Evaluation of an instrument-assisted dynamic prosthetic alignment technique for individuals with transtibial amputation.

BACKGROUND: A prosthesis that is not optimally aligned can adversely influence the rehabilitation and health of the amputee. Very few studies to date evaluate the effectiveness and utility of instrument-assisted alignment techniques in clinical practice. OBJECTIVES: To compare an instrument-assisted dynamic alignment technique (Compas(™)) to conventional methods. STUDY DESIGN: In a crossover study design, dynamic prosthetic alignments were provided to nine individuals with unilateral transtibial amputations to compare conventional and instrument-assisted alignment techniques. METHODS: The instrument-assisted technique involved a commercially available force and torque sensing dynamic alignment system (Compas). Cadence, pelvic accelerations, and socket moments were assessed. A custom questionnaire was used to gather user perceptions. RESULTS: No differences between alignment techniques were found in global gait measures including cadence and pelvic accelerations. No significant alignment differences were achieved by examination of angular changes between the socket and foot; however, significantly higher below-the-socket moments were found with the instrument-assisted technique. From the questionnaire, six amputees had no preference, while three preferred the conventional alignment. CONCLUSION: The use of Compas appears to produce similar alignment results as conventional techniques, although with slightly higher moments at the socket. CLINICAL RELEVANCE: This study provides new information about the clinical utilization of instrument-assisted prosthetic alignment techniques for individuals with transtibial amputation.

A pilot study examining measures of balance and mobility in children with unilateral lower-limb amputation.

BACKGROUND: Individuals with unilateral lower-limb amputation (LLA) have altered structure and physiology of their lower limbs which impairs their balance, mobility, physical function and participation in physical activities. As part of (re)habilitation, focus is given to improving gait and balance in order to enhance overall mobility, function, self-efficacy, and independence. However, the relationships amongst body impairments and physical activity limitations remain unclear, particularly in the pediatric population. OBJECTIVE: To provide an examination of the relationships among balance and mobility measures in children with unilateral lower-limb amputation and able-bodied children. STUDY DESIGN: Cross-sectional prospective comparative pilot study. METHODS: Spatiotemporal gait parameters and standing postural control were evaluated in children with lower-limb amputation (n = 10) and age-matched able-bodied children (n = 10) in a laboratory-based setting. Clinical tests for mobility and balance consisted of the 10-m walk test, the 6-min walk test, and the Community Balance and Mobility scale. Energy expenditure was estimated during the 6-min walk test using the Physiological Cost Index. Analysis included comparing variables between able-bodied and lower-limb amputation groups, as well as examining the correlations among them. RESULTS: Walking speed, distance, and functional balance (p < 0.05) were significantly diminished in children with lower-limb amputation compared to able-bodied children. For children with lower-limb amputation, reduced energy expenditure was associated with narrower step width and more symmetrical gait; better postural control and balance were associated with faster walking speeds (p < 0.05). CONCLUSION: A greater clinical understanding of gait and balance deficits in this population may help to improve rehabilitation outcomes and overall functional mobility. CLINICAL RELEVANCE: Improved understanding of deficits in children with lower-limb amputation (LLA) may lead to more targeted interventions and facilitate clinical decision-making in rehabilitation settings for this population. The findings contribute to the limited literature and provide a basis to further examine suitable clinical outcome measures to be used in children with LLA.

Toward an artificial sensory feedback system for prosthetic mobility rehabilitation: examination of sensorimotor responses.

People with lower-limb amputation have reduced mobility due to loss of sensory information, which may be restored by artificial sensory feedback systems built into prostheses. For an effective system, it is important to understand how humans sense, interpret, and respond to the feedback that would be provided. The goal of this study was to examine sensorimotor responses to mobility-relevant stimuli. Three experiments were performed to examine the effects of location of stimuli, frequency of stimuli, and means for providing the response. Stimuli, given as vibrations, were applied to the thigh region, and responses involved leg movements. Sensorimotor reaction time (RT) was measured as the duration between application of the stimulus and initiation of the response. Accuracy of response was also measured. Overall average RTs for one response option were 0.808 +/- 0.142 s, and response accuracies were >90%. Higher frequencies (220 vs 140 Hz) of vibration stimulus provided in anterior regions of the thigh produced the fastest RTs. When participants were presented with more than one stimulus and response option, RTs increased. Findings suggest that long sensorimotor responses may be a limiting factor in the development of an artificial feedback system for mobility rehabilitation applications; however, feed-forward techniques could potentially help to address these limitations.

Preliminary evaluation of a commercially available videogame system as an adjunct therapeutic intervention for improving balance among children and adolescents with lower limb amputations.

