User perspectives of digital manufacturing for lower-limb prosthetic sockets.

BACKGROUND: There is growing interest to use digital technology (DT) for manufacturing lower-limb prosthetic sockets to improve efficiency and clinical outcomes. However, little is known about how lower-limb prosthesis users perceive DTs, such as 3D scanning and 3D printing. OBJECTIVES: This study aimed to provide an understanding of perceptions and experiences with DT for prosthetic socket manufacturing from the perspective of prosthesis users. STUDY DESIGN: A qualitative descriptive research study. METHODS: Nine lower-limb prosthesis users (mean age 56; 5 female; 4 male) participated in one-on-one semistructured telephone interviews. Inductive thematic analysis was performed to identify a codebook and emerging themes from the interview transcripts. RESULTS: Two major themes were identified: (1) expectations and prioritization of 3D printed socket usability and (2) facilitators and barriers to uptake of DT among patients. CONCLUSION: DT methods were found to be acceptable and feasible from a patient perspective, although technological advancements are still required, and real-time communication about the process may be vital for ensuring patient engagement. Consideration of these findings may improve patient satisfaction to emerging prosthesis treatment plans and ultimately support widespread adoption of DT as an additional tool for fabricating prosthetic sockets.

Business practices efficiency: Impact of integrating digital technology on clinical P&O practices.

Additive manufacturing (AM) is on the path to transforming the approach to Prosthetics and Orthotics (P&O) manufacturing. Although digitalization of limbs and other body parts is not new to the field, it has not been widely accepted by the industry for various reasons. However, the reliability and precision that AM can attain, and the availability of various materials is improving rapidly. This professional opinion article discusses the ways that AM has changed P&O services, with a specific focus on prosthetic socket manufacturing. Digitalizing P&O services will eventually change the business model used in clinics, which is further explored here.

Evaluation of an instrument-assisted dynamic prosthetic alignment technique for individuals with transtibial amputation.

BACKGROUND: A prosthesis that is not optimally aligned can adversely influence the rehabilitation and health of the amputee. Very few studies to date evaluate the effectiveness and utility of instrument-assisted alignment techniques in clinical practice. OBJECTIVES: To compare an instrument-assisted dynamic alignment technique (Compas(™)) to conventional methods. STUDY DESIGN: In a crossover study design, dynamic prosthetic alignments were provided to nine individuals with unilateral transtibial amputations to compare conventional and instrument-assisted alignment techniques. METHODS: The instrument-assisted technique involved a commercially available force and torque sensing dynamic alignment system (Compas). Cadence, pelvic accelerations, and socket moments were assessed. A custom questionnaire was used to gather user perceptions. RESULTS: No differences between alignment techniques were found in global gait measures including cadence and pelvic accelerations. No significant alignment differences were achieved by examination of angular changes between the socket and foot; however, significantly higher below-the-socket moments were found with the instrument-assisted technique. From the questionnaire, six amputees had no preference, while three preferred the conventional alignment. CONCLUSION: The use of Compas appears to produce similar alignment results as conventional techniques, although with slightly higher moments at the socket. CLINICAL RELEVANCE: This study provides new information about the clinical utilization of instrument-assisted prosthetic alignment techniques for individuals with transtibial amputation.

Mobility function of a prosthetic knee joint with an automatic stance phase lock.

BACKGROUND: There is a need for a prosthetic knee joint design that is technologically and functionally appropriate for use in developing countries. OBJECTIVES: To develop and clinically evaluate a new type of stance phase controlled prosthetic knee joint that provides stance phase stability without inhibiting swing phase flexion. STUDY DESIGN: A crossover repeated measures study design comparing the new knee joint to the participant's conventional low- or high-end prosthetic knee joint. METHODS: The new knee joint was fitted to fourteen individuals aged 15 to 67 years with unilateral lower limb amputations. Walk tests were performed to measure walking speed. Energy expenditure was estimated using the physiological cost index (PCI). RESULTS: Walking speeds with the new knee joint were on average 0.14 m/s faster than conventional low-end knees (p < 0.0001), but 0.07 m/s slower than conventional high-end prosthetic knees (p = 0.008). The PCI was similar across all three knee joint technologies (p = 0.276). CONCLUSIONS: Mobility function with the new knee joint, in terms of walking speed, was more closely matched to high-end than low-end prosthetic knee joints. Therefore, given its relatively simple design, the new stance phase control mechanism may offer a functional and cost effective solution for active transfemoral amputees. CLINICAL RELEVANCE: This paper describes a new type of prosthetic knee joint mechanism that is intended to be cost-effective while providing high-level stance phase function to active individuals with a transfemoral amputation. Initial clinical testing suggests that the new knee joint may have some functional advantages over existing technologies in this category.

A self-contained, mechanomyography-driven externally powered prosthesis.

The measurement of the low-frequency (5-50 Hz) "sounds" or vibrations produced by contracting muscles is termed mechanomyography (MMG). As a control signal for powered prostheses, MMG offers several advantages over conventional myoelectric control, including, nonspecific sensor placement, distal signal measurement, robustness to changing skin impedance, and reduced sensor costs. The objectives of this study were to demonstrate 2-function prosthesis control based on a triplet of distally recorded, normalized root mean square MMG signals and to identify necessary future research toward full clinical implementation of MMG signals in upper-limb externally powered prostheses. A novel self-contained MMG-driven prosthesis for below-elbow amputees was designed, implemented, and preliminarily tested on 2 subjects. This prosthesis was composed of specialized software and hardware modules that emulate a 2-site electromyography sensing system. Although the use of MMG signals for prosthesis control has been shown previously, we report, for the first time, successful control within a self-contained unit in unconstrained environments. Specifically, essential requirements for practical use, such as standardized sensor attachment, basic noise elimination, and miniaturization of the system, have been achieved. Both subjects were able to voluntarily open and close the prosthesis hand with no significant delays from intention to action (approximately 120 ms). Quantitative analyses revealed 88% and 71% control accuracy for subjects 1 and 2, respectively.