A review of evidence on mechanical properties of running specific prostheses and their relationship with running performance.

Background: Although mechanical properties of running specific prostheses (RSPs) can affect running performance, manufacturers do not consistently report them. This study aimed to review existing literature on RSP mechanical and structural properties and their relationship with running performance. Methods: A comprehensive search was conducted using keywords related to mechanical properties of RSPs and running performance. Search terms included stiffness and hysteresis, as well as performance outcomes including metabolic cost and running speed. Non-peer-reviewed and non-English publications were excluded. Results: Twenty articles were included in the review. Sixteen studies used a material testing machine to measure RSP material properties, and four articles used other techniques including 2D/3D video capture and force platforms. Both measurement techniques and reporting of outcomes were inconsistent, which limits the ability to draw broad conclusions. Additionally, several studies did not report the numerical data for material properties despite measuring them. Relatively few articles measured both material properties and running performance and assessed correlations. Conclusion: Several articles connected prosthesis properties to running performance. However, inconsistent measurement and reporting of mechanical properties, along with the multifactorial nature of the athlete-prosthesis system, limit the ability to draw broad conclusions regarding the relationship between material and structural properties and athlete performance. Current evidence may be useful for clinicians seeking ways to optimize RSP stiffness in a case-by-case basis; however, clinicians would benefit from more consistent and systematic comparisons of the attributes of different RSPs and their role in performance.

Assessment of knee flexion in young children with prosthetic knee components using dynamic time warping.

Introduction: Analysis of human locomotion is challenged by limitations in traditional numerical and statistical methods as applied to continuous time-series data. This challenge particularly affects understanding of how close limb prostheses are to mimicking anatomical motion. This study was the first to apply a technique called Dynamic Time Warping to measure the biomimesis of prosthetic knee motion in young children and addressed the following research questions: Is a combined dynamic time warping/root mean square analysis feasible for analyzing pediatric lower limb kinematics? When provided at an earlier age than traditional protocols dictate, can children with limb loss utilize an articulating prosthetic knee in a biomimetic manner? Methods: Warp costs and amplitude differences were generated for knee flexion curves in a sample of ten children five years of age and younger: five with unilateral limb loss and five age-matched typically developing children. Separate comparisons were made for stance phase flexion and swing phase flexion via two-way ANOVAs between bilateral limbs in both groups, and between prosthetic knee vs. dominant anatomical knee in age-matched pairs between groups. Greater warp costs indicated greater temporal dissimilarities, and a follow-up root mean square assessed remaining amplitude dissimilarities. Bilateral results were assessed by age using linear regression. Results: The technique was successfully applied in this population. Young children with limb loss used a prosthetic knee biomimetically in both stance and swing, with mean warp costs of 12.7 and 3.3, respectively. In the typically developing group, knee motion became more symmetrical with age, but there was no correlation in the limb loss group. In all comparisons, warp costs were significantly greater for stance phase than swing phase. Analyses were limited by the small sample size. Discussion: This study has established that dynamic time warping with root mean square analysis can be used to compare the entirety of time-series curves generated in gait analysis. The study also provided clinically relevant insights on the development of mature knee flexion patterns during typical development, and the role of a pediatric prosthetic knee.

Effects of Two Exercise Programs on Neck Proprioception in Patients with Chronic Neck Pain: A Preliminary Randomized Clinical Trial.

BACKGROUND: The purpose of this study was to compare the effects of specific neck muscle training and general neck-shoulder exercises on neck proprioception, pain, and disability in patients with chronic non-specific neck pain. METHODS: Twenty-five patients with chronic non-specific neck pain were recruited into this preliminary single-blinded randomized clinical trial. They were randomly assigned to either a specific neck exercise (n = 13, mean aged 24 years) or a general neck exercise group (n = 12, mean aged 25 years). Specific neck exercises included eye-head coordination and isometric deep neck muscle exercises. General neck exercises included neck and shoulder free range of motion and shoulder shrug. Pain, disability, and neck proprioception, which was determined using the joint repositioning error, were measured at baseline and after eight weeks of training in both groups. RESULTS: Both training groups showed significant improvements in joint repositioning error (p < 0.001, F = 24.144, ES = 0.8), pain (p < 0.001, F = 61.118, ES = 0.31), and disability (p = 0.015, F = 6.937, ES = 0.60). However, the specific neck exercise group showed larger variability in joint repositioning error (p = 0.006, F = 0.20, F critical = 0.36). CONCLUSIONS: Either specific neck exercise or a general neck-shoulder range of motion exercise could be effective in improving neck proprioception. Therefore, exercises could be recommended based on patient comfort and patients' specific limitations.

