Upper extremity prosthetic selection influences loading of transhumeral osseointegrated systems.

Percutaneous osseointegrated (OI) implants are increasingly viable as an alternative to socket suspension of prosthetic limbs. Upper extremity prostheses have also become more complex to better replicate hand and arm function and attempt to recreate pre-amputation functional levels. With more functionality comes heavier devices that put more stress on the bone-implant interface, which could be an issue for implant stability. This study quantified transhumeral loading at defined amputation levels using four simulated prosthetic limb-types: (1) body powered hook, (2) myoelectric hook, (3) myoelectric hand, and (4) advanced prosthetic limb. Computational models were constructed to replicate the weight distribution of each prosthesis type, then applied to motion capture data collected during Advanced Activities of Daily Living (AADLs). For activities that did not include a handheld weight, the body powered prosthesis bending moments were 13-33% (range of means for each activity across amputation levels) of the intact arm moments (reference 100%), torsional moments were 12-15%, and axial pullout forces were 30-40% of the intact case (p≤0.001). The myoelectric hook and hand bending moments were 60-99%, torsional moments were 44-97%, and axial pullout forces were 62-101% of the intact case. The advanced prosthesis bending moments were 177-201%, torsional moments were 164-326%, and axial pullout forces were 133-185% of the intact case (p≤0.001). The addition of a handheld weight for briefcase carry and jug lift activities reduced the overall impact of the prosthetic model itself, where the body powered forces and moments were much closer to those of the intact model, and more complex prostheses further increased forces and moments beyond the intact arm levels. These results reveal a ranked order in loading magnitude according to complexity of the prosthetic device, and highlight the importance of considering the patient's desired terminal device when planning post-operative percutaneous OI rehabilitation and training.

Mobility Analysis of AmpuTees (MAAT 4): classification tree analysis for probability of lower limb prosthesis user functional potential.

Purpose: To develop a predictive model to inform the probability of lower limb prosthesis users' functional potential for ambulation.Materials and Methods: A retrospective analysis of a database of outcomes for 2770 lower limb prosthesis users was used to inform a classification and regression tree analysis. Gender, age, height, weight, body mass index adjusted for amputation, amputation level, cause of amputation, comorbid health status and functional mobility score [Prosthetic Limb Users Survey of Mobility (PLUS-M™)] were entered as potential predictive variables. Patient K-Level was used to assign dependent variable status as unlimited community ambulator (i.e., K3 or K4) or limited community/household ambulator (i.e., K1 or K2). The classification tree was initially trained from 20% of the sample and subsequently tested with the remaining sample.Results: A classification tree was successfully developed, able to accurately classify 87.4% of individuals within the model's training group (standard error 1.4%), and 81.6% within the model's testing group (standard error 0.82%). Age, PLUS-M™ T-score, cause of amputation and body weight were retained within the tree logic.Conclusions: The resultant classification tree has the ability to provide members of the clinical care team with predictive probabilities of a patient's functional potential to help assist care decisions.Implications for RehabilitationClassification and regression tree analysis is a simple analytical tool that can be used to provide simple predictive models for patients with a lower limb prosthesis.The resultant classification tree had an 81.6% (standard error 0.82%) accuracy predicting functional potential as an unlimited community ambulator (i.e., K3 or K4) or limited community/ household ambulator (i.e., K1 or K2) in an unknown group of 2770 lower limb prosthesis users.The resultant classification tree can assist with the rehabilitation team's care planning providing probabilities of functional potential for the lower limb prosthesis user.

Analyzing at-home prosthesis use in unilateral upper-limb amputees to inform treatment & device design.

New upper limb prosthetic devices are continuously being developed by a variety of industrial, academic, and hobbyist groups. Yet, little research has evaluated the long term use of currently available prostheses in daily life activities, beyond laboratory or survey studies. We seek to objectively measure how experienced unilateral upper limb prosthesis-users employ their prosthetic devices and unaffected limb for manipulation during everyday activities. In particular, our goal is to create a method for evaluating all types of amputee manipulation, including non-prehensile actions beyond conventional grasp functions, as well as to examine the relative use of both limbs in unilateral and bilateral cases. This study employs a head-mounted video camera to record participant's hands and arms as they complete unstructured domestic tasks within their own homes. A new 'Unilateral Prosthesis-User Manipulation Taxonomy' is presented based observations from 10 hours of recorded videos. The taxonomy addresses manipulation actions of the intact hand, prostheses, bilateral activities, and environmental feature-use (aiïordances). Our preliminary results involved tagging 23 minute segments of the full videos from 3 amputee participants using the taxonomy. This resulted in over 2,300 tag instances. Observations included that non-prehensile interactions outnumbered prehensile interactions in the affected limb for users with more distal amputation that allowed arm mobility.

