Brian J. Hafner

Energy storage and return prostheses: does patient perception correlate with biomechanical analysis?

The development and prescription of energy storage and return prosthetic feet in favor of conventional feet is largely based upon prosthetist and amputee experience. Regretfully, the comparative biomechanical analysis of energy storage and return and conventional prosthetic feet is rarely a motivation to either the technical development or clinical prescription of such devices. The development and prescription of prosthetic feet without supportive scientific evidence is likely due to the conflicting or non-significant results often presented in the scientific literature. Despite the sizeable history of comparative prosthetic literature and continued analysis of prosthetic components, the link between clinical experience and scientific evidence remains largely unexplored.A review of the comparative analysis literature evaluating energy storage and return and conventional prosthetic feet is presented to illustrate consistencies between the perceptive assessments and the objective biomechanical data. Results suggest that while experimental methodologies may limit the statistical significance of objective gait analysis results, consistent trends in temporal, kinetic, and kinematic parameters correlate well with perceptive impressions of these feet. These correlations provide insight to subtle changes in gait parameters that are deemed neither clinically nor statistically significant, yet are perceived by amputees to affect their preference for and performance of prosthetic feet during locomotion. Acknowledging and targeting areas of perceptive significance will help researchers develop more structured protocols for energy storage and return prosthesis evaluation as well as provide clinicians with information needed to enhance the appropriateness of their clinical recommendations. Expanding test environments to measure activities of perceived improvement such as high-velocity motions, stair ascent/descent, and uneven ground locomotion will provide a more appropriate assessment of the conditions for which energy storage and return prosthetic feet were designed. Concentrating research to specific test populations by age or amputation etiologies can overcome statistical limitations imposed by small study samples. Finally, directing research toward the areas of gait adaptation, heel performance, and the temporal release of energy in energy storage and return feet may reinforce the selection and utilization of advanced prosthetic components. These enhancements to current biomechanical analyses may serve to reduce the boundaries of perceptive significance and provide clinicians, designers, and researchers with the supportive data needed to prescribe, design, and evaluate energy storage and return prosthetic feet.

Differences in function and safety between Medicare Functional Classification Level-2 and -3 transfemoral amputees and influence of prosthetic knee joint control

The functional differences between persons with amputation who are classified as Medicare Functional Classification Level (MFCL)-2 and -3 include the abilities to walk at various cadences and to negotiate environmental barriers outside the home. This study compared the effect of active microprocessor control and passive mechanical control of the prosthetic knee on function and safety in 17 subjects with transfemoral amputation (8 MFCL-2 and 9 MFCL-3). Assessed functional tasks included hill and stair descent, an attentional demand task, and an obstacle course. Self-reported measures included concentration, multitasking ability, and numbers of stumbles and falls. Active knee control was associated with significant improvements (p < 0.05) in hill and stair gait, speed (hills, obstacle course, and attentional demand task), and ability to multitask while walking for both cohorts. MFCL-2 subjects also reported a significant reduction (p < 0.01) in uncontrolled falls. Over the study, 50% of MFCL-2 subjects and 33% of MFCL-3 subjects transitioned to a higher MFCL. Results suggest that active knee control improves function and reduces the frequency of adverse events in a population that is at risk for falls. Use of active knee control may allow persons with amputation to expand their functional domain, transition to a higher MFCL, and access additional prosthetic options.

Effect of a Foot-Drop Stimulator and Ankle–Foot Orthosis on Walking Performance After Stroke A Multicenter Randomized Controlled Trial

Background. Studies have demonstrated the efficacy of functional electrical stimulation in the management of foot drop after stroke. Objective. To compare changes in walking performance with the WalkAide (WA) foot-drop stimulator and a conventional ankle–foot orthosis (AFO). Methods. Individuals with stroke within the previous 12 months and residual foot drop were enrolled in a multicenter, randomized controlled, crossover trial. Subjects were assigned to 1 of 3 parallel arms for 12 weeks (6 weeks/device): arm 1 (WA–AFO), n = 38; arm 2 (AFO–WA), n = 31; arm 3 (AFO–AFO), n = 24. Primary outcomes were walking speed and Physiological Cost Index for the Figure-of-8 walking test. Secondary measures included 10-m walking speed and perceived safety during this test, general mobility, and device preference for arms 1 and 2 for continued use. Walking tests were performed with (On) and without a device (Off) at 0, 3, 6, 9, and 12 weeks. Results. Both WA and AFO had significant orthotic (On–Off difference), therapeutic (change over time when Off), and combined (change over time On vs baseline Off) effects on walking speed. An AFO also had a significant orthotic effect on Physiological Cost Index. The WA had a higher, but not significantly different therapeutic effect on speed than an AFO, whereas an AFO had a greater orthotic effect than the WA (significant at 12 weeks). Combined effects on speed after 6 weeks did not differ between devices. Users felt as safe with the WA as with an AFO, but significantly more users preferred the WA. Conclusions. Both devices produce equivalent functional gains.

