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Current Projects

 Multi-direction Reach Robot

Many patients with brain injury from cerebral palsy, stroke, and other diseases experience debilitating loss of upper extremity function. We are designing a portable robotic device to assist in therapeutic exercises to restore arm function for planar reaching movements supplemented with visual and auditory feedback. The device is expected to provide scalable resistance during arm motion. Patients will grasp a simple handle that is mechanically restricted to move within a 2D plane, and allow them to make reaching movements along desired trajectories during training. To increase the therapeutic effect, a programmable resistance will be applied according to the patients functional ability, providing low resistance to weak patients and higher resistance to stronger patients. Additionally, this resistance is directional; that is, motions in certain directions can be made easy, whereas motions in other directions are made harder. To perform reaching in a functional manner (i.e., against gravity), the entire device can be tilted and adjusted in height. To enrich sensorimotor experience, the design will also include sensors to detect endpoint trajectory in space (which will assist in providing visual feedback and also to track movement performance) and auditory cuing to facilitate temporal coordination.

Background: Physical rehabilitation constitutes an important component of recovery in these individuals. While there is mounting evidence to suggest that the magnitude of therapy dosage is directly related to recovery, conventional therapy with a therapist is often limited to a few hours in a week. Using robotic devices as therapy enhancers can thus significantly benefit individuals with neurological disorders and could become transformative to the field of rehabilitation science.


Leg Motor Skill Learning after Stroke


Stroke is a major cause of adult disability in the United States. Gait impairment is one of the primary causes of disability after stroke with about 75% of stroke survivors living with some form of gait dysfunction. 
Gait disruption not only creates a stigma for these patients, but also puts them at risk for fall-related injuries
and significantly impacts their quality of life. Unfortunately, current rehabilitation approaches are not sufficient to induce significant improvements beyond those achieved through natural biological recovery. Our long-term goal is to develop new methods to improve post-stroke gait function. An important first step in this process is to improve our current understanding of the motor learning deficits that occur after stroke. Existing research suggests that the same processes involved in learning a new skill may also contribute for recovery of functions after stroke. While the ability of an individual to learn a new skill has been well studied in the arm and hand muscles, there is little research on the leg muscles. The purpose of this study is to determine whether or not there are differences in skill learning using leg muscles between stroke survivors and a group of neurologically intact adults. Subjects will practice a target-tracking task with their leg while walking in a gait training device called as the Lokomat. Motor learning deficits will be quantified by measuring the magnitude of error in target-tracking and comparing the results with a group of uninjured control subjects. Retention tests will be performed on separate days to quantify both short-term and long-term learning deficits. We expect that the knowledge generated will help in designing new methods to treat people with walking disability.


Portable Robot for Resistive Gait Training

Many patients with brain injury from cerebral palsy, stroke, and other diseases experience debilitating loss of gait (i.e., walking) function. A growing body of evidence suggests that muscle strength is a strong predictor of gait function. While several forms of assistive robots are available for gait training, there are not many robots that can provide resistance during gait training, which is important to improve muscle strength. Here, we are designing a portable resistive robotic device to help assist in restoring gait function. To increase the therapeutic effect, a programmable resistance to the leg muscles will be applied according to the patient’s functional ability, providing low resistance to weak patients and higher resistance to stronger patients. The device will also be portable and if possible wearable by the subject. Additionally, this resistance is directional; that is, motions in certain directions can be made easy, whereas motions in other directions are made harder. The design will also include sensors to detect joint angles and endpoint trajectory in space, which will assist in providing visual feedback and also to track movement performance to facilitate movement coordination.

 


Muscle Strength & Voluntary Activation after ACL Reconstruction


Severe quadriceps weakness develops rapidly after anterior cruciate ligament (ACL) injury and surgery. The recovery of quadriceps stre
ngth is often incomplete even years after surgery. Quadriceps strength deficits from 2% to 20% have been reported in subjects more than 2 years post-ACL surgery. While it is evident that quadriceps weakness is a common finding in people with ACL reconstruction, the underlying mechanisms for such weakness are currently unclear. Reports from people with acute ACL injury indicate that quadriceps atrophy and activation failure are the primary contributing factor for quadriceps weakness. Scientists have also suggested that an inability to completely activate the quadriceps muscle (i.e., voluntary activation failure) is a primary cause of chronic quadriceps weakness in people after ACL reconstruction. However, our previous research indicates that quadriceps weakness is primarily related to peripheral changes in the quadriceps muscle (i.e., muscle atrophy) and not to levels of voluntary activation. We are currently performing an in-depth investigation of quadriceps muscle voluntary activation and its contribution to muscle weakness and function after ACL reconstruction.



Cardiometabolic & Neuromuscular Health Profiles in Adults with Cerebral Palsy


Over the past few years there has been greater awareness of the unique problems facing children with cerebral palsy (CP) as they transition to adulthood. The brain insult or structural malformation that causes CP does not progress with time, and yet adults with CP are subject to a number of secondary conditions that interfere with important aspects of quality of life, such as independence, participation, and employment. Premature declines in function among adults with CP may occur as a result of early and accelerated weakness, beyond that which is expected for adults in the general population. While the specific mechanisms of secondary muscle pathology and related comorbidities are not well defined, ample evidence does exist to confirm that individuals with CP have lower fitness, less muscle mass, neuromuscular inefficiency, and significantly reduced functional reserve. This ongoing circular series of events leads to a debilitating loss of physical mobility and muscle morphology, as well as a potentially exaggerated risk for obesity and cardiometabolic disease. Recent data suggests that overweight/obese adolescents with CP have a higher prevalence of dyslipidemia, hypertension, fatigue, and early maturation; however, this has yet to be studied in adults. More importantly, there is virtually no research regarding the simultaneous cardiometabolic and neuromuscular comorbidities facing individuals with CP throughout the lifespan. In collaboration with Dr. Mark Peterson, we are currently examining the adult CP phenotype in an effort to distinguish the unique neuromuscular and cardiometabolic profiles from those of typically developing adults.


 
Nurse-Driven Mobility Intervention (PORT Project)

Increasing mobility during an acute care hospitalization is extremely critical for the overall health and well being of an individual. A growing body of evidence supports the safety and feasibility of “early mobility” in the intensive care units (ICU) and suggests that increased activity decreases hospital length of stay and improves functional outcomes. Despite evidence on the benefits of mobility, physical activity decreases substantially when patients transfer from an ICU focused on “early mobility” to a general medicine ward, indicating a lack of sustainability of a mobility intervention in a general medicine ward. Sadly, while a number of studies have demonstrated the value of “early mobility” in the ICU setting, there has been little research addressing barriers, feasibility, and specific pathways which would lead to an increase in mobility on a general medicine floor. Therefore, the overall goal of this study is to identify barriers that may impact our ability to implement and maintain a mobility program, develop a tool for nurses to use to classify a patient’s functional mobility, and test the feasibility and benefits of executing a mobility protocol. We seek to achieve this by pursuing the following specific aims: 1) Identifying the existing barriers that negatively affect the nurses’ ability to mobilize patients through an online survey for nursing staff at large academic medical centers, 2) Developing a nurse-driven mobility algorithm to tier patients and examining whether the implementation of this algorithm improves the nurses’ ability to accurately identify a patient’s level of functional mobility, and 3) Determining the feasibility and functional benefits of delivering nurse-driven mobility interventions on a general medicine floor. We anticipate that successful completion of the proposed aims will provide a feasible, effective, and sustainable approach to improve physical activity and mobility for general medicine patients.