Cara L. Lewis - US grants

[unreadable] DESCRIPTION (provided by applicant): Robotic devices have led to major advances in understanding the motor control of neurologically intact and neurologically impaired individuals. While many studies have used robotic devices to study upper limb motor adaptation and control, there are relatively few robotic devices for studying the lower limb. Ferris and colleagues have developed robotic lower limb orthosis to study motor adaptation during human locomotion. Initial studies indicate that humans can substantially adapt the timing and magnitude of lower limb muscle activation patterns to walk with near normal kinematics while being assisted by the robotic orthosis. The ability to use upper limbs to control lower limb robotic orthosis could greatly facilitate locomotor rehabilitation in individuals with neurological impairment. This novel control method would give the patient direct control over timing and magnitude of the robotic assistance. However, it is not known if humans can readily adapt upper limb muscle activity to effectively control lower limb robotic assistance during walking. Therefore, the overall objectives of the proposed research are to determine 1) if humans will modify upper limb muscle activity and/or movement during treadmill walking to control plantar flexion assistance from a robotic ankle-foot orthosis (AFO), and 2) if one controller allows the user to adapt faster or gain more assistance from the AFO than the other controllers. We will have healthy human subjects walk while wearing a robotic AFO powered by an artificial plantar flexor muscle controlled by the upper limb. We will test 3 different proportional control methods for the robotic AFO: myoelectric control using the triceps muscle, kinematic control using elbow extension, and a handheld pushbutton. Our primary variable will be net mechanical work done by the AFO during push-off. This will allow us to quantify how well the AFO can assist the subject during walking. We will also test for differences between controllers in terms of speed of motor adaptation. We will calculate motor adaptation period by the time required to reach steady state in: a) ankle kinematic correlation coefficient, b) orthosis positive work and c) orthosis negative work. To further characterize how subjects modify their muscle activation and/or movement, we will also analyze lower limb muscle activity, kinematics, and kinetics. The results of these studies could lead to better robotic interfaces for assisting gait rehabilitation after spinal cord injury, stroke, or other neurological impairments. [unreadable] Lay summary: The insight into the neural control of human locomotion and motor adaptation provided by this study may translate into innovative rehabilitation therapies and major advances in powered orthoses and prostheses for individuals with impaired mobility due to neurological injury or amputation. [unreadable] [unreadable] [unreadable] [unreadable]

DESCRIPTION (provided by applicant): Acetabular labral tears are an increasingly recognized source of hip pain in young adults, especially females, and have been linked to the premature development of hip osteoarthritis (OA). Recently, femoroacetabular impingement (FAI) has been implicated as a cause of labral injury and OA. In FAI, hip pain occurs in the presence of a structural abnormality of the acetabulum or femur which results in early contact between the bones during hip flexion and internal rotation. Current treatment for FAI includes surgical procedures to resect or reorient the femur or acetabulum or both. While structure does contribute to hip pain, increasing evidence suggests that movement patterns may also play an important role. The long-term goal of this line of research is to improve treatment for hip pain, especially in young adults, which will prevent or slow the progression of chondral damage and thereby reduce the need for hip arthroplasty. The purpose of this project is to assess the movement patterns of people with FAI compared to people without hip pain and to test for sex- and limb- specific differences in these patterns. Identification of differences in movement patterns which may contribute to hip pain can improve non-invasive treatment for people with hip pain. To test for these differences, we will assess movement patterns using kinematic data collected during movements including walking, stepping down, supine straight leg raise and prone hip extension on subjects with FAI and subjects without hip pain. We hypothesize that subjects with FAI will display movement patterns which are closer to their end-range hip motion than subjects without hip pain. We believe that these movement patterns contribute to a subject's hip pain. We also hypothesize that females with FAI will display different movement patterns than males with FAI. We anticipate this sex difference in movement patterns because there is an unequal distribution of the structural abnormalities among females and males, and because a sex effect has been noted in other lower extremity injuries (e.g. ACL tears, patellofemoral pain). Furthermore, as subjects often have unilateral pain despite bilateral structural abnormalities, we hypothesize that subjects with FAI will display different movement patterns of the painful hip than the unimpaired hip. The knowledge gained from this research has the potential to redirect treatment for people with FAI by identifying sex-specific movement patterns which could be targeted by inexpensive and non-invasive therapeutic interventions. It also could be used to develop prevention programs focused on neuromuscular retraining.

