RESEARCH

Dr. Rudolph's research interest is lower extremity control of locomotion. She studies people with joint instability in anterior cruciate ligament deficient individuals and those with osteoarthritis of the knee, people with hemiparesis post-stroke and older adults. She is also interested in developing new technologies for use in rehabilitation including muscle strengthening devices and rehabilitation robots for gait training. Below are some brief descriptions of current and past research projects.

Experimental Bioengineering Research Grant (EBRG) (top)

Smart Knee Brace NIH R21 HD047468 9/1/04-8/31/06 Collaborators:  Sunil Agrawal, PhD Darcy Reisman, PhD, PT Greg Hicks, PhD, PT A vast number of people are affected by conditions that result in profound muscle weakness or impaired motor control that impede the ability to walk.  If motor function is completely lost, rehabilitation of walking function may be delayed until the patient is able move actively.

Delayed therapy often leads to secondary impairments that exacerbate a patient's functional losses such as disuse atrophy and general deconditioning.  Currently, therapists can begin rehabilitation of walking by using lower extremity braces or body weight supported treadmill training to support the weak limb.  No currently available lower extremity braces can provide the patient the experience of typical movement patterns; rather braces are designed to immobilze the limb on which the patient bears weight.  This fosters abnormal, inefficient and very energy costly movement patterns that might be difficult to overcome.  This project involves the development of a Smart Knee Brace (SKB) for use in rehabilitation of walking in persons with lower extremity weakness.  The purpose of this study is to develop the SKB that will help to control knee movement during the stance phase of gait by encouraging more normal movement patterns while allowing free knee motion during the swing phase, something no commercially available braces can do.  The SKB will provide control of the knee joint that will be adjusted for each patient based on his or her walking ability and the goals of their rehabilitation.  This study represented the first phase of the work to develop the SBK and its electronic controllers based on walking patterns from healthy older subjects.  Feasibility of the SKB will also be tested on healthy subjects and patients with hemiparesis from stroke.  The data collected during the proposed work will be used to plan future clinical phases of the work.

Bioengineering Research Grant (top)

Innovative Smart Brace Balance Training: Enhancement, Investigation, Application NIH R01HD058711-01 (Pending)
PI: Katherine Rudolph, PT, PhD
Collaborators: Sunil K. Agrawal, PhD, Greg Hicks, PT, PhD

The long term goal of the work is to develop training programs that will improve functional mobility in older adults at risk for falling. The current proposal presents methods to refine and improve the existing SB, and outlines studies designed to investigate the response of young, older adult subjects as well as older adults with a risk of falls to novel and creative SB paradigms. We will develop a mathematical model to predict subject responses to perturbations that will be useful in future training studies, and will complete a study of reactions to perturbation algorithms that might be used during a balance training program that will provide pilot data for a future randomized controlled clinical trial. The results of this study will provide insight into dynamic balance during walking and develop methods for a training program to improve dynamic balance and reduce the risk of falls in older adults.

Beginning Grant-In-aid (top)

Relationship between speed and walking function post-stroke (PI: Reisman)
7/1/07 – 6/30/09
American Heart Association

The Aims of this project are to: 1) understand the effects of systematic increases in walking speed on the walking pattern of persons with post-stroke hemiparesis and to understand how this is influenced by the level of walking impairment and 2) understand the effects of systematic increases in walking speed on the energy expenditure of persons with post-stroke hemiparesis and understand how this is influenced by the level of walking impairment. In the proposed studies, measurements of the walking pattern and energy expenditure will be taken at multiple speeds in groups of subjects with differing levels of impairment post-stroke to understand the relationship between speed, walking patterns and energy cost. The long term goal of this research is to develop scientifically based speed dependent treadmill training programs that improve walking speed, efficiency and ultimately, community participation in people with hemiparesis after stroke.