Rehabilitative ultrasound imaging of the levator scapula muscle at rest and during contraction: Technical description and reliability.

BACKGROUND: Altered scapular muscle activity is associated with abnormal scapular motions and shoulder pain. Hence, quantification of these activities is a challenging issue. OBJECTIVES: The purposes of this study were to establish the reliability of measuring levator scapula muscle thickness and to examine how thickness of this muscle changes with contraction. METHODS: Twenty-one asymptomatic individuals (mean age 22.29 ± 2.17 years) participated in this study. Three separate ultrasound images of the levator scapula muscle were captured at the neck-shoulder junction at rest and during a loaded isometric contraction. The procedures were repeated twice, four to seven days apart to establish intra-rater test-retest reliability. Interclass correlation coefficients (ICC) and standard error of measurement (SEM) were used to determine the reliability, and a paired t-test was performed to examine the difference in muscle thickness between two conditions. RESULTS: The results demonstrated that intra-examiner reliability was good at rest (ICC = 0.88, SEM = 1.16 mm) and excellent during loaded isometric contraction (ICC = 0.95, SEM = 0.91 mm). Furthermore, the thickness of levator scapula muscle significantly increased from rest to the loaded isometric contraction (Effect size = 1.99, P < 0.001). CONCLUSION: This study demonstrates that the thickness of the levator scapula muscle can be measured reliably at the neck-shoulder junction. Furthermore, ultrasound measures can reliably detect changes in muscle thickness from rest to a contracted state. Therefore, if the need exists to evaluate muscle morphology before and after any treatment strategy, thickness measurement of levator scapula can be determined reliably using ultrasound.

Influence of non-immersive avatar-based gamification on the Hawthorne Effect in pediatric gait.

BACKGROUND: The Hawthorne Effect occurs when participants alter their behavior when they are aware that they are being examined. The effect has been reported in many experiments, including gait analysis, and is considered an important source of bias that might impact both clinical and research results. Cognitive distraction is one potential solution to reducing the Hawthorne effect during gait analysis, but it is challenging in children, and can, in itself, alter gait. This study investigated the carryover effect of an alternative low-immersion avatar-based intervention on gait and subjective feelings in typically developing children. RESEARCH QUESTION: Will a low-immersion avatar-based intervention change feelings and indicators of temporospatial and kinematic outcomes in children in a laboratory setting, potentially reducing the Hawthorne Effect? METHODS: Typically developing children aged 5-13 participated in a standard laboratory gait analysis before experiencing a game in which they viewed their motion on monitors around the lab as that of a cartoon avatar in a 3D virtual environment. Following this intervention, standard walking trials were repeated. In addition, participants completed a survey of their feelings about the study both before onset and after completion. RESULTS: Thirty-one children participated in the study, 16 females and 15 males, mean aged 9.1 years. Arm swing, proposed as a measure of how relaxed and natural gait was, increased significantly following the intervention, while temporospatial parameters did not. The effect was more pronounced in females and younger children. Participants felt significantly happier, more excited, less scared, and less sad after the intervention. Changes in feelings were not closely associated with changes in gait. SIGNIFICANCE: This study suggests that gamification may reduce the Hawthorne effect and potentially produce more natural gait in children. The game intervention had a carryover effect, producing changes in gait even after the intervention was removed.

Four-Week Ankle-Rehabilitation Programs in Adolescent Athletes With Chronic Ankle Instability.