DESCRIPTION (provided by applicant): Effect of femoroacetabular impingement (FAI) on hip motion in young adults Femoroacetabular impingement (FAI) is an increasingly recognized source of hip pain in young adults and has been implicated as a cause of labral injury and hip osteoarthritis (OA). FAI is a structural abnormality of the acetabulum (pincer FAI) or femur (cam FAI) which results in impingement between the acetabulum and femur during hip flexion and internal rotation. Current treatment for FAI includes surgical procedures to resect or reorient the femur or acetabulum or both. The number of FAI surgeries being performed in the US is estimated at 50,000 per year, with an annual growth rate of 15%, indicating that FAI is a growing health concern. While structure does contribute to hip pain, increasing evidence suggests that movement patterns also play an important role. The overall goal of this line of research is to improve treatment for hip pain, especially in young adults, prevent or slow the progression of chondral damage, and reduce the need for hip arthroplasty. The purpose of this project is to assess the movement patterns of people with painful FAI compared to people without hip pain and to test for pathology-specific and limb-specific differences in these patterns Identification of differences in movement patterns which may contribute to hip pain can improve non- invasive treatment for people with hip pain. To test for these differences, we will assess movement patterns using kinematic data collected during tasks including walking, running, stepping down and up, single leg squat, supine straight leg raise and prone hip extension in subjects with painful FAI and subjects without hip pain. We hypothesize that subjects with painful FAI will display movement patterns which are closer to the end of their available range of hip flexion, adduction and internal rotation than subjects without hip pain. We believe that these movement patterns contribute to a subject's hip pain. Based on the distinct patterns of joint damage between the two types of FAI, we hypothesize that people with pincer FAI will display different movement patterns than people with cam FAI. The knowledge gained from this research has the potential to redirect treatment for people with FAI by identifying movement patterns that could be targeted by inexpensive and non- invasive therapeutic interventions such as neuromuscular retraining.

Title: Movement screening and modification in individuals with femoroacetabular impingement syndrome Femoroacetabular impingement syndrome (FAIS) is a newly recognized clinical in individuals presenting with hip pain along with structural hip morphology thought to contribute to premature contact between the proximal femur and acetabulum. While there is strong agreement among experts that FAIS is a movement-related disorder, it remains unclear how much of the problem is the altered morphology vs. the altered movement in presence of the morphology. Recent studies using 3D motion capture have demonstrated that individuals with FAIS perform functional movements with increased anterior pelvic tilt and hip flexion, placing the hip at greater risk of impingement. As these studies tested how one moves naturally, it remains unclear if these movement faults are modifiable with simple cues. The purpose of this study is to test typical movement patterns individuals with FAIS and determine if these patterns can be easily modified when given simple cues. To test this, we will have individuals with FAIS and matched healthy controls perform three movement tasks with no cues and with simple cues to correct movement faults. The presence of specific movement faults will be determined by experienced musculoskeletal viewing the recorded with 2D videos, shifting this work from the motion capture lab to the clinical setting. We hypothesize that individuals with FAIS will have more movement faults than individuals without FAIS. We also hypothesize that individuals with FAIS will correct a lower percentage of faults than individuals without FAIS. For individuals with FAIS, we also hypothesize that individuals who have less faults in their typical movement pattern and are more able to correct those faults will report better function and less pain than individuals with FAIS who have more faults or are less able to modify their movement faults. This project is a first step to understanding if people with FAIS can modify injurious movement patterns in a single session.