Evaluating the Ability of Congenital Upper Extremity Amputees to Control a Multi-Degree of Freedom Myoelectric Prosthesis.

PURPOSE: To determine whether children and adults with unilateral congenital upper limb amputation can control myoelectric prostheses with multiple degrees of freedom (DOF) using pattern recognition (PR) technology. METHODS: Seven participants (age 9-62 years) with unilateral congenital transradial amputation were tested on both their residual and sound side limbs to determine proficiency in controlling a virtual prosthesis using electromyographic signals captured by an array of surface electrodes that were processed using PR technology. Proficiency was measured through a virtual environment game called the target achievement control test, in which the testing protocol asked participants to match increasingly complex prosthesis postures with 1, 2, and 3 DOF. RESULTS: All the participants successfully created a PR calibration at 1, 2, and 3 DOF with their residual limb during testing, and no differences in calibration accuracy were observed when comparing the residual versus sound upper limbs. No differences were noted in the mean completion rate on the target achievement control test between the residual and sound limbs. CONCLUSIONS: Participants with a congenital upper limb amputation achieved PR control calibration of multi-DOF prostheses with proficiency and quality results of PR calibration that were comparable to those of their sound limb. This capability was observed in children as well as in adults. This demonstrates the potential for children and adults with a unilateral congenital transradial amputation to benefit from myoelectric prostheses with PR control. CLINICAL RELEVANCE: The results from this study highlight the potential for patients in this population to benefit from myoelectric prostheses with PR control. Persons with unilateral congenital upper limb amputations can be considered for provision of this technology and enrollment in future research activities.

Survey of U.S. Practitioners on the Validity of the Medicare Functional Classification Level System and Utility of Clinical Outcome Measures for Aiding K-Level Assignment.

OBJECTIVE: To characterize the opinion of the prosthetic clinical care community on the Medicare Functional Classification Level (K-level) assignment process to classify the mobility and rehabilitation potential of persons with lower-limb loss, including limitations and practicalities involved with the integration of outcome measures (OMs) into the clinical practice framework for K-level assignment. DESIGN: Survey. SETTING: English online questionnaire with built-in logic. PARTICIPANTS: Volunteer sample of prosthetics practitioners (N=236). Data were analyzed only for U.S. practitioners (n=213). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Subjective responses to 19 multiple choice, Likert scale, and open-ended questions. RESULTS: Forty-seven percent of respondents indicated that they were the sole determinant in the K-level assignment process, while 43% indicated that it was a collaborative process with other health care professionals. Sixty-nine percent of respondents reported using standardized OMs to assist in K-level assignment, and most did not agree that commonly reported barriers to implementation (eg, lack of time and training) were relevant. Sixty-seven percent of respondents did not believe the K-level system can accurately assign a level of rehabilitation potential, with 75% agreeing that incorporating OMs into clinical practice would enhance objectivity of the K-level assignment process. CONCLUSIONS: The results suggest that most prosthetics practitioners are involved in the K-level assignment at some level, and most agreed that there are considerable limitations with this system. To address these issues, many practitioners are using OMs to assess various aspects of patient mobility and rehabilitation potential, and minimize the subjectivity of the assignment process.

Novel 3D-printed foot orthoses with variable hardness: A comfort comparison to traditional orthoses.

Custom foot orthoses are used to treat a variety of foot pathologies. However, orthotic production requires significant hands-on fabrication time and expertise to produce orthoses that are both comfortable and effective. This paper introduces a novel 3D printed orthosis and fabrication method that utilizes custom architectures to produce variable-hardness regions. These novel orthoses are compared to traditionally fabricated orthoses during a 2-week user comfort study. Twenty (n = 20) male volunteers underwent orthotic fitting for both traditional and 3D-printed foot orthoses prior to engaging in treadmill walking trials and 2 weeks of wear. Each participant undertook a regional comfort, acceptance, and comparison analysis of the orthoses at three time points throughout the study (0, 1, and 2 weeks). Both the 3D-printed and the traditionally fabricated foot orthoses demonstrated statistically significant increases in comfort when compared to the factory fabricated shoe insert. Additionally, the two orthosis groups were not significantly different from each other in comfort rankings both regionally and overall at any time point. The similar comfort achieved by the 3D-printed orthosis to the traditionally fabricated orthosis after 7 days and 14 days emphasizes the potential of the future use of the more reproducible and adaptable 3D-printed orthosis manufacturing methodology.

A Biomimetic Adapter for Passive Self-alignment of Prosthetic Feet.

