Research Projects: Biomechanics and Musculoskeletal Imaging Lab

Meniscus KinematicsKnee Osteoarthritis: Meniscus Kinematics and Articular Cartilage Degeneration

Osteoarthritis (OA) onset and progression is thought to be related to altered mechanical loading during daily activities. A fibrocartilagenous structure within the knee called the meniscus serves to distribute load across the joint to protect the underlying articular cartilage and bone. The meniscus is known to move as the knee flexes and extends, however abnormal meniscal movement during tasks such as walking and other activities of daily living may play an important role in the onset and progression of knee OA. Advanced quantitative magnetic resonance imaging (MRI) techniques may be used to evaluate meniscal motion, cartilage compositional changes, joint contact mechanics, and radiological grading of disease severity.

Therefore, the purpose of this project is to perform both cross-sectional (OA vs. controls) and longitudinal (3 times over two years) studies of meniscal motion in relationship to cartilage biochemistry. One hundred subjects with and without knee OA have been enrolled to complete kinematic-MRI and relaxation time mapping for cartilage and meniscus composition. Characterizing meniscal kinematics in participants with knee OA will improve out understanding of the mechanisms behind the incidence and progression of knee OA. This knowledge may be directly translated to the clinical setting since altered meniscal movement and morphology may be treated through surgical intervention, and targeting treatment specifically to those individuals that have the greatest risk for cartilage degeneration.

This research is supported by the National Institute of Arthritis and Musculoskeletal and Skin Diseases of the National Institutes of Health under Award Number 1R01AR062370 (PI: Souza) and 1F32AR064129 (PI: MacLeod). The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.

Knee OsteoarthritisMuscle Adiposity, Function, and Performance in Knee Osteoarthritis

It is well known that obesity has a strong association with the risk of development and worsening of knee osteoarthritis. Weakness of the thigh muscles, especially the Quadriceps is a ubiquitous finding in people with knee OA. Loss of muscle tissue only partly explains the loss of strength in people with OA and fatty infiltration of thigh skeletal muscle is known to affect muscle strength and mobility in the elderly. However, little attention has been paid to the changes in fatty- infiltration of the thigh muscles in people with knee osteoarthritis. Using cutting-edge chemical shift-based water/fat separation MRI methods, including Dixon techniques and the iterative decomposition of water and fat with echo asymmetry and least-squares estimation (IDEAL), we are investigating the changes in thigh muscle size and adiposity in people with knee osteoarthritis. Furthermore, we are also investigating the association of thigh muscle size and adiposity with cartilage degeneration, muscle performance, and patient symptoms, function, and biomechanics.  The project is currently funded by two grants from NIH-NIAMS (PI: Dr. Richard Souza, PI: Dr. Sharmila Majumdar).

meniscectomyChanges in Tibiofemoral Kinematics and Articular Cartilage Before and After Meniscectomy

The medial and lateral meniscus are crescent-shaped fibrous pads of the knee joint that provide shock absorption, pressure redistribution, and joint stability contributing to the smooth motion of the knee. However, meniscus tears are among the most common injuries seen by orthopaedic surgeons, and meniscectomy is the most common orthopaedic procedure performed in the United States.

While studies have shown that meniscus tears and partial meniscectomy result in histological changes in articular cartilage and altered tibiofemoral kinematics, it is still unclear if the cartilage changes seen following surgery are a result of the original meniscus tear itself, the partial meniscectomy, or other factors.

This study utilizes state-of-the-art MR techniques to monitor knee cartilage composition with changes in load across the knee joint. Patients who electively undergo meniscectomy will be evaluated before the meniscus surgery and after the surgery to see the effects on the load of the knee.

The results of this study are necessary to determine how changes in mechanical load across the knee results in biochemical changes in the cartilage. Outcomes from our study could potentially allow clinicians to see sub-clinical early osteoarthritis following meniscus injury and provide a way to measure therapeutic interventions before it is irreversible

Foot progression angleGait Retraining to Reduce Knee Pain and Improve Function in Osteoarthritic Patient

The angle of an individual’s feet while walking may place exaggerated stress on certain portions of the knee joint, particularly the medial compartment. This exaggerated load leads to altered movement and cartilage degeneration of the knee which may eventually lead to osteoarthritis. The Gait Retraining Pilot is an interventional study that aims to change the way participants walk in order to reduce loading on the medial compartment of the knee joint. The knee adduction moment (KAM) is a biomechanical variable used to measure this amount of loading on the joint, and is linked to the severity of knee pain in people with Osteoarthritis. The cartilage degeneration resulting from high KAM’s can be visualized using T1ρ and T2 relaxation times from MRI.

In a recent study, it was found that a subtle 7 degree change in the foot progression angle (amount of toe-in) can reduce the KAM during walking by 20%, and show a dramatic improvement in both pain and function in persons with moderate knee OA. However, it remains unknown if this intervention may result in improvements (or less decline) in cartilage composition, as quantified by T1ρ and T2 relaxation times. In addition, the effects of gait retraining on the kinematics and kinetics during similar, but different tasks (such as stair climbing), has not been explored.

Therefore, the objective of this study is to determine the effects of 2, six week long, gait retraining interventions (a moderate 7 degree toe-in modification, and a mild 2 degree toe-in modification) on cartilage composition, muscle and joint morphology, pain, function, and kinematics and kinetics during functional tasks in persons with symptomatic and radiographic knee OA.

2-D Running Analysis Write-up

When measured from multiple angles, 2-dimesional video can give great insight into running mechanics, allowing for a frame-by-frame biomechanical analysis. Variables which dictate running patterns (such as overstride, thigh extension, footstrike, and heel whip) can be reliably measured and quantified. Once gathered, the correlation between these components can be calculated and used to make predictions about the effect of each.

Peak Thigh Extension

Peak thigh extension

Peak Ankle Eversion

Peak ankle eversion

Overstride Angle

Overstride angle

Overstride Distance (Normal)

Overstride distance (normal)

Overstride Distance (Excessive)

Overstride distance (excessive)