OBJECTIVES: To examine the safety, feasibility, and balance performance effects of a 4-week home-based balance therapy program using a commercially available videogame system. DESIGN: A pilot study involving a preintervention and postintervention design was conducted with measurements taken at baseline, immediately postintervention (week 5), and at follow-up (week 13) for retention. SETTING: University hospital outpatient clinic and participants' places of residence. PARTICIPANTS: Children and adolescents with unilateral lower limb amputation (n=6; 3 transfemoral [TF] and 3 Van Ness) and age-matched, typically developing individuals (n=10) for baseline comparison. INTERVENTION: Two videogames involving weight shifting in standing were each played at home for 20 min/d, 4d/wk for a period of 4 weeks. A physical therapist provided initial instruction and monitoring. MAIN OUTCOME MEASURES: Postural control characteristics using center of pressure (COP) displacements during quiet standing; functional balance using the Community Balance and Mobility Scale (CB&M); and compliance, safety, and feasibility using custom questionnaires. RESULTS: Average playing times for the first 3 weeks ranged from 16.0 to 21.1 minutes for the 2 games. At baseline, the children and adolescents with TF amputation had substantially greater COP displacements than the Van Ness group and typically developing children and adolescents. Immediately postintervention, the COP displacements decreased in the TF amputees, resulting in values that were closer to those of the typically developing children. The average increase in CB&M score from baseline to follow-up was 6 points across participants. CONCLUSIONS: In-home, videogame-based balance training therapies can achieve excellent compliance in children and adolescents with lower limb amputation. With proper instructions and monitoring, the therapeutic intervention can be safely administered. Some improvements in postural control characteristics were seen in children and adolescents with balance deficits immediately postintervention, but long-term retention remains unclear.

Mobility function of a prosthetic knee joint with an automatic stance phase lock.

BACKGROUND: There is a need for a prosthetic knee joint design that is technologically and functionally appropriate for use in developing countries. OBJECTIVES: To develop and clinically evaluate a new type of stance phase controlled prosthetic knee joint that provides stance phase stability without inhibiting swing phase flexion. STUDY DESIGN: A crossover repeated measures study design comparing the new knee joint to the participant's conventional low- or high-end prosthetic knee joint. METHODS: The new knee joint was fitted to fourteen individuals aged 15 to 67 years with unilateral lower limb amputations. Walk tests were performed to measure walking speed. Energy expenditure was estimated using the physiological cost index (PCI). RESULTS: Walking speeds with the new knee joint were on average 0.14 m/s faster than conventional low-end knees (p < 0.0001), but 0.07 m/s slower than conventional high-end prosthetic knees (p = 0.008). The PCI was similar across all three knee joint technologies (p = 0.276). CONCLUSIONS: Mobility function with the new knee joint, in terms of walking speed, was more closely matched to high-end than low-end prosthetic knee joints. Therefore, given its relatively simple design, the new stance phase control mechanism may offer a functional and cost effective solution for active transfemoral amputees. CLINICAL RELEVANCE: This paper describes a new type of prosthetic knee joint mechanism that is intended to be cost-effective while providing high-level stance phase function to active individuals with a transfemoral amputation. Initial clinical testing suggests that the new knee joint may have some functional advantages over existing technologies in this category.

Estudio piloto para evaluar la utilización de tecnología CAD/CAM en la fabricación central de cuencas prótesicas en México / Pilot trial for assessment of CAM-CAD computerized technology for unified manufacturing of external prosthetic sockets for amputees

Por vez primera se realizó un estudio piloto entre México (centro de rehabilitación) y Canadá (centro de manufactura) para evaluar la fabricación central de cuencas protésicas utilizando tecnología CAD/CAM. En CRIMAL (Querétaro), se tomó el molde negativo de tres muñones trans-tibiales y las medidas anatómicas de cuatro muñones trans-femorales. Las medidas trans-femorales fueron capturadas y modificadas por computadora en CRIMAL. La geometría digital generada por CAD fue transmitida vía modem a The Rehabilitation Center (Ottawa) para fabricar las cuencas por CAM. Estas cuencas fueron enviadas por mensajería a México y por autobús a Querétaro. Los moldes trans-tibiales fueron trasladados a Ottawa donde se digitalizaron y modificaron numéricamente para despúes fabricar las cuencas y transportarlas a Querétaro. Las siete cuencas se adaptaron exitosamente a los pacientes y fueron utilizadas para fabricar prótesis finales. Si bien el método de molde-digitalización tuvo ventajas clínicas sobre el método de medición, el transporte de moldes, el costo de digitalizarlos y la disminución en la portabilidad del sistema podría reducir su eficiencia en zonas de difícil acceso en México. Resumiendo, este estudio piloto confirmó la utilidad de la tecnología CAD/CAM para la fabricación central de cuencas protésicas en México