Sex and gender differences in upper extremity prosthesis rejection: A review of literature.

Prosthesis rejection is a significant barrier to rehabilitation of persons with upper limb difference. Many individual factors can affect device rejection, including a person's sex or gender. The objective of this narrative review was to explore the reported differences between the sexes and genders in upper limb prosthesis rejection. This review considered peer-reviewed, published research studies in which the study population were adults (aged 18 and older) who had unilateral or bilateral limb difference (any level) of any etiology with current, past, or no history of prosthetic device usage. Using identified keywords, index terms, and a peer-reviewed search filter, the literature was searched in MEDLINE, Embase, and PsycInfo. The reasons for rejection, disuse, or abandonment of prosthetic devices were extracted, with the focus on reported differences between sex and genders. After searching, 29 articles were selected for full-text review and 15 were included. Only 5 of 15 articles examined differences between the sexes. Women tend to reject upper extremity prostheses more than men both before and after being fit with a device; device characteristics, such as weight and cosmesis, do not appear to be appropriately designed for women; and there may not be adequate consideration of the goals for women with limb difference(s). There is inadequate reporting of sex and gender in the literature on prosthesis rejection; future studies should report and explore these factors to determine whether the needs of the full population with limb loss are being met.

Bone-anchored prostheses for transfemoral amputation: a systematic review of outcomes, complications, patient experiences, and cost-effectiveness.

Introduction: Bone-anchored prostheses (BAP) are an advanced reconstructive surgical approach for individuals who had transfemoral amputation and are unable to use the conventional socket-suspension systems for their prostheses. Access to this technology has been limited in part due to the lag between the start of a new procedure and the availability of evidence that is required before making decisions about widespread provision. This systematic review presents as a single resource up-to-date information on aspects most relevant to decision makers, i.e., clinical efficacy, safety parameters, patient experiences, and health economic outcomes of this technology. Methods: A systematic search of the literature was conducted by an information specialist in PubMed, MEDLINE, Embase, CINAHL, Cochrane Library, the Core Collection of Web of Science, CADTH's Grey Matters, and Google Scholar up until May 31, 2023. Peer-reviewed original research articles on the outcomes of clinical effectiveness (health-related quality of life, mobility, and prosthesis usage), complications and adverse events, patient experiences, and health economic outcomes were included. The quality of the studies was assessed using the Oxford Centre for Evidence-Based Medicine Levels of Evidence and ROBINS-I, as appropriate. Results: Fifty studies met the inclusion criteria, of which 12 were excluded. Thirty-eight studies were finally included in this review, of which 21 reported on clinical outcomes and complications, 9 case series and 1 cohort study focused specifically on complications and adverse events, and 2 and 5 qualitative studies reported on patient experience and health economic assessments, respectively. The most common study design is a single-arm trial (pre-/post-intervention design) with varying lengths of follow-up. Discussion: The clinical efficacy of this technology is evident in selected populations. Overall, patients reported increased health-related quality of life, mobility, and prosthesis usage post-intervention. The most common complication is a superficial or soft-tissue infection, and more serious complications are rare. Patient-reported experiences have generally been positive. Evidence indicates that bone-anchored implants for prosthesis fixation are cost-effective for those individuals who face significant challenges in using socket-suspension systems, although they may offer no additional advantage to those who are functioning well with their socket-suspended prostheses.

Biomechanical characteristics of transfemoral bone-anchored prostheses during gait: A review of literature.

BACKGROUND: Osseointegration (OI) is an emerging technique that allows a direct connection between the bone and a titanium metal implant, allowing the direct attachment of bone-anchored prostheses (BAP) to address the problems associated with socket prostheses. This review article aims to compare the biomechanical features of gait when using a transfemoral BAP in comparison to healthy gait, and in comparison to the gait of traditional transfemoral socket prosthesis users. METHODS: A computer-based literature search of electronic databases since inception (ranging from 1967 to 2004 depending on the database) to June 14, 2022, identified peer-reviewed articles focusing on the temporal-spatial, kinematic, kinetic, and electromyography data related to transfemoral BAP gait. Eight articles were included that focused on these biomechanical features of gait in adults with BAP and were compared with socket prosthesis users or healthy gait. RESULTS: Compared with healthy participants, prosthesis users after OI surgery have slower speed and cadence, lower symmetry, longer duration of swing phase, increased pelvic and trunk motion, more hip extension, larger moments on the intact limb, and lower forces on the prosthetic side. Compared with transfemoral socket prosthesis gait, BAP gait shows faster cadence and longer duration of support phase. There are limited and inconsistent data on changes in trunk, pelvic, and hip motion with OI. CONCLUSION: Based on this review, transfemoral BAP improve spatial-temporal parameters closer to normal gait when compared to socket gait, but there are persisting deficits compared with healthy gait. Additional studies are needed to confirm the changes in kinematics and kinetics when walking with a BAP.

