Articulated Ankle Foot Research Articles

The effect of articulated AFO with hydra pneumatic damper in biomechanical characteristic of drop foot: A pilot study.

Background: Ankle Foot Orthosis (AFOs) are frequently prescribed in the management of drop-foot patients. However, few studies have examined the benefits of different design of Ankle Foot Orthosis with extra elements like dampers or springs. Therefore, the objective of this study was to investigate the efficacy of articulated Ankle Foot Orthosis with Hydra pneumatic damper, in kinetic, kinematic and spatiotemporal parameters of drop foot patients. Methods: Ten drop foot patients were recruited for this study, walked at self-selected comfortable speed. A three-dimensional motion analysis, were used for obtaining kinetic, spatio-temporal and kinematic gait parameters. Results: The articulated Ankle Foot Orthosis with Hydra pneumatic damper was significantly improved speed, cadence, step length of walking (p<0.005). Furthermore, the peak and mean of moment, push off velocity and energy storing/returning were significantly improved by articulated Ankle Foot Orthosis with Hydra pneumatic damper (p<0.005). Conclusion: The newly designed articulated Ankle Foot Orthosis with Hydra pneumatic damper improved the ankle moment in at the loading response, power generation and the ankle range in drop foot patient.

Design and Evaluation of an Articulated Ankle Foot Orthosis with Plantarflexion Resistance on the Gait: a Case Series of 2 Patients with Hemiplegia.

Ankle-foot orthoses (AFOs) have been described to have positive effects on the gait biomechanics in stroke patients. The plantarflexion resistance of an AFO is considered important for hemiplegic patients, but the evidence is still limited. The purpose of this case series was to design and evaluate the immediate effect of an articulated AFO on kinematics and kinetics of lower-limb joints in stroke patients. The articulated AFO with the adjustment of plantarflexion resistance was designed. The spring generates a plantarflexion resistance of the ankle joint at initial stance phase. The efficacy of orthosis was evaluated on two stroke patients in 2 conditions: without an AFO and with the AFO. Results showed the immediate improvements for walking speed, stride length and angular changes of dorsiflexion of the paretic ankle joint during a gait cycle of both subjects using the AFO compared with barefoot walking. The AFO also was able to reduce the paretic knee extension in the single-support phase of the stance and increase the vertical COM displacement during stance phase on the affected leg. In conclusion, the designed AFO affect not only the movement of the ankle joint but also the movements of the knee joint and the vertical COM height. These changes indicate improvement of the first and the second rockers and swing phase gait but not third rocker function. Further investigation is recently underway to compare its effect compared with other AFOs on the gait parameters of hemiplegic patients.

An articulated ankle–foot orthosis with adjustable plantarflexion resistance, dorsiflexion resistance and alignment: A pilot study on mechanical properties and effects on stroke hemiparetic gait

Mechanical properties of an articulated ankle–foot orthosis (AFO) are closely related to gait performance in individuals post-stroke. This paper presents a pilot study on the mechanical properties of a novel articulated AFO with adjustable plantarflexion resistance, dorsiflexion resistance and alignment, and its effect on ankle and knee joint kinematics and kinetics in an individual post-stroke during gait. The mechanical properties of the AFO were quantified. Gait analysis was performed using a 3D motion capture system with a split-belt instrumented treadmill under 12 different settings of the mechanical properties of the AFO [i.e. 4 plantarflexion resistances (P1<P4), 4 dorsiflexion resistances (D1<D4), 4 initial alignments (A1<A4)]. The AFO demonstrated systematic changes in moment–angle relationship in response to changes in AFO joint settings. The gait analysis demonstrated that the ankle and knee angle and moment were responsive to changes in the AFO joint settings. Mean ankle angle at initial contact changed from −0.86° (P1) to 0.91° (P4) and from −1.48° (A1) to 4.45° (A4), while mean peak dorsiflexion angle changed from 12.01° (D1) to 6.40° (D4) at mid-stance. The novel articulated AFO appeared effective in influencing lower-limb joint kinematics and kinetics of gait in the individual post-stroke.