Outcomes associated with the use of microprocessor-controlled prosthetic knees among individuals with unilateral transfemoral limb loss: A systematic review

Microprocessor-controlled prosthetic knees (MPKs) have been developed as an alternative to non-microprocessor-controlled knees (NMPKs) to address challenges facing individuals with lower-limb loss. A body of scientific literature comparing MPKs and NMPKs exists but has yet to be critically appraised. Therefore, we conducted a systematic review to examine outcomes associated with the use of these interventions among individuals with transfemoral limb loss. A search of biomedical databases identified 241 publications, of which 27 met the inclusion and exclusion criteria and were reviewed for methodological quality and content. We developed 28 empirical evidence statements (EESs) in 9 outcome categories (metabolic energy expenditure, activity, cognitive demand, gait mechanics, environmental obstacle negotiation, safety, preference and satisfaction, economics, and health and quality of life) based on findings in the literature. The level of evidence supporting these EESs varied due to quantity, quality, and consistency of the results. EESs supported by a moderate level of evidence that noted significant differences between MPKs and NMPKs were derived in five of the nine outcome categories. The results from this review suggest that evidence exists to inform clinical practice and that additional research is needed to confirm existing evidence and better understand outcomes associated with the use of NMPKs and MPKs.

Clinical Prescription and Use of Prosthetic Foot and Ankle Mechanisms: A Review of the Literature

AState-of-the-Science Conference (SSC) is designed to provide a systematic review of literature and ranking of evidence on a conference topic. The purpose is to evaluate the available scientific information on an aspect of orthotic and prosthetic (O&P) care and develop statements that advance understanding of the issues in question that will be useful to health professionals and the public. It may also serve as a mechanism to document clinical belief systems in O&P care, based on what is understood through sound research or from expert opinion. The end goals of an SSC are to publish a document that identifies and ranks the available evidence and defines the current status of patient care, to develop consensus on controversial issues where possible, and to identify research priorities. The focus of this SSC and this literature review is the body of scientific evidence that supports the clinical prescription and use of prosthetic foot and ankle mechanisms.

Long-term activity in and among persons with transfemoral amputation

Although physical limitations associated with transfemoral amputation (TFA) have been studied in laboratory settings, little is known about habitual activity within free-living environments. A retrospective analysis of 12 mo of step activity data was performed to quantify activity levels, variations, and patterns in 17 adults with unilateral TFA. Yearly, seasonal, and monthly average daily step counts and coefficients of variation (CoVs) were examined to characterize mobility. Analysis by Medicare Functional Classification Level (MFCL) was performed to explore relationships between clinical classification and performance. Subjects averaged 1,540 prosthetic steps/day, and activity generally increased with MFCL. Activity between MFCL-2 and -3 subjects was not significantly different, suggesting that ability to engage in habitual physical activity may be similar for these groups. Relative variation (CoV) was 0.65 across subjects but was lower for those with higher activity levels. No significant differences in CoV by group were detected. Marked seasonal and monthly patterns in activity were identified. Warmer seasons and months generally promoted higher activity, but peak temperatures and humidity depressed activity. Results suggest that persons with TFA are greatly limited in regards to activity. Further, large variations within and between subjects may challenge the interpretation of step activity gathered over short periods of time.

Changes in interface pressure and stump shape over time: Preliminary results from a trans-tibial amputee subject

Interface stresses and stump shape were measured during sessions over a twomonth interval on a transtibial amputee subject. Results from thirteen transducer sites monitored during four sessions showed greater interface pressure changes over time at anterior sites than at lateral or posterior locations. There was a trend of decreased pressure with stump swelling and increased pressure for stump atrophy. During one session in which stump shape was monitored over a 23.1 min interval after ambulation, stump swelling was localised. Swelling tended to increase in the regions of initial enlargement, as opposed to redistributing through different areas over time. Regions of swelling were anterior lateral and posterior proximal, areas of thick underlying soft tissue. Identification of localised areas of swelling and atrophy and understanding of their effects on interface pressures could be used to improve individual socket design.