RESEARCH PARTNERSHIPS FOR IMPROVING FUNCTIONAL OUTCOMES (top)

Fast Treadmill Training & Functional Electrical Stimulation (fastFES) to Improve Walking Post-stroke (PI: Binder-Macleod)
9/12/07 – 5/31/12
NIH R01 NR010786
Collaborators: William Farquhar, PhD, Jill Higginson, PhD, Darcy Reisman, PT, PhD, Katherine Rudolph, PT, PhD

The overall goal of the project is to develop a physiologically based intervention to improve functional ambulation in individuals who have sustained a stroke. The Specific Aims are to: 1) develop and test a fast treadmill training and functional electrical stimulation (FastFES) intervention that improves the walking patterns and energy efficiency during treadmill -walking in individuals who have sustained a stroke, 2) develop and test a 12-week training protocol using FastFES to improve body structure and function in individuals who have sustained a stroke, and 3) demonstrate the feasibility and effects of FastFES training compared to traditional and Fast treadmill training on body structure and function, activity, and participation in individuals who have sustained a stroke. For more information please see the fastFES web site.

center for biomedical engineering research (COBRE) renewal (top)

Knee Stiffness, Proprioception and Instability affect Knee Control in OA (PI Rudolph)
COBRE Mentoring Women in Science and Engineering (WISE)
NIH P20 RR16458 (PI: Buchanan)
6/07 - 5/12
Collaborator: Charles (Buz) Swanik, PhD, ATC, Kurt Manal, PhD

The purpose of subproject 5 is to explore the influence of strength, proprioception, stiffness on knee stabilization strategies in people with medial knee osteoarthritis and determine what influence different stabilization strategies have on joint load. We will also investigate if people with self-reported knee instability are able to adapt their movement strategies in response to repeated exposure to a perturbation to the lower limb to determine if people with knee OA are able to adapt their neuromuscular control strategies similar to healthy individuals. The results of this study will help identify strategies that will be addressed in future studies of training interventions. Click here for Video of Perturbation.

PhD Dissertation (top)

The studies in this project represent a comprehensive evaluation of common characteristics of persons with medial knee OA and their impact on movement and muscle activation patterns. Subjects were studied walking on level ground and also when exposed to a lateral perturbation* that was intended to challenge knee stability in order to investigate muscle stabilization strategies in people in which the sensation of knee instability affected their daily activities and those who did not experience knee instability. The findings from these studies provide insight into knee stabilization strategies that will ultimately lead to the development of rehabilitation interventions with the goals of slowing the cycle of OA progression and maximizing the quality of life of people with OA. Click here for Video of the perturbation.

1. Schmitt LC, Fitzgerald GK, Reisman AS, Rudolph KS. ,Instability, Laxity, and Physical Function in Patients with Medial Knee Osteoarthritis. Phys Ther 2006; (in review)
2. Schmitt LC, Rudolph KS. Muscle Stabilization Strategies in People with Medial Knee Osteoarthritis: The Effect of Instability. J Orthop Res (in press)
3. Rudolph KS, Schmitt LC. Age-related changes in strength and walking patterns: Are they related to knee osteoarthritis?. Phys Ther Phys Ther. 2007 Sep 4. [Epub ahead of print].
4. Schmitt LC, Rudolph KS. Influences on Knee Movement Strategies during Walking in Persons with Medial Knee Osteoarthritis. Arthritis Rheum 2007, Jul 30;57(6):1018-1026.

Center for biomedical engineering Research (COBRE) (top)

Knee Alignment and the Progression of Osteoarthritis (PI: Rudolph)
COBRE: Osteoarthritis: Prevention and Treatment (PI Buchanan)
National Institutes of Health  P20RR016458
(23feb02 - 30jun06) 
Collaborators:  Lynn Snyder-Mackler

Subproject 4 was designed to determine the effect of restoring normal anatomic realignment of the tibiofemoral joint on movement and muscle activity patterns in patients with osteoarthritis (OA) in the knee.  Patients who underwent opening wedge osteotomy to correct genuvarum were tested in the Motion Analysis Laboratory (see left) to determine if their muscles are activated differently when their knee joint was realigned. Testing included conditions in which the knee was subjected to a valgus stress and level walking. We hypothesized that the reduction of the laxity and pseudolaxity associated with genuvarum would restore normal quadriceps function and result in higher muscle force production, more normal muscle stabilization strategies and more normal reflex activation. Testing took place before surgery and after surgery at various intervals. In addition to determining if the restoration of normal anatomical alignment results in normal function we also examined whether changes in walking and muscle activation were consistent with conditions that could lead to reduced progression of OA.