CONTEXT: Researchers have shown that rehabilitation programs incorporating resistance-band and balance-board exercises are effective for improving clinical measures of function and patient-reported outcomes in individuals with chronic ankle instability (CAI). However, whether combining the 2 exercises increases improvement is unknown. OBJECTIVE: To determine the effectiveness of 3 rehabilitation programs on clinical measures of balance and self-reported function in adolescent patients with CAI. DESIGN: Randomized controlled clinical trial (Trail Registration Number: ClinicalTrails.gov: NCT03447652). SETTING: High school athletic training facilities. PATIENTS OR OTHER PARTICIPANTS: Forty-three patients with CAI (age = 16.37 ± 1.00 years, height = 171.75 ± 12.05 cm, mass = 69.38 ± 18.36 kg) were block randomized into 4 rehabilitation groups. INTERVENTION(S): Protocols were completed 3 times per week for 4 weeks. The resistance-band group performed 3 sets of 10 repetitions of ankle plantar flexion, dorsiflexion, inversion, and eversion with a resistance band. The Biomechanical Ankle Platform System group performed 5 trials of clockwise and counterclockwise rotations, changing direction every 10 seconds during each 40-second trial. The combination group completed resistance-band and Biomechanical Ankle Platform System programs during each session. The control group did not perform any exercises. MAIN OUTCOME MEASURE(S): Variables were assessed before and after the intervention: time-in-balance test, foot-lift test, Star Excursion Balance Test, side-hop test, figure-8 hop test, Foot and Ankle Ability Measure, and Cumberland Ankle Instability Tool. We conducted 4 separate multivariate repeated-measures analyses of variance, followed by univariate analyses for any findings that were different. RESULTS: Using the time-in-balance test, foot-lift test, Star Excursion Balance Test (medial, posteromedial, and posterolateral directions), and figure-8 hop test, we detected improvement for each rehabilitation group compared with the control group (P < .05). However, no intervention group was superior. CONCLUSIONS: All 3 rehabilitation groups demonstrated improvement compared with the control group, yet the evidence was too limited to support a superior intervention. Over a 4-week period, either of the single-task interventions or the combination intervention can be used to combat the residual deficits associated with CAI in an adolescent patient population.

Walking kinematics in young children with limb loss using early versus traditional prosthetic knee prescription protocols.

The traditional treatment protocol for young children with congenital or acquired amputations at or proximal to the knee prescribes a prosthesis without a working knee joint, based in part on the assumption that a child learning to walk cannot properly utilize a passively flexing prosthetic knee component. An alternative to this Traditional Knee (TK) protocol is an "Early Knee" (EK) protocol, which prescribes an articulating prosthetic knee in the child's first prosthesis, during development of crawling and transitioning into and out of upright positions. To date, no study has compared samples of children with limb loss at or proximal to the knee using TK and EK protocols. The purpose of this multi-site study was to examine kinematic outcomes during walking in separate groups of young children in an EK and a TK prosthesis protocol, along with a population of children without lower limb amputations. Eighteen children aged 12 months to five years were recruited for this study at two clinical sites, six in each of the three groups. Children in the two prosthesis groups had unilateral limb loss and had been treated either at one site with the TK protocol or at another with the EK protocol. Children in the EK group achieved swing phase prosthetic knee flexion averaging 59.8±8.4 degrees. Children wearing prosthetic limbs walked slower than age-matched peers. In most instances, walking speed and step length increased with age in the EK group, similar to the control group. However, this trend was not observed in the TK group. Clearance adaptations were present in both limb loss groups. Observed adaptations were twice as prevalent in the TK group versus the EK group; however, the groups differed in age and etiology. Children with limb loss provided with an articulating knee component in their first prosthesis incorporated knee flexion during swing phase and showed fewer gait adaptations than children in the TK protocol.

Confirmation bias affects user perception of knee braces.

Technological advances in orthopedic devices such as prostheses and orthoses are intended to improve function but may also result in increased complexity and expense. Consequently, accurate determination of effectiveness is important. When devices with advanced technology are used, it is possible that confirmation bias - the tendency for a user to actually experience what he or she expects to experience - will influence outcomes. This study assessed confirmation bias in 18 healthy young adults walking in knee braces. Participants wore two identical braces, but one was cosmetically modified and participants were told that it was a prototype computerized brace that could dynamically alter its stiffness. Before using the braces, the majority of users indicated a preference for the "computerized" brace. Actual walking showed no differences between the two braces. Following walking, users maintained preference for the "computerized" brace, indicating the presence of confirmation bias. These results underscore the importance of blinding when self-reported outcomes are used and the need to consider a placebo effect when comparing orthopedic devices.

A novel method for the measurement of linear body segment parameters during clinical gait analysis.

Clinical gait analysis is a valuable tool for the understanding of motion disorders and treatment outcomes. Most standard models used in gait analysis rely on predefined sets of body segment parameters that must be measured on each individual. Traditionally, these parameters are measured using calipers and tape measures. The process can be time consuming and is prone to several sources of error. This investigation explored a novel method for rapid recording of linear body segment parameters using magnetic-field based digital calipers commonly used for a different purpose in prosthetics and orthotics. The digital method was found to be comparable to traditional in all linear measures and data capture was significantly faster with the digital method, with mean time savings for 10 measurements of 2.5 min. Digital calipers only record linear distances, and were less accurate when diameters were used to approximate limb circumferences. Experience in measuring BSPs is important, as an experienced measurer was significantly faster than a graduate student and showed less difference between methods. Comparing measurement of adults vs. children showed greater differences with adults, and some method-dependence. If the hardware is available, digital caliper measurement of linear BSPs is accurate and rapid.