Wearable technology for patients with brain and spinal cord injuries.

Studies have shown that patients who practice functional movements at home in conjunction with outpatient therapy show higher improvement in motor recovery. However, patients are not qualified to monitor or assess their own condition that must be reported back to the clinician. Therefore, there is a need to transmit physiological data to clinicians from patients in their home environment. This paper presents a review of wearable technology for in-home health monitoring, assessment, and rehabilitation of patients with brain and spinal cord injuries.

Reconstruction with modular megaprostheses for sarcomas of the lower extremity.

Limb-preserving surgery using modular megaprostheses for the reconstruction of large skeletal defects is currently the preferred treatment for sarcomas. The authors report the postoperative outcomes after skeletal resection for lower extremity sarcomas and the use of the METS cemented modular implant system (Stanmore Implants, Hertfordshire, United Kingdom) for reconstruction. They retrospectively studied 52 consecutive patients operated on from 2003 to 2012. There were 27 distal femur prostheses, 13 proximal femur, 11 proximal tibia, and 1 total femur implants. Patients were followed for a mean of 4.3 years. Overall patient survival, prosthesis survival, limb salvage rate, and secondary complications were documented. Five years postoperatively, prosthesis survival was 79%. Complications warranting implant revision surgery were documented in 15% of patients, whereas complications warranting surgery of any kind were observed in 27% of the patients. Nonmechanical complications, namely local relapse of the tumor and prosthetic infection, were the most common cause of prosthetic failure, accounting for 88% of major revision surgeries and 100% of amputations. Mechanical complications were rare, observed in only 6% of patients. No patients required secondary revision surgery. The limb salvage rate was 89%. Overall patient survival was 79% at 5 years and 71% at 10 years. The low risk for mechanical complications and the high limb salvage rate support the use of the METS modular megaprostheses for the reconstruction of skeletal defects following lower limb sarcoma surgery.

[Bioelectric prostheses: review of classifications and control strategies]. / Bioelectric prostheses: review of classifications and control strategies.

Bioelectric prosthesis are those mechatronical devices able to substitute the total or partial loss of a limb or a system, and controlled by the patient thanks to wilful bioelectric signals, such as muscular contractions (electromyographic signals, EMG) or activation of specific encephalic areas (which can be revealed by encephalogram, EEG). At the end of an analysis of the devices currently in literature and on the market, the present paper collects and synthesize the possible classification strategies of these prosthetic devices, paying particular attention also to the classification obtained by possible control strategies of the prosthesis. This summary aims to support and sustain physicians and patients along the identification of the most appropriate prosthesis, for the specific subject, the choice of the "optimal" device, must consider also patient needs and expectations, possible pathological constraints and technological complexity of the system. This paper presents, after a brief theoretical introduction about the background, a short description of materials and methods implemented in order to identify classification typologies; the main results, collected in 2 tables, will be then described, and commented highlighting advantages and limbs of the proposed classifications.

Comparison of mechanical energy profiles of passive and active below-knee prostheses: a case study.

BACKGROUND: With the recent technological advancements of prosthetic lower limbs, there is currently a great desire to objectively evaluate existing prostheses. Using a novel biomechanical analysis, the purpose of this case study was to compare the mechanical energy profiles of anatomical and two disparate prostheses: a passive prosthesis and an active prosthesis. CASE DESCRIPTION AND METHODS: An individual with a transtibial amputation who customarily wears a passive prosthesis (Elation, Össur) and an active prosthesis (BiOM, iWalk, Inc.) and 11 healthy subjects participated in an instrumented gait analysis. The total mechanical power and work of below-knee structures during stance were quantified using a unified deformable segment power analysis. FINDINGS AND OUTCOMES: Active prosthesis generated greater peak power and total positive work than passive prosthesis and healthy anatomical limbs. CONCLUSION: The case study will enhance future efforts to objectively evaluate prosthetic functions during gait in individuals with transtibial amputations. CLINICAL RELEVANCE: A prosthetic limb should closely replicate the mechanical energy profiles of anatomical limbs. The unified deformable (UD) analysis may be valuable to facilitate future clinical prescription and guide fine adjustments of prosthetic componentry to optimize gait outcomes.