A scoping review of eye tracking metrics used to assess visuomotor behaviours of upper limb prosthesis users.

Advanced upper limb prostheses aim to restore coordinated hand and arm function. However, this objective can be difficult to quantify as coordinated movements require an intact visuomotor system. Eye tracking has recently been applied to study the visuomotor behaviours of upper limb prosthesis users by enabling the calculation of eye movement metrics. This scoping review aims to characterize the visuomotor behaviours of upper limb prosthesis users as described by eye tracking metrics, to summarize the eye tracking metrics used to describe prosthetic behaviour, and to identify gaps in the literature and potential areas for future research. A review of the literature was performed to identify articles that reported eye tracking metrics to evaluate the visual behaviours of individuals using an upper limb prosthesis. Data on the level of amputation, type of prosthetic device, type of eye tracker, primary eye metrics, secondary outcome metrics, experimental task, aims, and key findings were extracted. Seventeen studies were included in this scoping review. A consistently reported finding is that prosthesis users have a characteristic visuomotor behaviour that differs from that of individuals with intact arm function. Visual attention has been reported to be directed more towards the hand and less towards the target during object manipulation tasks. A gaze switching strategy and delay to disengage gaze from the current target has also been reported. Differences in the type of prosthetic device and experimental task have revealed some distinct gaze behaviours. Control factors have been shown to be related to gaze behaviour, while sensory feedback and training interventions have been demonstrated to reduce the visual attention associated with prosthesis use. Eye tracking metrics have also been used to assess the cognitive load and sense of agency of prosthesis users. Overall, there is evidence that eye tracking is an effective tool to quantitatively assess the visuomotor behaviour of prosthesis users and the recorded eye metrics are sensitive to change in response to various factors. Additional studies are needed to validate the eye metrics used to assess cognitive load and sense of agency in upper limb prosthesis users.

A Modular Adjustable Transhumeral Prosthetic Socket for Evaluating Myoelectric Control.

Novel myoelectric control strategies may yield more robust, capable prostheses which improve quality of life for those affected by upper-limb loss; however, the development and translation of such strategies from an experimental setting towards daily use by persons with limb loss is a slow and costly process. Since prosthesis functionality is highly dependent on the physical interface between the user's prosthetic socket and residual limb, assessment of such controllers under realistic (noisy) environmental conditions, integrated into prosthetic sockets, and with participants with amputation is essential for obtaining representative results. Unfortunately, this step is particularly difficult as participant- and control strategy-specific prosthetic sockets must be custom-designed and manufactured. There is thus a need for a system to reduce these burdens and facilitate this crucial phase of the development pipeline. This study aims to address this gap through the design and assessment of an inexpensive and easy-to-use 3D-printed Modular-Adjustable transhumeral Prosthetic Socket (MAPS). This 3D-printed, open-source socket was developed in consultation with prosthetists and compared with a participant-specific suction socket in a single-participant case-study. We conducted mechanical and functional assessments to ensure that the developed socket enabled similar performance compared to participant-specific sockets. Both socket systems yielded similar results in mechanical and functional assessments, as well as in self-reported user feedback. The MAPS system shows promise as a research tool which catalyzes the development and deployment of novel myoelectric control strategies by better-enabling comprehensive assessment involving participants with amputations.

Mechanotactile Sensory Feedback Improves Embodiment of a Prosthetic Hand During Active Use.