Custom-molded foot-orthosis intervention and multisegment medial foot kinematics during walking.

CONTEXT: Foot-orthosis (FO) intervention to prevent and treat numerous lower extremity injuries is widely accepted clinically. However, the results of quantitative gait analyses have been equivocal. The foot models used, participants receiving intervention, and orthoses used might contribute to the variability. OBJECTIVE: To investigate the effect of a custom-molded FO intervention on multisegment medial foot kinematics during walking in participants with low-mobile foot posture. DESIGN: Crossover study. SETTING: University biomechanics and ergonomics laboratory. PATIENTS OR OTHER PARTICIPANTS: Sixteen participants with low-mobile foot posture (7 men, 9 women) were assigned randomly to 1 of 2 FO groups. INTERVENTION(S): After a 2-week period to break in the FOs, individuals participated in a gait analysis that consisted of 5 successful walking trials (1.3 to 1.4 m/s) during no-FO and FO conditions. MAIN OUTCOME MEASURE(S): Three-dimensional displacements during 4 subphases of stance (loading response, midstance, terminal stance, preswing) were computed for each multisegment foot model articulation. RESULTS: Repeated-measures analyses of variance (ANOVAs) revealed that rearfoot complex dorsiflexion displacement during midstance was greater in the FO than the no-FO condition (F(1,14) = 5.24, P = .04, partial η(2) = 0.27). Terminal stance repeated-measures ANOVA results revealed insert-by-insert condition interactions for the first metatarsophalangeal joint complex (F(1,14) = 7.87, P = .01, partial η(2) = 0.36). However, additional follow-up analysis did not reveal differences between the no-FO and FO conditions for the balanced traditional orthosis (F(1,14) = 4.32, P = .08, partial η(2) = 0.38) or full-contact orthosis (F(1,14) = 4.10, P = .08, partial η(2) = 0.37). CONCLUSIONS: Greater rearfoot complex dorsiflexion during midstance associated with FO intervention may represent improved foot kinematics in people with low-mobile foot postures. Furthermore, FO intervention might partially correct dysfunctional kinematic patterns associated with low-mobile foot postures.

An instrumented wheel system for measuring 3-D pushrim kinetics during racing wheelchair propulsion.

The purpose of this study was to design and validate an instrumented wheel system (IWS) that can measure 3-dimensional (3-D) pushrim forces during racing wheelchair propulsion. Linearity, precision, and percent error were determined for both static and dynamic conditions. For the static condition, the IWS demonstrated a high linearity (0.91

Assessing the state of clinically applicable research for evidence-based practice in prosthetics and orthotics.

Evidence-based practice combines a practitioner's training and experience with evidence established through scientific research. Fundamental to the evidence-based process for prosthetics and orthotics is the ongoing availability of clinically applicable research on relevant conditions, components, and patient populations. In the past, research has been successfully applied to practice, sometimes producing substantial changes. Examples include clinically applicable research that has assessed treatment effectiveness, altered clinical patient interaction, led to the development of new components and technologies, and challenged or changed long-standing clinical opinion. Despite past successes, obstacles remain in the application of research to practice. Practitioners have stated a desire for research and have identified a list of research needs but lack the training or resources necessary to conduct the research. A gulf also exists between the perceived research needs and the clinically applicable research that is being produced, possibly because of the broad nature of those needs.

The effect of low-mobile foot posture on multi-segment medial foot model gait kinematics.

A number of in vitro, invasive in vivo, and non-invasive marker based multi-segment foot models (MSFMs) have reported significant motion in the articulations distal to the calcaneus during gait. Few studies, however, have applied a MSFM to the investigation of the effect of foot posture on gait kinematics. Differences in stance phase kinematics between participants with low-mobile (LMF) (n=11) versus "typical" (TYPF) (n=11) foot postures were investigated using a multi-segment medial foot model. Three-dimensional position and stance phase excursions of four functional articulations (rearfoot complex [RC], calcaneonavicular complex [CNC], medial forefoot, first metatarsophalangeal complex) were quantified using an eight optical camera motion analysis system (Vicon Motus, Vicon Motions Systems, Centennial, CO) and a custom written software program (Matlab 7.0.1, The MathWorks, Natick, MA), respectively. Excursions during four subphases of stance phase (loading response, midstance, terminal stance, pre-swing) at each of the functional articulations were compared using multivariate analyses of variance (alpha

Consistency, precision, and accuracy of optical and electromagnetic shape-capturing systems for digital measurement of residual-limb anthropometrics of persons with transtibial amputation.