Integration of surface electromyographic sensors with the transfemoral amputee socket: a comparison of four differing configurations.

BACKGROUND AND AIM: In recent years, there has been an increased interest in recording high-quality electromyographic signals from within the sockets of lower-limb amputees. However, successful recording presents major challenges to both researchers and clinicians. This article details and compares four prototypical integrated socket-sensor designs used to record electromyographic signals from within the sockets of transfemoral amputees. TECHNIQUE: Four prototypical socket-sensor configurations were constructed and tested on a single transfemoral amputee asked to perform sitting/standing, stair ascent/descent, and level ground walking. The number of large-amplitude motion artifacts generated using each prototype was quantified, the amount of skin irritation documented, and the comfort level of each assembly subjectively assessed by the amputee subject. DISCUSSION: Of the four configurations tested, the combination of a suction socket with integrated wireless surface electrodes generated the lowest number of large-amplitude motion artifacts, the least visible skin irritation, and was judged to be most comfortable by the amputee subject. CLINICAL RELEVANCE: The collection of high-quality electromyographic signals from an amputee's residual limb while maximizing patient comfort holds substantial potential to enhance neuromuscular clinical assessment and as a method of intuitive control of powered lower-limb prostheses.

Do users want to receive a DEKA Arm and why? Overall findings from the Veterans Affairs Study to optimize the DEKA Arm.

BACKGROUND: The purposes of this article are (1) to report on the overall desirability of the DEKA Arm by prototype and by level of prosthesis, (2) to report on user-perceived benefits of the DEKA Arm as compared to their current prostheses, and (3) to summarize user concerns about taking the device home. STUDY DESIGN: Qualitative content analysis of data from a multiple case study design. METHODS: This study utilized data from 24 upper-limb amputees fit with a Gen 2 DEKA Arm and 13 fit with a Gen 3 DEKA Arm. Surveys were administered after fitting the DEKA Arm and at the end of training. Subjects recorded audiotaped comments about their experiences. All study sessions were videotaped. RESULTS: In all, 79% of Gen 2 and 85% of Gen 3 users indicated that either they wanted to receive or might want to receive a DEKA Arm. In total, 95% of Gen 2 and 91% of Gen 3 prior prosthesis users reported that they were able to perform new activities that they were unable to perform with their own device. CONCLUSIONS: A large majority of subjects wanted a DEKA Arm, although desirability varied by amputation level. CLINICAL RELEVANCE: The majority of amputees in this study expressed a desire to receive the DEKA Arm, a device which provides multiple powered degrees of freedom and is operated predominantly by foot controls. The majority reported functional advantages of the DEKA Arm over their existing prostheses.

Influence of gait training and prosthetic foot category on external work symmetry during unilateral transtibial amputee gait.

BACKGROUND: Prosthetic foot prescription guidelines lack scientific evidence and are concurrent with an amputee's concurrent with an amputee's Medicare Functional Classification Level (K-Level) and categorization of prosthetic feet. OBJECTIVE: To evaluate the influence of gait training and four categories of prosthetic feet (K1, K2, K3, and microprocessor ankle/foot) on Symmetry in External Work for K-Level-2 and K-Level-3 unilateral transtibial amputees. DESIGN: Randomized repeated-measures trial. METHODS: Five K-Level-2 and five K-Level-3 subjects were tested in their existing prosthesis during Session 1 and again in Session 2, following 2 weeks of standardized gait training. In Sessions 3-6, subjects were tested using a study socket and one of four randomized test feet. There was an accommodation period of 10-14 days with each foot. Symmetry in External Work for positive and negative work was calculated at each session to determine symmetry of gait dynamics between limbs at self-selected walking speeds. RESULTS: K-Level-2 subjects had significantly higher negative work symmetry with the K3 foot, compared to K1/K2 feet. For both subject groups, gait training had a greater impact on positive work symmetry than test feet. CONCLUSION: Higher work symmetry is possible for K-Level-2 amputees who are trained to take advantage of K3 prosthetic feet designs. There exists a need for an objective determinant for categorizing and prescribing prosthetic feet.

