The objective of our research program is to discover new information relating to the diagnosis, treatment and repair of damaged joints as a consequence of disease or mechanical injury. To carry out this objective, studies which improve our understanding of how the musculoskeletal system functions normally and how it responds to disease and trauma are being conducted in our laboratory. Furthermore, experiments are also being performed to provide the scientific basis for current and future treatment modalities. Three major areas of investigation are being pursued:

1) Cartilage and Bone Repair by Tissue Engineering

• Degenerative joint diseases such as osteoarthritis and osteonecrosis result in extreme pain and loss of function. If the disease is permitted to progress unimpeded, ultimately joint replacement becomes necessary. A revolutionary approach to cartilage and bone repair is being developed and characterized in our laboratories. Cells removed from our body can be grown in a three dimensional culture system. These cells can then be Aseeded onto a matrix (or scaffold) to create a mechanically stable biomaterial which can then be used to replace the damaged tissue in the diseased joint. We are evaluating a number of different cell types, biological agents, and drugs which can be used to enhance the characteristics of this system.

2) Evaluation and Improvement of Total Hip and Total Knee Prostheses

• Our faculty and research laboratories have been actively involved in the research and development of total hip and total knee prostheses for over twenty years. Data from our studies have led to improvements in both prosthesis designs and surgical technique. One major goal of our current projects is to identify those factors which may improve the overall clinical success of total joint surgery. We are also investigating what occurs when joint replacement Afails@. Studies are being conducted to examine the biological effect of prosthetic wear debris and their degradation products on inflammatory and immune cells. The principle aim of one of our on-going projects is to investigate the possible interrelationship between wear debris and prosthetic instability.

3) Pathogenesis and Treatment of Osteonecrosis

• Osteonecrosis was first described by Phemister in 1915. Yet 94 years later, we still do not know what causes idiopathic osteonecrosis. Our laboratory has been committed to the study of osteonecrosis since its beginning in 1976. Originally funded by a three-year NIH grant, we studied the effect of steroids on blood flow in a number of animal models. We continue to examine different factors which may contribute to this disease. We have also been involved in the evaluation of improved MRI techniques for early diagnosis of osteonecrosis. Currently, we are evaluating: 1) the epidemiology of osteonecrosis, 2) the role of corticosteroids in the development of osteonecrosis, and 3) the cellular events that occur during the different stages of osteonecrosis.