Health-Related Profiles of People With Lower Limb Loss

OBJECTIVES To construct profiles of self-reported health indicators to examine differences and similarities between people with lower limb loss and a normative sample (hereafter called the norm) and to compare health indicators between subgroups based on level and etiology of limb loss. DESIGN Survey. SETTING General community. PARTICIPANTS Adults with unilateral lower limb loss (N=1091) participated in this study. Eligibility criteria included lower limb loss due to trauma or dysvascular complications and regular use of a prosthesis. INTERVENTIONS Not applicable. MAIN OUTCOME MEASURES The Patient-Reported Outcomes Measurement Information System 29-item Health Profile version 1.0 measures physical function, pain interference, fatigue, sleep disturbance, anxiety, depression, and satisfaction with participation in social roles. The norm includes 5239 individuals representative of the U.S. general population in sex, age, race, ethnicity, and education. RESULTS People with lower limb loss reported statistically significantly worse physical function, pain interference, and satisfaction with participation in social roles and significantly less fatigue than did the norm. People with transfemoral (ie, above-knee) amputation significantly differed in physical function from people with transtibial (ie, below-knee) amputation. Similarly, people with amputation due to trauma and dysvascular etiology significantly differed in physical function and satisfaction with social roles after adjusting for relevant clinical characteristics. CONCLUSIONS People with lower limb loss generally report worse physical function, pain interference, and satisfaction with social roles than do the norm. People with dysvascular amputation reported worse physical function and satisfaction with social roles than did people with traumatic amputation. Health indicator profiles are an efficient way of providing clinically meaningful information about numerous aspects of self-reported health in people with lower limb loss.

Postural asymmetries in transfemoral amputees.

Background: Postural asymmetries are thought to lead to impairment of body structure and function such as muscle imbalance, gait asymmetry and possible chronic conditions, which result in limitation of mobility and restriction of daily activity for transfemoral amputees (TFAs). Despite the potential clinical impact, postural asymmetries have not been confirmed or quantified in TFAs. Objectives: To identify the presence of postural asymmetries in TFAs utilizing clinical evaluation measures. Study design: An observational cross-sectional study in which participants were evaluated at a single time point without intervention or follow-up. Methods: Forty-seven unilateral TFAs were measured for standing limb length, pelvic innominate inclination (PII), lateral trunk flexion and hip extension. Results: Limb length discrepancy was present in 66% of participants and 57% had a short prosthetic limb. PII was greater than has been reported in the literature, and the shorter the prosthetic lower limb, the greater the PII on the amputated side (r = −0.422, p = 0.004). Limb length discrepancy and decreased lateral trunk flexion accounted for 26% of the variance in amputated side PII. Conclusion: Three postural measurements, namely leg length, pelvic innominate inclination and hip extension, were found to differ between the intact and amputated limb in this study sample. Clinical relevance Clinicians should include postural assessment as part of their routine evaluation of TFAs in an effort to achieve postural symmetry and reduce the risk of chronic conditions associated with impairment of body structure and function.

Use of and confidence in administering outcome measures among clinical prosthetists: Results from a national survey and mixed-methods training program.

Background: Outcome measures can be used in prosthetic practices to evaluate interventions, inform decision making, monitor progress, document outcomes, and justify services. Strategies to enhance prosthetists’ ability to use outcome measures are needed to facilitate their adoption in routine practice. Objective: To assess prosthetists’ use of outcome measures and evaluate the effects of training on their confidence in administering performance-based measures. Study design: Cross-sectional and single-group pretest–posttest survey. Methods: Seventy-nine certified prosthetists (mean of 16.0 years of clinical experience) were surveyed about their experiences with 20 standardized outcome measures. Prosthetists were formally trained by the investigators to administer the Timed Up and Go and Amputee Mobility Predictor. Prosthetists’ confidence in administering the Timed Up and Go and Amputee Mobility Predictor was measured before and after training. Results: The majority of prosthetists (62%) were classified as non-routine outcome measure users. Confidence administering the Timed Up and Go and Amputee Mobility Predictor prior to training was low-to-moderate across the study sample. Training significantly (p < 0.0001) improved prosthetists’ confidence in administering both instruments. Conclusion: Prosthetists in this study reported limited use of and confidence with standardized outcome measures. Interactive training resulted in a statistically significant increase of prosthetists’ confidence in administering the Timed Up and Go and Amputee Mobility Predictor and may facilitate use of outcome measures in clinical practice. Clinical relevance Frequency of outcome measure use in the care of persons with limb loss has not been studied. Study results suggest that prosthetists may not regularly use standardized outcome measures and report limited confidence in administering them. Training enhances confidence and may encourage use of outcome measures in clinical practice.