A comparison between the suction suspension system and the hypobaric Iceross Seal-In® X5 in transtibial amputees.

BACKGROUND: The two passive vacuum suspension systems currently available in total surface-bearing sockets are the hypobaric Iceross Seal-In(®) and the suction suspension system. OBJECTIVES: The purpose of this study was to compare the effect of the hypobaric Iceross Seal-In(®) liner with that of the suction suspension system for quality of life, pistoning, and prosthesis efficiency in unilateral transtibial amputees. STUDY DESIGN: Single-group repeated measures. METHODS: Ten amputees were enrolled. The pistoning test, used to compare vertical movement of the stump within the socket, and the energy cost of walking test were carried out when the amputees were wearing the suction suspension system and after 2, 5, and 7 weeks of Seal-In® X5 use. The Prosthesis Evaluation Questionnaire and the Houghton Scale Questionnaire of perceived mobility and quality of life with the prosthesis, and the Timed Up&Go Test and the Locomotor Capability Index for functional mobility were also administered at the beginning and end of the study. RESULTS: The hypobaric Iceross Seal-In® X5 led to significant pistoning reduction and improvement on the Houghton Scale Questionnaire and 3 of 9 domains of the Prosthesis Evaluation Questionnaire. No statistical changes were observed in functional mobility or the energy cost of walking tests. CONCLUSION: Replacing the suction suspension system with the hypobaric Iceross Seal-In® X5 improves quality of life in transtibial amputees.

Ramp descent performance with the C-Leg and interrater reliability of the Hill Assessment Index.

BACKGROUND: Transfemoral amputees have decreased ability to descend ramps and hills. The Hill Assessment Index quantifies transfemoral amputee ramp performance, but interrater reliability has not been assessed. OBJECTIVES: To determine whether C-Leg use improves hill descent gait and evaluate the Hill Assessment Index's interrater reliability. METHODS: Twenty-one transfemoral amputees descended a ramp while timed and video recorded, using their nonmicroprocessor prosthetic knee. Subjects were fitted and accommodated with a C-Leg and retested. Test times were compared, and ramp performances were independently reviewed using the Hill Assessment Index by two raters. Hill Assessment Index scores were compared between knee conditions within raters for performance and between raters to assess the Hill Assessment Index's interrater reliability. RESULTS: Mean Hill Assessment Index scores were greater for C-Leg compared to nonmicroprocessor prosthetic knee for both raters. C-Leg resulted in faster ramp descent. Strong correlations resulted between raters on Hill Assessment Index scores for nonmicroprocessor prosthetic knee (intraclass correlation coefficient = 0.97) and C-Leg (intraclass correlation coefficient = 0.99). CONCLUSIONS: C-Leg improves Hill Assessment Index ramp descent performance and time. In descent quality, C-Leg offers the possibility of eliminating assistive device use and/or improving step length in the absence of an assistive device. C-Leg resulted in 23% gait speed increase during ramp descent. The Hill Assessment Index had very good interrater reliability but should be assessed for intrarater reliability, minimal detectable change, and validity.

Mechanisms to absorb load in amputee running.

BACKGROUND: We aimed to determine if a shock absorbing pylon (SAP) influenced the ground reaction force characteristics and the shock absorbing mechanisms compared to a rigid pylon (Rigid) during the loading phase in running. OBJECTIVES: To determine if the SAP influences the mechanisms of loading compared to the Rigid condition. STUDY DESIGN: A convenience sample of transtibial amputees participated in a laboratory-based study. The prosthetic set-up was randomly altered fd\sdsd. METHODS: Five recreationally active male transtibial amputees age: 18-50 years; mean mass: 86.7 ± 17.5 kg; height: 1.77 ± 0.07 m) volunteered from a population-based sample. They completed a within-participant-designed study assessing a SAP and a Rigid condition during running. Kinematic and kinetic data were collected during two sessions following a one-week customization period. RESULTS: Loading rate, peak vertical and horizontal ground reaction forces and the time to each measure along with knee and hip angular displacement, absorbing powers and work done between the SAP and Rigid conditions were not systematically affected by the prosthetic condition. CONCLUSIONS: The effect of the SAP was minimal and inconsistent in the loading phase, with only some amputees presenting higher and others with lower values for the tested variables.

