A Novel Tilted-Plane Ergometer System for Subject-Specific Rehabilitation.

Immobilization due to various reasons can lead to disuse muscle atrophy. If prolonged, the circumstance is exacerbated and may lead to joint contracture, dysfunction, and long-term sequela. Thus, a balanced exercise regimen is crucial. While able-bodied individuals can perform a variety of exercises, bedridden patients typically resort to exercising primarily with bicycle ergometers. However, since the pedaling trajectory with ergometers is confined to the sagittal plane, muscles responsible for medial-lateral movement and balance are not effectively trained. Furthermore, the direction of joint reaction forces, which is crucial for specific patients with ligament injuries, recurrent dislocations, and medial osteoarthritis, is not well facilitated. Thus, it would be beneficial for patients without full body weight support ability to train ab-/ad-ductor muscles by altering the direction of extrinsic load via ergometers. In this study, we present a novel Tilted-Plane Ergometer and proof-of-concept experiment with one healthy subject. The results suggest that subtle changes in ergometer configurations lead to different movements, joint alignments, and muscle recruitment patterns.

Investigation with able-bodied subjects suggests Myosuit may potentially serve as a stair ascent training robot.

Real world settings are seldomly just composed of level surfaces and stairs are frequently encountered in daily life. Unfortunately, ~ 90% of the elderly population use some sort of compensation pattern in order to negotiate stairs. Because the biomechanics required to successfully ascend stairs is significantly different from level walking, an independent training protocol is warranted. Here, we present as a preliminary investigation with 11 able-bodied subjects, prior to clinical trials, whether Myosuit could potentially serve as a stair ascent training robot. Myosuit is a soft wearable exosuit that was designed to assist the user via hip and knee extension during the early stance phase. We hypothesized that clinical studies could be carried out if the lower limb kinematics, sensory feedback via plantar force, and electromyography (EMG) patterns do not deviate from the user's physiological stair ascent patterns while reducing hip and knee extensor demand. Our results suggest that Myosuit conserves the user's physiological kinematic and plantar force patterns. Moreover, we observe approximately 20% and 30% decrease in gluteus maximus and vastus medialis EMG levels in the pull up phase, respectively. Collectively, Myosuit reduces the hip and knee extensor demand during stair ascent without any introduction of significant compensation patterns.

Biomechanical Analysis Suggests Myosuit Reduces Knee Extensor Demand during Level and Incline Gait.

An FDA-approved soft wearable robot, the Myosuit, which was designed to provide hip and knee extension torque has recently been commercialized. While studies have reported reductions in metabolic costs, increased gait speeds, and improvements in clinical test scores, a comprehensive analysis of electromyography (EMG) signals and joint kinematics is warranted because the recruitment of appropriate muscle groups during physiological movement patterns facilitates effective motor learning. Here, we compared the lower limb joint kinematics and EMG patterns while wearing the Myosuit with that of unassisted conditions when performing level overground and incline treadmill gait. The level overground gait sessions (seven healthy subjects) were performed at self-selected speeds and the incline treadmill gait sessions (four healthy subjects) were performed at 2, 3, 4, and 5 km/h. In order to evaluate how the user is assisted, we conducted a biomechanical analysis according to the three major gait tasks: weight acceptance (WA), single-limb support, and limb advancement. The results from the gait sessions suggest that Myosuit not only well preserves the users' natural patterns, but more importantly reduce knee extensor demand during the WA phase for both level and incline gait.

A smart insole system capable of identifying proper heel raise posture for chronic ankle instability rehabilitation.

Heel raise is widely prescribed to patients with chronic ankle instability in order to strengthen the Peroneus Longus muscle (PL) which supports the weakened lateral collateral ligaments. While the exercise itself is intuitive, ankle orientation is of particular importance because heel raises performed with inversion do not well recruit the PL. This implies that proper execution is imperative and a means to assess heel raise training sessions is needed. In this study we present a smart insole system capable of identifying heel raise events and its corresponding rise, hold and drop phases, which allows for a more descriptive analysis. The results from our heel raise sessions, which consist of four different variants performed by five healthy subjects, suggest that medial-lateral foot pressure distribution and foot orientation are needed to differentiate heel raises performed with ankle eversion and inversion. We go further and substantiate that proper execution, detected by our system, indeed leads to increased PL activation by analyzing the electromyography signals. We believe that the proposed system may provide clinicians with invaluable information regarding onsite as well as at-home training and possibly, with biofeedback, serve as foundation for software as a medical device.

Synthesis and Characterization of Activated Carbon Fibers Derived from Linear Low-Density Polyethylene Fibers Stabilized at a Low Temperature.