INTRODUCTION: Dynamic alignment of lower limb prostheses is subjective and time-consuming. Compensatory gait strategies caused by prosthesis misalignment can negatively affect lower limb amputees who cannot access a certified prosthetist for alignment adjustments. The objective of this study is to evaluate a novel six-degrees-of-freedom passive transtibial prosthetic adapter that self-aligns during various phases of gait. This self-aligning adapter may benefit service members and veterans stationed or living far from a clinical facility. METHODS: Four transtibial amputee subjects, aged 47 to 62 (mean: 55.75) years with mean weight of 163.6 lbs and mean K-level of 3.25, walked at self-selected speeds on a 10-m level walkway. Subjects walked with the self-aligning and a size- or weight-matched control adapter, assembled to a commercially available energy-storing-and-returning foot and their own socket, with 22-mm alignment perturbations in the anterior, posterior, medial, or lateral directions. Subjects were blinded to both adapter type and misalignment. Socket moments, spatiotemporal gait parameters, and subjective socket comfort were recorded. RESULTS: Preliminary results showed improvements in mean peak socket moments and step length differential with the self-aligning adapter across all alignments. Walking speed and prosthesis-side base of support showed little change in all configurations. Prosthesis-side stance duration and Functional Ambulation Profile Score increased with the self-aligning adapter in some alignments. Patient-reported socket comfort increased slightly with the self-aligning adapter across all misalignments. CONCLUSION: Subjects maintained similar walking speeds and experienced greater gait symmetry and reduced sagittal plane peak moments with the self-aligning adapter when exposed to misalignments. These trends suggest a benefit to transtibial amputees from a reduction in secondary gait effects from prosthesis misalignments. Additionally, a wider range of acceptable prosthesis alignments may be possible with the self-aligning adapter. Subsequent trials are underway to evaluate the self-aligning adapter in real-world environments like walking on uneven terrains, stairs, ramps, and abrupt turns.

Predict the Medicare Functional Classification Level (K-level) using the Amputee Mobility Predictor in people with unilateral transfemoral and transtibial amputation: A pilot study.

BACKGROUND: While Amputee Mobility Predictor scores differ between Medicare Functional Classification Levels (K-level), this does not demonstrate that the Amputee Mobility Predictor can accurately predict K-level. OBJECTIVES: To determine how accurately K-level could be predicted using the Amputee Mobility Predictor in combination with patient characteristics for persons with transtibial and transfemoral amputation. STUDY DESIGN: Prediction. METHOD: A cumulative odds ordinal logistic regression was built to determine the effect that the Amputee Mobility Predictor, in combination with patient characteristics, had on the odds of being assigned to a particular K-level in 198 people with transtibial or transfemoral amputation. RESULTS: For people assigned to the K2 or K3 level by their clinician, the Amputee Mobility Predictor predicted the clinician-assigned K-level more than 80% of the time. For people assigned to the K1 or K4 level by their clinician, the prediction of clinician-assigned K-level was less accurate. The odds of being in a higher K-level improved with younger age and transfemoral amputation. CONCLUSION: Ordinal logistic regression can be used to predict the odds of being assigned to a particular K-level using the Amputee Mobility Predictor and patient characteristics. This pilot study highlighted critical method design issues, such as potential predictor variables and sample size requirements for future prospective research. Clinical relevance This pilot study demonstrated that the odds of being assigned a particular K-level could be predicted using the Amputee Mobility Predictor score and patient characteristics. While the model seemed sufficiently accurate to predict clinician assignment to the K2 or K3 level, further work is needed in larger and more representative samples, particularly for people with low (K1) and high (K4) levels of mobility, to be confident in the model's predictive value prior to use in clinical practice.

PSYCHOMETRIC EVALUATION OF THE HILL ASSESSMENT INDEX (HAI) AND STAIR ASSESSMENT INDEX (SAI) IN HIGH-FUNCTIONING TRANSFEMORAL AMPUTEES.

The hill assessment index (HAI) and stair assessment index (SAI) were developed to objectively evaluate ramp and stair gait. This study's purpose was to determine the validity and reliability of these tests in a sample of persons with unilateral transfemoral amputation (TFA) using microprocessor prosthetic knee systems. All subjects were fit with a microprocessor knee system. After accommodation, subjects performed three trials ascending and descending a 5° ramp and a flight of stairs while being recorded on video. Sensitivity and specificity for the HAI was calculated against degree of asymmetry in step length using Dartfish video analysis software. Reliability was assessed using intraclass correlational coefficients calculated using Spearman's Rho (rs). A priori significance level was set at p ≤ 0.05. Twenty (n = 20) individuals with TFA completed the study protocol. Sensitivity and specificity of the HAI were calculated at 88.0% and 75.0% during ascending conditions and 94.0% and 67.0% during descending conditions, respectively. Significant correlations for the HAI included rs = 0.87 and rs = 0.73 within raters uphill and downhill, respectively. Corresponding coefficients of rs = 0.80 and rs = 0.67 were calculated between raters. For the SAI, significant correlations included rs = 1.00 for both comparisons within raters and in the comparison between raters in the ascending condition. A correlation of rs = 0.89 was calculated for the between-rater comparison in the descending condition. The HAI showed moderate to excellent sensitivity and specificity but good to adequate reliability. The SAI showed excellent to good reliability.