Osteoarthritis (OA), is the most common form of arthritis, mainly caused by age, genetic predisposition, obesity and prior joint injuries. OA affects all weight bearing joints, especially the knee. It is characterized by inflammation and break down of the shock absorbing articular cartilage within the joint. Thus, the bones grind together and the symptoms such as pain, swelling, inflammation, bone spur formation and impaired mobility result.

To date, no effective or curative treatment is available for OA. Current therapies are primarily targeted at reducing pain and inflammation. Hyaluronic acid is used to restore the visco-elasticity to the joint fluid to reduce joint pain and increase mobility. With the lack of treatment options, the replacement of the affected joint becomes ultimately inevitable. It is estimated that more than 90% of all artificial joint replacements are caused by defective cartilage.

CD-RAP is a polypeptide that has been shown to play a crucial role during cartilage formation during embryonic development and in the matrix stimulation of chondrocytes in adult animals. Furthermore it has been shown to stimulate cartilage synthesis in in-vitro studies with chondrocytes obtained from patients suffering from osteoarthritis. These properties make rhCD-RAP a highly promising candidate for osteoarthritis.