Osteoarthritis is the most common form of arthritis. It is the type of arthritis that people think about when they talk about arthritis and aging.
More than 90 percent of people over the age of 50 will eventually develop some type of arthritis and that type is usually osteoarthritis (OA). OA preferentially attacks the weight bearing areas of the skeleton including the neck, low back, hips, knees, base of the big toe, and base of the thumb.
OA develops because of the loss of cartilage, the gristle that caps the ends of long bones within a joint. Cartilage consists of a matrix consisting of glycosaminoglycans. Within this matrix are cells called chondrocytes that help make new cartilage.
OA develops when there is an imbalance between the normal synthesis and the normal breakdown of cartilage. Certain components within the glycosaminoglycan matrix are lost, water accumulates, and enzymes such as matrix metallo-proteinases begin to “chew away” at cartilage. The end result is cracking and wearing away of cartilage.
The diagnosis of OA is established through a careful history and physical examination. Standard x-rays and sometimes ultrasound or magnetic resonance imaging can better quantify the degree of damage the arthritis has caused.
Treatment of this order involves modalities requiring medication and those that don’t. Non drug therapies consist of patient education, exercise, physical and occupational therapy, assistive devices such as canes, walkers, thermal modalities (heat or ice), and weight loss, if indicated.
Medications used to treat OA include analgesics, non-steroidal-anti-inflammatory drugs, topical analgesics, and joint injections with either glucocorticoid (steroid) or hyaluronan (lubricants).
Some work has been done to try and develop drugs that block the effects of matrix-metalloproteinase inhibitors.
Surgical procedures such as arthroscopic debridement and total joint replacement also have a role in treatment.
More recently, devices such as polymer spacers have been used in some joints.
A current type of treatment for younger osteoarthritis patients is to harvest cartilage cells from nearby healthy cartilage and transplant them into the affected area. This procedure has limitations because only a limited number of cells can be generated.
A more exciting development is the role of stem cells.
Scientists at Britain’s Cardiff University have identified a type of stem cell that can be transformed into cartilage cells (chondrocytes).
If this research pans out, it should be possible to create enough new chondrocytes to have a real therapeutic effect in osteoarthritis patients. Immature stem cells have the ability to become any tissue in the body. What’s interesting about the British study is that the cells they have discovered are at a more advanced stage. While they no longer have the ability to differentiate into any cell, they do have the ability to become a chondrocyte when properly cultured in the lab.
In essence, by culturing these cells, scientists will be able to grow a substantial number of cartilage cells that can be transplanted.
In addition to the stem cells, addition of growth factors from substances like platelet rich plasma (PRP) may hasten the growth of cartilage.
The Cardiff team is now conducting tests in animals, with the hope of initiating a clinical trial in the near future.
About the author of this article:
nathan wei, md facp facr is a rheumatologist and director of the arthritis and osteoporosis center of maryland. he is a clinical assistant professor of medicine at the university of maryland school of medicine. for more info: arthritis treatment