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

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 exoskeleton footwear on joint angular motion during walking in patients with peripheral artery disease

Gait, Lower Extremity, Peripheral Artery Disease, Joint Angle, Exoskeleton Footwear, Exoskeleton, Assistive Device, Walking

Increased minimum toe clearance variability in patients with peripheral arterial disease

Individuals with peripheral arterial disease (PAD) report difficulty walking and experience 73% more falls than their healthy counterparts, but no studies have investigated functional mechanisms contributing to increased falls. Minimum toe clearance (MTC) is the minimum vertical distance between the toe of the swinging leg and the walking surface when the leg is swinging, and decreased values are associated with an increased risk for falls. This study is the first such analysis in patients with PAD. Eighteen individuals with PAD and eighteen healthy controls walked on a treadmill before and after the onset of claudication pain. Mean MTC and the standard deviation of MTC values across the trial were calculated. Mean MTC was not different between groups in the pain-free (P = 0.244) or pain conditions (P = 0.565). MTC variability was increased for patients with PAD in pain-free (P = 0.048) and pain conditions (P = 0.019). No significant differences existed between conditions for MTC mean (P = 0.134) or MTC variability (P = 0.123). Increased MTC variability is present before and after the onset of claudication pain, and may be a useful assessment for treatment and rehabilitation efficacy in these patients

Peripheral Arterial Disease Affects the Frequency Response of Ground Reaction Forces During Walking

Background—Walking is problematic for patients with Peripheral Arterial Disease. The purpose of this study was to investigate the frequency domain of the ground reaction forces during walking to further elucidate the ambulatory impairment of these patients. Methods—Nineteen bilateral peripheral arterial disease patients and nineteen controls were included in this study. Subjects were matched for age and gait speed. Participants walked over a force plate sampling at 600Hz. PAD patients were tested before (pain-free condition) after the onset of claudication symptoms (pain). We calculated median frequency, frequency bandwidth, and frequency containing 99.5% of the signal for the vertical and anterior-posterior ground reaction forces. Findings—Our results showed reduced median frequency in the vertical and anterior-posterior components of the ground reaction forces between the control group and both peripheral arterial disease conditions. We found reduced frequency bandwidth in the anterior-posterior direction between controls and the peripheral arterial disease pain-free condition. There were no differences in median frequency or bandwidth between peripheral arterial disease pain-free and pain conditions, but an increase in the frequency content for 99.5% of the signal was observed in the pain condition. Interpretation—Reduced frequency phenomena during gait in peripheral arterial disease patients compared to velocity-matched controls suggests more sluggish activity within the neuromotor system. Increased frequency phenomena due to pain in these patients suggests a more erratic application of propulsive forces when walking. Frequency domain analysis thus offers new insights into the gait impairments associated with this patient population

Changes in ankle muscle force and power during walking in patients with peripheral artery disease

Background: Patients with peripheral artery disease (PAD) have significantly reduced lower extremity muscle strength compared with healthy individuals as measured during isolated, single plane joint motion by isometric and isokinetic strength dynamometers. The objective of this study was to understand the contribution of the ankle muscles during walking in patients with PAD and compared to healthy older individuals. Methods: A total of 12 patients diagnosed with Fontaine stage II PAD and 10 healthy older controls were recruited for the study. Each subject walked across a 10-meter pathway with reflective markers placed on specific anatomical locations on lower limbs while the marker coordinates were recorded using a 12-high speed infrared camera system. Gait simulations were performed in OpenSim software (version 4.0). The muscle force and power for individual muscles at ankle and as a group of ankle plantar flexor muscles were exported from OpenSim. Results: There was a significant reduction in ankle muscle power in patients with PAD during propulsion phase (p \u3c 0.05). There were significant reductions in lateral and medial gastrocnemius muscle forces and power during propulsion in patients with PAD (p \u3c 0.05). However, soleus muscle force and power were not altered during stance phase. Conclusions: Our simulation findings identified important information about PAD gait mechanics, specifically altered ankle muscle force and power contribution during stance phase