There have been several advancements in the field of myoelectric prostheses to improve dexterity and restore hand grasp patterns for persons with upper limb loss, including robust control strategies, novel sensory feedback, and multifunction prosthetic terminal devices. Although these advancements have shown to improve prosthesis performance, a key element that may further improve acceptance is often overlooked. Embodiment, which encompasses the feeling of owning, controlling and locating the device without the need to constantly look at it, has been shown to be affected by sensory feedback. However, the specific aspects of embodiment that are influenced are not clearly understood, particularly when a prosthesis is actively controlled. In this work, we used a sensorized simulated prosthesis in able-bodied participants to investigate the contribution of sensory feedback, active motor control, and the combination of both to the components of embodiment; using a common methodology in the literature, namely the rubber hand illusion (RHI). Our results indicate that (1) the sensorized simulated prosthesis may be embodied by able-bodied users in a similar fashion as prosthetic devices embodied by persons with upper limb amputation, and (2) mechanotactile sensory feedback might not only be useful for improving certain aspects of embodiment, i.e., ownership and location, but also may have a modulating effect on other aspects, namely sense of agency, when provided asynchronously during active motor control tasks. This work may allow us to further investigate and manipulate factors contributing to the complex phenomenon of embodiment in relation to active motor control of a device, enabling future study of more precise quantitative measures of embodiment that do not rely as much on subjective perception.

Osseointegration for Lower-Limb Amputation: A Systematic Review of Clinical Outcomes.

BACKGROUND: Traditional socket prostheses are not a viable option for all lower-limb prosthetic users. Discomfort, pain in the residual limb, and problems related to the fit of the socket are common and have been shown to negatively impact quality of life and mobility. Osseointegrated or bone-anchored prosthetic implants have evolved over the past 2 decades as a promising alternative for patients who are experiencing substantial issues with socket prostheses. METHODS: A review of the literature was performed to identify studies focusing on the evolution, clinical outcomes, success rates, and complications of osseointegrated lower-limb prostheses. Articles were summarized according to the implant type, amputation level, and study characteristics, with rating of the Level of Evidence. Information on patient selection criteria, outcomes, and complications was extracted. RESULTS: Fourteen articles (with Level-II, III, or IV evidence) met the inclusion criteria. Infection and soft-tissue irritation at the stoma were the most common complications. It is evident that, over the years, changes in implant design, surgical technique, perioperative and postoperative care, and rehabilitation protocols have resulted in improvements in functional outcomes and health-related quality of life, and reduction in rates of complications. CONCLUSIONS: Osseointegration for limb amputation has become an established clinical treatment option for persons with lower-limb amputation not tolerating traditional socket prostheses. Osseointegration could provide substantial benefits regarding function and quality of life for appropriately selected patients who accept the documented risks. LEVEL OF EVIDENCE: Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Associations compete directly in memory.

Associations are confusable when they share an item. For example, double-function pairs (with the form AB, BC) are harder to remember than control pairs. Although ambiguous pairs are more difficult on average, it is not clear whether memories for associations compete directly with one another (associative competition hypothesis), as assumed by models that incorporate associative symmetry (bidirectional associations). Alternatively, associative interference results might be explained away by: (a) item suppression hypothesis: competition only between memory for the two target items (A and C are both targets of B); (b) candidate competition hypothesis: The cue (B) retrieves two potential targets, A and C, which compete to be output. These alternative hypotheses could explain previous results in the related, AB/AC learning procedure. Our procedure included a large amount of interference that had to be resolved within a single study set. Participants studied sets of control (single-function) and double-function pairs and were asked to produce one or two associates, respectively, to cue items. Recall of AB and BC were negatively correlated and could not be explained away by item suppression or competition between simultaneously retrieved candidate items. Thus, competition can occur at the level of representation of associations, regardless of which item is the cue, consistent with associative symmetry.

Interference and the representation of order within associations.

In the presence of interference, recall of pairs can critically depend on the diagnostic power of memory of the order of items within the pair. Models of pair memory make different assumptions about whether and how such order information is stored, from convolution-based models, which assume no explicit storage of order, to matrix models and several models that assume a pair is learned by concatenating the representations of the constituent items, which lead to perfect within-pair order memory (given retrieval of the pair). Here we investigate memory for associations and within-pair order by examining the relationship between forward and backward probes of pairs subject to order-dependent associative interference in a double-function list paradigm. Associative interference disrupted the high correlation between forward and backward recall accuracy that is typically observed in standard paired-associate learning, challenging matrix and concatenation-based models. However, participants could overcome some interference due to within-pair order ambiguity, challenging directionally ambiguous convolution-based models. Unexpectedly, the test-retest correlation was reduced for pairs under the influence of interference compared to control pairs. This finding is incompatible with all existing implementations of the model classes we consider. Any model must include an assumption that order encoding (but not retrieval) is unreliable, and the form of this additional mechanism may depend intimately on how a given model is designed. In sum, our findings suggest that within-pair order memory is neither poor nor perfect, pointing to a fallible mechanism for within-pair order learning in verbal association-memory tasks.