Beneficial effects of ankle–foot orthosis daytime use on the gait of Duchenne muscular dystrophy patients

BackgroundOrthosis use prevents muscle contracture and prolongs ambulation in patients with Duchenne muscular dystrophy (DMD). However, its biomechanical effects on gait are unclear. This study assessed the effects of daytime and night-time use of Articulated Ankle Foot Orthosis (AFO) on kinematic, kinetic and spatial/temporal gait parameters of DMD patients. MethodsTwenty ambulatory patients (4–12years of age) were assigned to one of three groups: no orthosis (NoO; n=7), night-time orthosis (NiO; n=7), day-time orthosis (DO; n=6). All subjects were evaluated once (Ev1) and five of them were re-evaluated between five and seven months after Ev1 (Ev2). FindingsCross-sectional analysis with linear mixed-effects models (ANOVA) showed increased peak dorsiflexion angle and dorsiflexor moment and decreased plantar flexion angle and ankle joint power generation for the DOwith group when compared to the NoO group (P<0.05). The DOwith group also showed decreased peak hip flexion angle, hip power absorption, plantar flexion angle and increased peak dorsiflexion moment when compared to the NoO group (P<0.05). Analysis of gait cycle curves showed significant and clinically relevant changes in kinematic and kinetic parameters for the DOwith group when compared to the other experimental groups. Longitudinal analysis suggest that night-time use of Articulated AFO can promote positive changes in gait parameters of DMD patients, when used before the functional deficit is too advanced. InterpretationEarly daytime and night-time use of Articulated AFO changed gait and minimized typical compensations seen in DMD patients, thus it is recommended in order to prolong gait ability.

Direct measurement of plantarflexion resistive moments and angular positions of an articulated ankle-foot orthosis while walking in individuals post stroke: A preliminary study.

The plantarflexion resistive moments of an articulated ankle–foot orthosis play an important role in improving gait in individuals post stroke. However, the evidence regarding their magnitude required from the articulated ankle–foot orthosis to improve walking is still limited. Therefore, the primary aim of this study was to directly measure the plantarflexion resistive moments and the joint angular positions while walking using a prototype instrumented articulated ankle–foot orthosis in five individuals post stroke. The secondary aim was to investigate their moment–angle relationship by changing its preset plantarflexion stiffness. Each subject was fitted with the instrumented articulated ankle–foot orthosis and walked on a treadmill under four different preset plantarflexion stiffness conditions (0.35 N·m/°, 0.51 N·m/°, 0.87 N·m/°, and 1.27 N·m/°). For each subject, the plantarflexion resistive moments and the joint angular positions of five continuous gait cycles were extracted and averaged for each condition. Data were plotted and presented as case series. Both plantarflexion resistive moments and joint angular positions of the ankle–foot orthosis changed according to the preset plantarflexion stiffness in all subjects. Using the instrumented articulated ankle–foot orthosis could potentially advance the understanding of the biomechanics of an ankle–foot orthosis, as well as contribute to more evidence-based orthotic care of patients.

The effect of changing plantarflexion resistive moment of an articulated ankle–foot orthosis on ankle and knee joint angles and moments while walking in patients post stroke

BackgroundThe adjustment of plantarflexion resistive moment of an articulated ankle–foot orthosis is considered important in patients post stroke, but the evidence is still limited. Therefore, the aim of this study was to investigate the effect of changing the plantarflexion resistive moment of an articulated ankle–foot orthosis on ankle and knee joint angles and moments in patients post stroke. MethodsGait analysis was performed on 10 subjects post stroke under four different plantarflexion resistive moment conditions using a newly designed articulated ankle–foot orthosis. Data were recorded using a Bertec split-belt instrumented treadmill in a 3-dimensional motion analysis laboratory. FindingsThe ankle and knee sagittal joint angles and moments were significantly affected by the amount of plantarflexion resistive moment of the ankle–foot orthosis. Increasing the plantarflexion resistive moment of the ankle–foot orthosis induced significant decreases both in the peak ankle plantarflexion angle (P<0.01) and the peak knee extension angle (P<0.05). Also, the increase induced significant increases in the internal dorsiflexion moment of the ankle joint (P<0.01) and significantly decreased the internal flexion moment of the knee joint (P<0.01). InterpretationThese results suggest an important link between the kinematic/kinetic parameters of the lower-limb joints and the plantarflexion resistive moment of an articulated ankle–foot orthosis. A future study should be performed to clarify their relationship further so that the practitioners may be able to use these parameters as objective data to determine an optimal plantarflexion resistive moment of an articulated ankle–foot orthosis for improved orthotic care in individual patients.

