Osteoarthritis (OA), or degenerative joint disease, is a condition that affects an estimated 21 million people in the United States alone. It is characterized by mild to debilitating joint pain and is most prevalent among individuals 45 years of age or older.

Patients with osteoarthritis of the knee will often present with pain, swelling, tenderness, or stiffness at the affected knee joint. The pain is usually activity related made worse during weight-bearing activities and improved with rest.

Osteoarthritis of the knee is classified as either primary (idiopathic) OA or secondary OA stemming from prior joint injury. The progressive disease process involves the gradual deterioration of the protective cartilage covered joint surfaces, which gradually leads to painful bone on bone contact. It is the leading cause of disability worldwide and one of the top 10 most expensive medical conditions in the United States.

As the "baby-boomer" population continues to age and lead more active lifestyles, osteoarthritis treatments have become the focal point of many orthopedic, pharmaceutical, and biotech companies.