified as potentially causing discomfort (P < 0.1, d > 0.80) were high peak pressures at the anterior proximal region and longer durations of submaximal loading at the lateral proximal region and the anterior and medial distal regions. High pressure variability at the anterior proximal region may also contribute to discomfort (P = 0.106, d = 0.88).

CONCLUSIONS

The hydrocast socket interface pressures have been described for a cohort of users. A number of differences were found in the pressure profiles of the most and least comfortable participants. These differences suggest trends between the identified pressure parameters and resultant wearer comfort. Future studies should confirm these exploratory results.

Predictive prosthetic socket design: part 2-generating person-specific candidate designs using multi-objective genetic algorithms

In post-amputation rehabilitation, a common goal is to return to ambulation using a prosthetic limb, suspended by a customised socket. Prosthetic socket design aims to optimise load transfer between the residual limb and mechanical limb, by customisation to the user. This is a time-consuming process, and with the increase in people requiring these prosthetics, it is vital that these personalised devices can be produced rapidly while maintaining excellent fit, to maximise function and comfort. Prosthetic sockets are designed by capturing the residual limb’s shape and applying a series of geometrical modifications, called rectifications. Expert knowledge is required to achieve a comfortable fit in this iterative process. A variety of rectifications can be made, grouped into established strategies [e.g. in transtibial sockets: patellar tendon bearing (PTB) and total surface bearing (TSB)], creating a complex design space. To date, adoption of advanced engineering solutions to support fitting has been limited. One method is numerical optimisation, which allows the designer a number of likely candidate solutions to start the design process. Numerical optimisation is commonly used in many industries but not prevalent in the design of prosthetic sockets. This paper therefore presents candidate shape optimisation methods which might benefit the prosthetist and the limb user, by blending the state of the art from prosthetic mechanical design, surrogate modelling and evolutionary computation. The result of the analysis is a series of prosthetic socket designs that preferentially load and unload the pressure tolerant and intolerant regions of the residual limb. This spectrum is bounded by the general forms of the PTB and TSB designs, with a series of variations in between that represent a compromise between these accepted approaches. This results in a difference in pressure of up to 31 kPa over the fibula head and 14 kPa over the residuum tip. The presented methods would allow a trained prosthetist to rapidly assess these likely candidates and then to make final detailed modifications and fine-tuning. Importantly, insights gained about the design should be seen as a compliment, not a replacement, for the prosthetist’s skill and experience. We propose instead that this method might reduce the time spent on the early stages of socket design and allow prosthetists to focus on the most skilled and creative tasks of fine-tuning the design, in face-to-face consultation with their client.

Influences and trends of various shape-capture methods on outcomes in trans-tibial prosthetics: A systematic review

INTRODUCTION

In trans-tibial prosthetics, shape-capture methods are employed to create a representation of the residuum. Shape-capture methods can be grouped into the categories of 'hands-on', 'hands-off' and computer-aided design.

OBJECTIVE

This review examines the influences and trends of shape-capture methods on the outcomes of quality, comfort of user and clinical efficiency, in the population of trans-tibial prosthesis users.

STUDY DESIGN

Systematic Review.

METHOD

Databases and relevant journals were searched. Participants included trans-tibial prosthetics users/limb models. Interventions included shape-capture methods. Outcomes included quality, comfort of user and clinical efficiency.

RESULTS

Overall, 22 papers were evaluated; 8 papers evaluated hands-on and hands-off methods, 2 evaluated computer-aided design and 12 evaluated measurement systems used with shape capture. No papers relating to clinical efficiency were found.

CONCLUSION

Overall evidence was weak in suggesting that effects on outcomes were due to the sole influences of shape capture. However, studies suggest that hands-on methods are dependent on a prosthetist's skill. Hands-off methods, although repeatable, might still require experience to attain a good fit. Computer-aided design studies were mostly done on theoretical models. Shape-capture measurements require more consistent 'gold standards'. The relation between socket fit and comfort is still unclear. Overall, more research is required in each area.

CLINICAL RELEVANCE

A good fitting prosthetic socket is crucial for efficient and comfortable use of a prosthesis. To attain the best chances of a good fit, it is important that the characteristics of the residuum are captured as accurately as possible during the initial "shape capture" stage. This paper attempts to categorize and evaluate the existing shape capture methods on their influence and trends on various outcomes - Quality of shape capture, comfort of user and clinical efficiency.

The functional, spatio-temporal and satisfaction outcomes of transtibial amputees with a hydrocast socket following an extended usage period in an under-resourced environment

BACKGROUND

Transtibial hydrocast sockets have been shown to be a potential alternative to hand-cast patella-tendon bearing sockets, the use of which would have particular benefits in under-resourced environments. However, data concerning wearer outcomes of hard hydrocast sockets (i.e. those without silicone liners), especially over long-term usage periods, is scarce in the literature.

RESEARCH QUESTIONS

Are there any changes in wearer functional, spatio-temporal or satisfaction outcomes over a long usage period with a hydrocast socket? And how do the post-usage period outcomes compare with those from the wearers original prostheses?

METHODS

In this pre-post interventional study, the clinical outcomes of twenty-one experienced transtibial prostheses users were evaluated using widely-accepted and employed methods to assess wearer functional capacity, mobility, gait and satisfaction. The participants were fit with a hard hydrocast socket and the outcomes after an extensive usage period of 5 months were compared to the pre-usage period data following initial fitting and the data collected from the participants' original prosthetic limb.

RESULTS

Significant differences were found in the temporal parameters of gait, all indicating decreased reliance on the intact limb and an increased loading of the prosthetic limb with the post-usage period hydrocast socket compared to both the pre-usage period socket and the participants' original limbs. No differences in the functional capacity, mobility, spatial gait parameters or satisfaction were found between the socket conditions.

SIGNIFICANCE

This is the largest study to date of functional, spatio-temporal and satisfaction outcomes of hydrocast sockets following an extended usage period in an under-resourced environment.