Virtual prototyping of a semi-active transfemoral prosthetic leg

This article presents a virtual prototyping study of a semi-active lower limb prosthesis to improve the functionality of an amputee during prosthesis-environment interaction for level ground walking. Articulated ankle-foot prosthesis and a single-axis semi-active prosthetic knee with active and passive operating modes were considered. Data for level ground walking were collected using a photogrammetric method in order to develop a base-line simulation model and with the hip kinematics input to verify the proposed design. The simulated results show that the semi-active lower limb prosthesis is able to move efficiently in passive mode, and the activation time of the knee actuator can be reduced by approximately 50%. Therefore, this semi-active system has the potential to reduce the energy consumption of the actuators required during level ground walking and requires less compensation from the amputee due to lower deviation of the vertical excursion of body centre of mass.

Mechanism and design analysis of articulated ankle foot orthoses for drop-foot.

Robotic technologies are being employed increasingly in the treatment of lower limb disabilities. Individuals suffering from stroke and other neurological disorders often experience inadequate dorsiflexion during swing phase of the gait cycle due to dorsiflexor muscle weakness. This type of pathological gait, mostly known as drop-foot gait, has two major complications, foot-slap during loading response and toe-drag during swing. Ankle foot orthotic (AFO) devices are mostly prescribed to resolve these complications. Existing AFOs are designed with or without articulated joint with various motion control elements like springs, dampers, four-bar mechanism, series elastic actuator, and so forth. This paper examines various AFO designs for drop-foot, discusses the mechanism, and identifies limitations and remaining design challenges. Along with two commercially available AFOs some designs possess promising prospective to be used as daily-wear device. However, the design and mechanism of AFO must ensure compactness, light weight, low noise, and high efficiency. These entailments present significant engineering challenges to develop a new design with wide consumer adoption.

Stage I and II Posterior Tibial Tendon Dysfunction Treated by a Structured Nonoperative Management Protocol: An Orthosis and Exercise Program

Posterior tibial tendon dysfunction (PTTD) is a relatively common problem of middle-aged adults that usually is treated operatively. The purpose of this study was to identify strength deficits with early stage PTTD and to assess the efficacy of a focused nonoperative treatment protocol. Forty-seven consecutive patients with stage I or II posterior tibial tendon dysfunction were treated by a structured nonoperative protocol. Criteria for inclusion were the presence of a palpable and painful posterior tibial tendon, with or without swelling and 2) movement of the tendon with passive and active nonweightbearing clinical examination. The rehabilitation protocol included the use of a short, articulated ankle foot orthosis or foot orthosis, high-repetition exercises, aggressive plantarflexion activities, and an aggressive high-repetition home exercise program that included gastrocsoleus tendon stretching. Isokinetic evaluations were done before and after therapy to compare inversion, eversion, plantarflexion, and dorsiflexion strength in the involved and uninvolved extremities. Criteria for successful rehabilitation were no more than 10% strength deficit, ability to perform 50 single-support heel rises with minimal or no pain, ability to ambulate 100 feet on the toes with minimal or no pain, and ability to tolerate 200 repetitions of the home exercises for each muscle group. Before therapy weakness for concentric and eccentric contractures of all muscle groups of the involved ankle was significant (p<0.001). After a median of 10 physical therapy visits over a median period of 4 months, 39 (83%) of the 47 patients had successful subjective and functional outcomes, and 42 patients (89%) were satisfied. Five patients (11%) required surgery after failure of nonoperative treatment. This study suggests that many patients with stage I and II posterior tibial tendon dysfunction can be effectively treated nonoperatively with an orthosis and structured exercises.