Computer-aided design (CAD) and computer-aided manufacturing systems have been adapted for specific use in prosthetics, providing practitioners with a means to digitally capture the shape of a patient's limb, modify the socket model using software, and automatically manufacture either a positive model to be used in the fabrication of a socket or the socket itself. The digital shape captured is a three-dimensional (3-D) model from which standard anthropometric measures can be easily obtained. This study recorded six common anthropometric dimensions from CAD shape files of three foam positive models of the residual limbs of persons with transtibial amputations. Two systems were used to obtain 3-D models of the residual limb, a noncontact optical system and a contact-based electromagnetic field system, and both experienced practitioners and prosthetics students conducted measurements. Measurements were consistent; the mean range (difference of maximum and minimum) across all measurements was 0.96 cm. Both systems provided similar results, and both groups used the systems consistently. Students were slightly more consistent than practitioners but not to a clinically significant degree. Results also compared favorably with traditional measurement, with differences versus hand measurements about 5 mm. These results suggest the routine use of digital shape capture for collection of patient volume information.

Comparison of infant head shape changes in deformational plagiocephaly following treatment with a cranial remolding orthosis using a noninvasive laser shape digitizer.

Deformational Plagiocephaly (DP) is a multi-planar deformity of the cranium occurring either pre-or postnatally in infants. In the last decade, the incidence of DP has increased substantially due to a number of factors, including supine sleeping positioning to reduce Sudden Infant Death Syndrome and the use of child carriers that increase supine positioning. Clinical questions persist about which children should be treated for DP and how to intervene, questions that are difficult to answer without accurate documentation of three-dimensional (3-D) head shape. This study explored a method for quantifying head shape and used that method to evaluate the success of orthotic treatment. Two hundred twenty-four infants who were diagnosed with DP received either a cranial remolding orthosis or a repositioning program with no orthotic intervention. Data from 25 head shape variables were collected using a noninvasive laser shape digitizer. Only variables attributable to growth showed significant differences in the control population, while the treatment population showed significant differences in pre-and post-treatment values for all variables. The study identified four variables as particularly important in assessing the head shape of infants with plagiocephaly: the cranial vault asymmetry index, radial symmetry index, posterior symmetry ratio, and overall symmetry ratio. Ninety-six percent or more of subjects in the treatment group showed improvement in each variable. These data document the utility of a 3-D scanning device and the effectiveness of treatment with a cranial remolding orthosis.

Consistency and accuracy of measurement of lower-limb amputee anthropometrics.

Lower-limb amputees often exhibit large fluctuation in residual-limb shape, necessitating careful observation and anthropometric measurement for prosthetists to ensure socket fit. Anthropometric measurement may become more important as an outcome measure indicating success in rehabilitation. This study investigated the accuracy and reliability of seven prosthetic anthropometric measurement devices as used by a group of eight prosthetic-orthotic practitioners and a group of five prosthetic-orthotic students to measure six common anthropometric dimensions on three foam positive models of transtibial amputee residual limbs. Two of the models were identical, enabling assessment of individual repeatability. Some clinically significant errors were noted in the results; however, the general variability in measurements was not clinically significant. Students were slightly more consistent than practitioners; students were more consistent with linear measurements, while practitioners were more consistent with circumferential measures. The results further demonstrated that the VAPC measurement device used in the study was both inaccurate and unreliable.

An iterative method for viscoelastic modeling of prosthetic feet.

Prosthetic foot designs are growing in complexity, but a few material and structural properties, including stiffness and viscoelasticity, remain critical to foot function. Consistent identification of these critical properties would aid prosthesis prescription. This investigation evaluates a new technique to model prosthetic feet as a combination of springs and dampers, and therefore characterize a foot's stiffness and viscoelasticity by means of spring and damper coefficients. A quasi-Newton iterative algorithm was developed to determine model coefficients for 9 prosthetic feet based on compressive creep, stress-relaxation, and constant strain rate tests. A broad range of current energy-storing feet including designs from Otto Bock, Seattle, Kingsley, and Ohio Willow Wood were very accurately modeled with the iterative technique. Feet without a solid ankle from Flex and College Park were the least accurately modeled. The Flex foot, tested without a cover, had a considerably lower damping coefficient. Damper coefficients were similar for most all other feet, suggesting similar material properties of the foam cover. Stiffness varied and generally agreed with published data. The ability of the model to produce two separate parallel spring stiffness constants might provide insight into foot structure. The model represents a means to objectively quantify material properties for a range of solid ankle dynamic elastic response prosthetic feet, but may be limited in its characterization of other foot varieties.