Osteoarthritis (OA)

Clinical Background

Arthritis is the leading cause of disability in the United States causing at least 9,500 deaths, 750,000 hospitalizations and 36 million ambulatory care visits annually within the United States. Approximately 80% of all arthritis is osteoarthritis.  The causes of arthritis are still largely unknown. Osteoarthritis (OA) is thought to be caused primarily by injury to the joint cartilage, whether through trauma or through wear and tear in old age or due to overuse.   Current treatment for OA primarily consists of non-steroidal anti-inflammatory compounds (NSAIDs).

Animal Model

Biomodels has developed a model of osteoarthritis in rats, in which the ACL and MCL of the left knee are surgically transected without damaging the meniscus.  The wound is closed and the animal is allowed to move freely.  Osteoarthritis develops over a period of 4-5 weeks and can be successfully treated with intra-articular injections of anti-inflammatories.  Systemic treatments have not yet been evaluated in this model.  End points are predominantly histological, with scores based on the OARSI modified Mankin Scale, a 17 point scale that evaluated the articular cartilage structures,  proteoglycan loss and cellularity.  Specific histological stains to evaluate articular cartilage such as Safonin O and Toluidine blue can be used, as can immunhistochemistry to evaluate the levels of specific cartilage associated proteins.  X-rays may also be taken.

OARSI Modified Mankin Score