In this study, activated carbon fibers (ACFs) were prepared using a new method from polyethylene (PE) fibers. The stabilizing (or crosslinking) process of PE, an essential step, was achieved through a hybrid treatment using electron-beam/sulfuric acid at 110 °C that was more effective than the traditional method of using sulfuric acid at 180 °C for polyolefin. The stabilized precursor was then carbonized at 700 °C and activated at 900 °C with different activation times. The structural characteristics and morphologies of these ACFs were observed using an X-ray diffractometer and a field-emission scanning electron microscope, respectively. In addition, the N2/77K adsorption isotherm was used to discern textural properties. The total pore volume and specific surface area of these ACFs were found to be increased with a longer activation time, reaching final values of 0.99 cm3/g and 1750 m2/g, respectively. These ACFs also exhibited a high mesopore volume ratio (39%) according to crosslinking and crystallite formation conditions.

Carbon Fibers from High-Density Polyethylene Using a Hybrid Cross-Linking Technique.

In this study, a method for manufacturing high-density polyethylene (HDPE)-based carbon fibers using a hybrid cross-linking method was studied. HDPE precursor fibers were first cross-linked with an electron beam (E-beam) at an irradiation dose of 1000-2500 kGy, and then cross-linked in sulfuric acid at 80-110 °C for 60 min. Hybrid crosslinked fibers were carbonized for 5 min at a temperature of 900 °C. As a result, the hybrid crosslinked fibers had a carbonization yield of 40%. In addition, the carbonized fibers after hybrid crosslinking exhibited perfect fiber morphology, and HDPE-based carbon fibers with (002) and (10l) peaks, which are the intrinsic XRD peaks of carbon fibers, were successfully prepared.

Mapping of acetabular posterior wall fractures using a three-dimensional virtual reconstruction software.

INTRODUCTION: The aim of this study was to analyze and describe the fracture patterns of the acetabular posterior wall based on quantitative measurements of the fracture characteristics. MATERIALS AND METHODS: Computed tomography images of 51 patients with acetabular posterior wall fractures from an initial cohort of 216 acetabular fractures were imported into a three-dimensional (3D) virtual software. The reconstructed 3D images were utilized to evaluate the following: (i) fracture line mapping on the inner articular and retro-acetabular surfaces, (ii) common zones of fracture and marginal impaction, and (iii) categorization by location and pattern of comminution. The clock-face position was applied for description: the midpoint of the transverse acetabular ligament served as the +180° reference point, and the 0° reference point was set perpendicular to the ligament. The fracture angle on the articular surface was defined as the intersection between the start and end points. The fracture span on the retro-acetabular surface was defined as the ratio of the perpendicular distance, which is between the fracture beak and acetabular rim, to the entire length, which is from the edge to the rim. Quantitative measurements were performed, and the fracture patterns were analyzed. A color scale bar was used to visualize the common and marginal impaction zones. RESULTS: The articular surface mapping of all the cases demonstrated that the average starting point of the fracture line was +6.2° (±12.8°) and the endpoint was 96.7° (±13.3°), and the average fracture angle was 119.6° (±7.6°) with 80.6% of the fragments having angles within 18.7-117°. The retro-acetabular surface mapping demonstrated that the average fracture span was 0.65 ±0.20, and 61.7 % of the fracture lines were located within 0.6 to 0.9. Marginal impaction was found in 21 cases (21/51, 41.2%; range: between +7° and +105°). CONCLUSION: The fracture maps showed fracture patterns and recurrent fracture zones on the articular and retro-acetabular surfaces. However, there was no remarkable pattern of marginal impaction. LEVEL OF EVIDENCE: Retrospective cohort study.

Effect of Leukocyte-Rich and Platelet-Rich Plasma on Healing of a Horizontal Medial Meniscus Tear in a Rabbit Model.

There are limited reports on the effect of platelet-rich plasma (PRP) on meniscus healing. The purpose of this study was to investigate the effect of leukocyte-rich PRP (L-PRP) on potential healing of the horizontal medial meniscus tears in a rabbit model. A horizontal medial meniscus tear was created in both knees of nine skeletally mature adult rabbits. Left or right knees were randomly assigned to a L-PRP group, or a control group. 0.5 mL of L-PRP from 10 mL of each rabbit's whole blood was prepared and injected into the horizontal tears in a L-PRP group. None was applied to the horizontal tears in a control group. The histological assessment of meniscus healing was performed at two, four, and six weeks after surgery. We found that there were no significant differences of quantitative histologic scoring between two groups at 2, 4, and 6 weeks after surgery (p > 0.05). This study failed to show the positive effect of single injection of L-PRP on enhancing healing of the horizontal medial meniscus tears in a rabbit model. Single injection of L-PRP into horizontal meniscus tears may not effectively enhance healing of horizontal medial meniscus tears.