Osseointegration amputation prostheses on the upper limbs: methods, prosthetics and rehabilitation.

BACKGROUND: The osseointegration programme for upper extremity amputation started in Sweden in 1990, when a titanium fixture was first implanted into a thumb. This method has since been used for transhumeral and below-elbow amputation. The treatment involves two surgical procedures. During the first a titanium fixture is surgically attached to the skeleton, and a second procedure six months later involves a skin penetrating abutment to which the prosthesis is attached. OBJECTIVES: To describe the osseointegration procedure for surgery, prosthetics and rehabilitation. METHODS: Patients with short stumps and previous problems with prosthetic fitting were selected. From 1990 to April 2010, 37 upper limb cases were treated and fitted with prosthesis: 10 thumbs, 1 partial hand, 10 transradial and 16 transhumeral amputations. Of these, 7 patients are currently not prosthetic users. RESULTS: Patients indicated that function and quality of life had improved since osseointegration. CONCLUSION: Osseointegration is an important platform for present and future prosthetic technology. The prosthetic situation is improved due to the stable fixation, freedom of motion and functionality. CLINICAL RELEVANCE: The two-stage osseointegration procedure has the potential to change the rehabilitation strategy for selected upper limb amputees. The method eliminates the need for a socket and the prosthesis will always fit. The stable prosthetic fixation and increased freedom of motion generates improved function. Specially designed components and rehabilitation procedures have been developed.

My prosthesis as a part of me: a qualitative analysis of living with an osseointegrated prosthetic limb.

BACKGROUND: Bone-anchored prosthesis is still a rather unusual treatment for patients with limb loss. OBJECTIVES: The aim of this study was to improve our understanding about the experience of living with an osseointegrated prosthesis (OI-prosthesis) compared to one suspended with a socket, through the use of qualitative research methodology. STUDY DESIGN: A qualitative phenomenological research method. METHODS: Thirteen Swedish patients (37-67 years) with unilateral upper or lower limb amputation (10 transfemoral, 2 transhumeral, 1 transradial), who had been using OI-prostheses for 3 to 15 years, were recruited by means of purposive sampling. An audio-taped in-depth interview was performed. The guiding question was 'How do you experience living with your osseointegrated prosthesis compared to your earlier prostheses suspended with sockets?'. The empirical phenomenological psychological method was used for data analysis. RESULTS: The results showed that all participants described living with an OI-prosthesis as a revolutionary change. These experiences were described in terms of three typologies, called 'Practical prosthesis', 'Pretend limb' and 'A part of me'. CONCLUSIONS: The most important finding was that the change went beyond the functional improvements, integrating the existential implications in the concept of quality of life. CLINICAL RELEVANCE: This qualitative in-depth interview study on patients using bone-anchored prosthetic limbs showed that all described a revolutionary change in their lives as amputees and the meaning of that change went beyond the functional improvements, integrating existential implications in the concept of quality of life.

[The skin frictional properties of 4 kinds of commonly used prosthetic materials].

Skin frictional properties of four kinds of prosthetic materials in common use have been researched. Experiments are carried out on residual limb and on normal tibia. Surface roughness and the hydrophobic/hydrophilic of the skin and materials are also tested. Under normal load 0.3 N and 0.7 N, the friction coefficient of silicon rubber and skin has the maximum value among all the materials due to the surface property of silicon rubber (containing oil). There is remarkable difference in friction coefficient between normal skin and amputee skin when they are in contact with silicon rubber (P<0.05). Other materials show "the higher the hydrophobia tendency of surface, the lower the friction coefficient". There are no significant differences (P>0.05) in friction coefficient between amputee skin and normal skin when they are in contact with all materials under normal load 8 N.