17.26 Analysis of spasticity on medial gastrocnemius instroke individuals wearing articulated ankle—foot orthoses during ambulation

It is unclear whether the combined effects of exercise and nutrition are better than those of exercise alone or nutrition alone in older adults with sarcopenia. This paper assesses the comparative effects of exercise, nutrition, and the combination of exercise and nutrition on muscle mass, muscle strength, and physical performance in older adults with sarcopenia. In this systematic review and network meta-analysis, 11 electronic databases were searched up to November 2020. Inclusion criteria were: (1) adults aged 65 years and older with sarcopenia; (2) interventions of exercise, nutrition, or the combination of both; (3) the outcomes include at least one of the following: muscle mass, muscle strength (hand grip and knee extension strength), or physical performance (gait speed and dynamic balance); and (4) randomized control trials. For each outcome measurement, a network meta-analysis was conducted to determine the direct and indirect effects of each intervention compared with each of the other interventions. A total of 26 studies were included in the network meta-analysis. Compared with the control group, exercise alone and the combination of exercise and nutrition significantly increased handgrip strength (1.12 kg, 95% CI: 0.12, 2.11; 2.03 kg, 95% CI: 1.10, 2.97) and improved dynamic balance (-1.76 seconds, 95% CI: -2.24, -1.28; -1.02 seconds, 95% CI: -1.64, -0.39). Both exercise alone and the combination of exercise and nutrition have beneficial effects on muscle strength and physical performance in older adults with sarcopenia.

Postoperative discitis due to Propionibacterium acnes: a case report and review of the literature

Background No previous report has described a progressive, destructive postoperative discitis requiring operative stabilization due to Propionibacterium acnes. The clinical and radiographic features and treatment options associated with discitis due to P acnes are presented in a retrospective case study, as well as a review of the current literature. Case Description Seven weeks after a routine lumbar discectomy, the patient presented with clinical findings and radiographic imaging consistent with discitis. Intraoperative cultures obtained from irrigation and debridement of the disc space revealed P acnes, and appropriate intravenous antibiotic treatment was instituted. Approximately 2 months later, the patient showed progression to a destructive osteomyelitis requiring operative stabilization. Nine weeks after stabilization, the patient continued to have lower back pain without radiculopathy. Laboratory values had normalized. Radiographic imaging revealed good instrumentation positioning and adequate fusion. The patient was ambulatory with bilateral articulating ankle foot orthoses and a walker. Conclusion The reported case adds to the literature on postoperative discitis due to P acnes and demonstrates that this organism can occasionally be the cause of progressive, destructive osteomyelitis. In addition, we review the incidence, risk factors, and clinical course of discitis due to P acnes.

The effects of fixed versus articulated ankle foot orthoses on gait in subjects with cerebral palsy

The aim of the present study was to assess the effect of postural insoles on gait performance in children with Cerebral Palsy (CP). Twenty four children between four and 12 years of age were randomly allocated either the control group (n = 12) or experimental group (n = 12). The control group used placebo insoles and the experimental group used postural insoles. Three-dimensional gait analysis was performed under three conditions: barefoot, in shoes and in shoes with insoles. Three evaluations were carried out: 1)immediately following placement of the insoles; 2)after three months of insole use; and 3)one month after suspending insole use. Regarding the immediate effects and after three months use of insole, significant improvements in gait velocity and cadence were found in the experimental group, along with an increase in foot dorsiflexion, a reduction in knee flexion and a reduction in internal rotation. Conversely, these changes were not maintained in the third assessment, one month after withdrawal of the insoles. The use of postural insoles led to improvements in gait performance in children with CP.

Sequential weaning of an articulating ankle foot orthosis with a posterior check strap in the rehabilitation of a stroke victim: Sandra M. Ciccone, Cynthia A. Wertz, Fred Chen (Western Reserve Care Systems, Southside Medical Center Youngstown, OH)

Sequential weaning of an articulating ankle foot orthosis with a posterior check strap in the rehabilitation of a stroke victim: Sandra M. Ciccone, Cynthia A. Wertz, Fred Chen (Western Reserve Care Systems, Southside Medical Center Youngstown, OH)

A comparison of the effects of fixed versus articulated ankle foot orthoses on gait in subjects with cerebral palsy

A comparison of the effects of fixed versus articulated ankle foot orthoses on gait in subjects with cerebral palsy

The effects of solid and articulating ankle foot orthoses during sit-to-stand in young children with spastic diplegia

The effects of solid and articulating ankle foot orthoses during sit-to-stand in young children with spastic diplegia