Individuals with Peripheral Artery Disease Alter Spatiotemporal Gait Parameters When Walking With Pain versus Without Pain

This abstract compares the spatiotemporal walking parameters of individuals with peripheral artery disease at the time they first begin walking, the time when they first feel pain, and the time when they can no longer continue walking

Gait variability of patients with intermittent claudication is similar before and after the onset of claudication pain

Background Recent research demonstrated that intermittent claudication patients have increased gait variability prior to the onset of claudication. However, it is unknown if these patients experience additional gait adaptations after the onset of claudication. Thus, we sought to determine how gait variability is affected by claudication in an effort to contribute to improved clinical management. Methods Twenty-six intermittent claudication patients and 20 controls walked on a treadmill at self-selected speed; intermittent claudication patients were tested before (pain free) and after (pain) the onset of claudication. Variability of the ankle, knee, and hip joint angles was assessed using the largest Lyapunov exponent, standard deviation and coefficient of variation. Dependent t-tests were used to compare the pain free and pain conditions. Independent t-tests were used to compare intermittent claudication patients and controls. Findings Pain free and pain conditions were not significantly different for any of the parameters evaluated except the ankle. Compared to controls, patients had significantly greater values for the largest Lyapunov exponent in both conditions for all joints. Interpretation Gait variability was essentially the same before and after the onset of claudication at the knee and the hip, and was increased in both conditions compared to controls. This indicates altered cooperation between components of the locomotor system of intermittent claudication patients, likely due to the associated myopathy since differences were present even before the onset of claudication. This research helps provide essential biomechanical knowledge of intermittent claudication that contributes to improved clinical management

Superficial temporal artery aneurysms

AbstractObjective: We analyzed the data from our vascular registry to determine the cause, clinical features, and cost-effective management of this uncommon pathologic entity. Design: Patients referred to the vascular surgery outpatient clinic of a tertiary referral center during the past 18 years were evaluated. Subjects: The subjects were six male patients (14 to 32 years) referred for evaluation of a unilateral pulsatile mass over the temporal region of the head. Intervention: Diagnosis of superficial temporal artery aneurysm was verified by loss of the aneurysm's pulse with compression of the ipsilateral proximal superficial temporal artery. All treated aneurysms were electively ligated and excised as an ambulatory procedure. Results: The symptoms were resolved. No recurrences or other complications were seen. Conclusions: Although rare, a superficial temporal artery aneurysm should be considered when a temporal head mass is evaluated. This condition is almost always a result of blunt or penetrating head trauma. Clinical examination is sufficient to confirm the diagnosis. Simple elective ligation and excision of the aneurysm is curative. (J Vasc Surg 1998;27:374-7.

CONSIDERATIONS FOR IMPLEMENTING AN ANKLE FOOT ORTHOSIS TO IMPROVE MOBILITY IN PERIPHERAL ARTERY DISEASE

An ankle- foot orthosis (AFO) can contribute to push-off during walking by storing energy from heel strike in the rigid strut and subsequently returning force during push-off. Peripheral artery disease (PAD), a manifestation of systemic atherosclerosis, blocks the arteries supplying blood to the legs and causes muscle pain and weakness, which leads to difficulty walking. Wearing an AFO can help patients with PAD walk better. In our study, subjects decided whether to adopt or not adopt the AFO. Our goal is to assess early AFO intervention withdrawal (wAFO) and AFO intervention completion (cAFO). Participants (n=21) were recruited and consented to wear an AFO for three months. The subjects were assessed for early AFO intervention withdrawal (n=6) and completion (n=15). Semi-structured interviews were conducted, and data were analyzed using a summative content analysis approach. Only six of fourteen of cAFO subjects described their initial reactions to the AFO as negative versus three of six wAFO subjects. The wAFO group reported higher levels of physical discomfort with the use of the AFO (4/6 vs 7/15) and pre-existing health issues as a barrier to the use of the AFO (3/6 vs 5/15). Patients withdrawing prior to completion of the AFO intervention tended to have increased negative perceptions, comorbidities, and physical discomfort. Both groups reported positive aspects of the AFO such as ease in standing and walking. Subjects that consented to follow up after six months of AFO intervention answered semi-structured questionnaires and a survey based on the i-PARIHS framework

MUSCLE OXYGENATION IN PATIENTS WITH PERIPHERAL ARTERY DISEASE DURING WALKING WITH AND WITHOUT AN ANKLE FOOT ORTHOSIS

Peripheral artery disease (PAD) is a cardiovascular disease caused by blockages in the arteries that reduce blood flow to the peripheral limbs. Claudication, a prominent symptom of PAD is a condition in which the lack of blood flow causes an inability to meet the metabolic demands of the muscle tissue, causes severe cramping pain. Previous studies have shown muscle oxygenation starts significantly lower and declines faster in patients with PAD compared to healthy controls. An ankle foot orthosis (AFO) can provide walking assistance by absorbing and returning the mechanical force during walking. We hypothesized oxygenation levels would be higher in patients with PAD walking with the AFO. Our research included seven subjects with PAD, patients performed a standardized graded treadmill test until claudication pain made them stop for both the AFO and non-ankle foot orthosis condition (NAF). Muscle oxygenation values were recorded before, during and directly following the trials for both conditions. PAD patients using the AFO significantly improved muscle oxygenation in the calf muscles. Our study only included seven patients, larger trials will be needed to increase the statistical strength