Testing of elastomeric liners used in limb prosthetics: classification of 15 products by mechanical performance.

The mechanical properties of 15 elastomeric liner products used in limb prosthetics were evaluated under compressive, frictional, shear, and tensile loading conditions. All testing was conducted at load levels comparable to interface stress measurements reported on transtibial amputee subjects. For each test configuration, materials were classified into four groups based on the shapes of their response curves. For the 15 liners tested, there were 10 unique classification sets, indicating a wide range of unique materials. In general, silicone gel liners classified within the same groups thus were quite similar to each other. They were of lower compressive, shear, and tensile stiffness than the silicone elastomer products, consistent with their lightly cross-linked, high-fluid content structures. Silicone elastomer products better spanned the response groups than the gel liners, demonstrating a wide range of compressive, shear, and tensile stiffness values. Against a skin-like material, a urethane liner had the highest coefficient of friction of any liner tested, although coefficients of friction values for most of the materials were higher than interface shear:pressure ratios measured on amputee subjects using Pelite liners. The elastomeric liner material property data and response groupings provided here can potentially be useful to prosthetic fitting by providing quantitative information on similarities and differences among products.

[The artificial hand. An overview of hand prostheses]. / Die Kunsthand. Ein Uberblick über die prothetische Versorgung der Hand.

In spite of constant demands made by patients for optimal reconstruction of the hand in cases of injury or amputation, prosthetic devices allow only basic functions of the hand. The most important function, i.e., to connect sensitive-tactile abilities of the hand with the eye and central nervous system, has not yet been achieved and will not be feasible in the near future. There have been numerous attempts to reconstruct single hand functions such as subtle finger control in all known directions etc. Until now none of these attempts have led to any serial production of a functional "tool" because the interface between prosthesis and CNS has not been sufficiently resolved. Minute finger control requires considerable mechanical engineering that includes an efficient motor drive and an adequate power supply,which renders possible prototypes for hand prostheses heavy and complicated in everyday performance. This survey offers a short and comprehensive introduction to high-performance but simple "down-to-earth" orthotic and prosthetic devices for the replacement of lost forearm,hand, and finger function.

Transtibial energy-storage-and-return prosthetic devices: a review of energy concepts and a proposed nomenclature.

Prosthetic devices that can store and return energy during gait enhance the mobility and functionality of lower-limb amputees. The process of selecting and fitting such devices is complicated, partly because of confusing literature on the topic. Gait analysis methods for measuring energy characteristics are often incomplete, leading to inconsistencies in the energy classifications of different products. These inconsistencies are part of the reason for the lack of universally accurate terminology in the field. Inaccurate terminology perpetuates misunderstanding. In this paper, important prosthetic energy concepts and methods for measuring energy characteristics are reviewed. Then a technically accurate nomenclature and a method of functional classification are proposed. This review and proposed classification scheme should help to alleviate confusion and should facilitate enhancement of the design, selection, and fitting of prosthetic limbs for amputee patients.

A pilot study comparing the cognitive demand of walking for transfemoral amputees using the Intelligent Prosthesis with that using conventionally damped knees.

OBJECTIVE: To compare the cognitive demand of walking when using a conventional prosthesis with that using a microprocessor-controlled prosthesis. DESIGN: Ten unilateral transfemoral amputees wearing conventional pneumatic swing phase control (conventional prosthesis) prostheses walked on a treadmill which enforced a pattern of constantly varying speeds. The subjects simultaneously performed a simple or a complex distracting task. Following a period of accustomization, the subjects performed the same test wearing a prosthesis with microprocessor control of swing phase damping (the Intelligent Prosthesis). OUTCOME MEASURES: The three-dimensional trajectory (sway) of a retroreflective marker attached to the forehead was measured by a video-based motion analysis system, and used as a measure of gait quality. The ratio of the sway for the complex task over the simple task (the 'automation index') was used as a measure of the degree of automation of gait. RESULTS: No significant differences were found in the automation index between the two devices. However, the total sway for the conventional prosthesis was significantly higher. Sway during the complex distracting task was significantly higher than during the simple task. CONCLUSIONS: The microprocessor-controlled prosthesis was not found to be less cognitively demanding than a conventional prosthesis.