Ramsey DK, Snyder-Mackler L, Lewek MD, Newcomb W, Rudolph KS. Effect of Anatomical Realignment on Muscle Function During Gait in Patients with Medial Compartment Knee Osteoarthritis. Arthritis Rheum 2007 57(3):389-397. Briem K, Ramsey DK, Rudolph KS, Newcomb W, Snyder-Mackler L. Effects of the amount of valgus correction for medial compartment knee osteoarthritis. J Orthop Res. 2007 Mar;25(3):311-8. Lewek MD, Scholz J, Rudolph KS, Snyder-Mackler L. Stride-to-stride variability of knee motion in patients with knee osteoarthritis. Gait Posture. 2006 Jun;23(4):505-11. Lewek MD, Ramsey D, Snyder-Mackler L Rudolph KS. Knee stabilization in patients with medial compartment knee osteoarthritis. Arthritis Rheum. 2005 Sep;52(9):2845-53. Lewek M, Rudolph KS, Snyder-Mackler L, Control of Frontal Plane Knee Laxity during Gait in Patients with Medial Compartment Knee Osteoarthritis.  Osteoarthritis and Cartilage.  2004 Sep;12(9):745-51. Lewek, M., Rudolph, K.S., Snyder-Mackler, L.  Quadriceps Femoris Muscle Weakness and Activation Failure in Patients With Symptomatic Knee Osteoarthritis.  Journal of Orthopaedic Research.  2004 Jan;22(1):110-5.

Biomedical Research Partnership  (top)

FES and Biomechanics Treating Movement Disorders NIH 1R01HD038582 (PI: Buchanan) 7aug02 - 31jul07 Role: Investigator,  Collaborators:  John Scholz, Stuart Binder-Macleod. Sunil Agrawal, Abbas Fattah, Kurt Manal This Biomedical Research Partnership project combines resources from the departments of Mechanical Engineering and Physical Therapy through our newly organized Center for Biomedical Engineering Research at the University of Delaware.  The five-year goal of this project is to assist patients with CNS dysfunction to produce improved walking patterns through a combination of functional electrical stimulation (FES), robotic-assistive training and biomechanical modeling.

1. Banala SK, Agrawal SK, Fattah A, Rudolph K, Scholz J.  A Gravity Balancing Leg Orthosis for Robotic Rehabilitation. IEEE Transactions on Neural Systems & Rehabilitation Engineering  IEEE Proceedings on International Conference of Robotics and Automation, 2004, 2474-2479.

INNOVATIVE REHABILITATION INterventions (top)

Smart Fluids for Physical Rehabilitation (PI: Rudolph)
NIH R21-HD40956-01 (17sep01 - 30jun04)
Collaborators: 
Jian-Qiao Sun PhD, Stuart Binder-MacLeod PT, PhD, Lynn Snyder-Mackler PT, PhD

Smart Fluid is one that contains magnetic particles that align in response to an applied magnetic field (from an electromagnet powered by a battery) to change its viscosity or resistance. The amount of resistance can be varied simply by turning a dial and can be adjusted manually by microprocessor to provide unique, patient specific resistance profiles. The goal of this three-year project is to develop and test a programmable, Smart Fluid, variable resistance exercise device (VRED) that can be used in rehabilitation of the knee (see prototype below). Future plans will include the development of VREDs that are capable of strengthening other joints.

Current Prototype

User Inputs

Visual Feedback

1. Dong S, Lu, K-Q, Sun J-Q, Rudolph K. Smart Rehabilitation Devices - Part 2. Adaptive Motion Control. Journal of Intelligent Material Systems and Structures 2006;17(7):555-561.
2. Dong S, Lu, K-Q, Sun J-Q, Rudolph K. Smart Rehabilitation Devices - Part 1. Force Tracking Control. Journal of Intelligent Material Systems and Structures 2006:Jun;17:543-552.
3. Dong S, Lu KQ, Sun JQ, Rudolph K. A prototype rehabilitation device with variable resistance and joint motion control. Med Eng Phys. 2006 May;28(4):348-55.
4. Dong S, Lu, K-Q, Sun J-Q, Rudolph K. Adaptive force regulation of muscle strengthening rehabilitation device with magnetorheological fluids. IEEE Trans Neural Syst Rehabil Eng. 2006 Mar;14(1):55-63.
5. Dong S, Lu K-Q, Sun JQ, Rudolph KS.  Rehabilitation Device with Variable Resistance and Intelligent Control.  Medical Engineering & Physics 2005;27:249-255.

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