COLLISION WORK PERFORMED BY PATIENTS WITH PERIPHERAL ARTERY DISEASE

The goal of this study was to assess the differences in collision work performed by healthy, aged-matched controls compared to patients with peripheral artery disease (PAD) to provide foundations for an eventual exoskeleton design. Collision work is energy dissipated into the surrounding environment from impact, in this study’s case, upon heel strike. When designing an exoskeleton for patients with PAD, harvesting energy lost to collision work could be a valuable mechanism to improve walking performance. Devices designed to utilize the normally dissipated energy for assisting propulsion to improve walking performance are under-explored [1, 2]. The purpose of this study was to assess the validity of healthy, older individuals as a model for patients with PAD when investigating collision work as a primary exoskeleton design consideration. References [1] Kuo, A., et al. (2005). Exerc. Sport Sci. Rev.,33: 88-97 [2] Li, Q., et al. (2009). J. Neuroeng. Rehabil., 6: 22-22 [3] Donelan, J., et al.(2002). A. D. J. Biomech., 35: 117-12

The effect of pharmacological treatment on gait biomechanics in peripheral arterial disease patients

<p>Abstract</p> <p>Background</p> <p>Pharmacological treatment has been advocated as a first line therapy for Peripheral Arterial Disease (PAD) patients suffering from intermittent claudication. Previous studies document the ability of pharmacological treatment to increase walking distances. However, the effect of pharmacological treatment on gait biomechanics in PAD patients has not been objectively evaluated as is common with other gait abnormalities.</p> <p>Methods</p> <p>Sixteen patients were prescribed an FDA approved drug (Pentoxifylline or Cilostazol) for the treatment of symptomatic PAD. Patients underwent baseline gait testing prior to medication use which consisted of acquisition of ground reaction forces and kinematics while walking in a pain free state. After three months of treatment, patients underwent repeat gait testing.</p> <p>Results</p> <p>Patients with symptomatic PAD had significant gait abnormalities at baseline during pain free walking as compared to healthy controls. However, pharmacological treatment did not produce any identifiable alterations on the biomechanics of gait of the PAD patients as revealed by the statistical comparisons performed between pre and post-treatment and between post-treatment and the healthy controls.</p> <p>Conclusions</p> <p>Pharmacological treatment did not result in statistically significant improvements in the gait biomechanics of patients with symptomatic PAD. Future studies will need to further explore different cohorts of patients that have shown to improve significantly their claudication distances and/or their muscle fiber morphology with the use of pharmacological treatment and determine if this is associated with an improvement in gait biomechanics. Using these methods we may distinguish the patients who benefit from pharmacotherapy and those who do not.</p

Metabolically efficient walking assistance using optimized timed forces at the waist

The metabolic rate of walking can be reduced by applying a constant forward force at the center of mass. It has been shown that the metabolically optimal constant force magnitude minimizes propulsion ground reaction force at the expense of increased braking. This led to the hypothesis that selectively assisting propulsion could lead to greater benefits. We used a robotic waist tether to evaluate the effects of forward forces with different timings and magnitudes. Here, we show that it is possible to reduce the metabolic rate of healthy participants by 48% with a greater efficiency ratio of metabolic cost reduction per unit of net aiding work compared with other assistive robots. This result was obtained using a sinusoidal force profile with peak timing during the middle of the double support. The same timing could also reduce the metabolic rate in patients with peripheral artery disease. A model explains that the optimal force profile accelerates the center of mass into the inverted pendulum movement during single support. Contrary to the hypothesis, the optimal force timing did not entirely coincide with propulsion. Within the field of wearable robotics, there is a trend to use devices to mimic biological torque or force profiles. Such bioinspired actuation can have relevant benefits; however, our results demonstrate that this is not necessarily optimal for reducing metabolic rate

Design and development of a semi-rigid hip exoskeleton to reduce metabolic cost

Robotic exoskeletons can reduce metabolic cost in healthy individuals and restore mobility in patients with peripheral artery disease (PAD). PAD is a cardiovascular disease produced by atherosclerosis of the leg arteries. The primary symptom of PAD is claudication or pain in the legs during walking, which severely shortens the distance a patient can walk. Knowing that up to 40% of the metabolic cost of walking comes from the hip muscles, different groups have been developing rigid exoskeletons and soft exosuits that assist the hip. Assisting at the hip has the advantage that the exoskeleton mass is positioned close to the center of mass, which minimizes the energy cost of the added mass. Soft exosuits have the advantage that they allow greater freedom of movement. However, soft exosuits often cannot apply the same torque magnitudes as rigid exoskeletons, and they rely on friction with the skin to remain anchored. The purpose of this work was to develop a semi-rigid hip exoskeleton that can connect to and be powered by an existing actuation unit, to address the limitations of current existing soft exosuits. We evaluated the device performance by analyzing the match between desired and actual torque applied to the hip joint. Our exoskeleton\u27s semi-rigid design introduces advantages in comfort and efficiency of control in patients with PAD because it requires less friction and compression than soft exosuits. Our initial work demonstrates a good match between the desired and actual torque that the exoskeleton was able to generate for each leg