Arthritis Of The Foot
Dr. Jeffrey A. Oster, Medical Director Of Myfootshop.com.
Arthritis is a term used to describe a number of diseases that cause inflammation of joints and results in the progressive destruction of joints. Arthritis is actually a collection of many different joint diseases that affect the body and the foot in many different ways. In this article, let’s talk a bit about arthritis and how it affects the foot. We normally discuss treatment alternative for conditions, but due to the scope of this topic, we will not discuss treatment of each of the individual forms of arthritis.
Osteoarthritis
Osteoarthritis is by far and away the most common form of arthritis. Osteoarthritis is known as the wear and tear type of joint disease and will effect most of us at one point in our lives. In our discussion on osteoarthritis, please refer to the nomenclature and anatomy sections below for definitions of the terms that my be unfamiliar to you.
When I think of osteoarthritis (OA), I think of my grandmother’s hands. Those hand have done a lot of work in their time and have a bit of arthritis to show for it. The fingers, crooked and bumpy show many of the changes brought on by osteoarthritis. The bumps on the fingers are called Heberden’s Nodes. Heberden’s Nodes are a very obvious example of how osteoarthritis occurs. If you’ve ever known anyone whose experienced the symptoms of OA, they’ll tell you that a joint will flare for a period of several weeks. It may be mildly painful or even painful to the degree that the joint is unusable. And then suddenly, just as passively as it came, it leaves. Occasional, brief morning stiffness was not unusual for grandma. The pain that had been present in her hands was actually due to a series of small micro-fractures that occurred in the subchondral bone (just beneath the cartilage). It seems that in cases of osteoarthritis, the bone just below the cartilage becomes very fragile. When loads are applied to this fragile bone, it breaks down. The more the joint is used, the more the bone seems to break down.
Over time, as the bone undergoes a series of flare ups, the ability of the bone to support the cartilage becomes unstable. The subchondral bone creates an unstable supporting surface for the cartilage. When the joint tries to complete its’ normal range of motion, the cartilage is irregular and progressively erodes. This moves us into the second phase of OA pain, and that’s when we have joint range of motion that is bone on bone. Cartilage has no nerve endings to sense pain, but bone on the other hand, has plenty. As the joint moves and the bone is eroded, significant pain can be experienced.
This erosive process seen in OA seems to occur at different rates in everyone. In fact, every joint seems to undergo the changes of OA at a different rate. The rate of change does seem to be effected by the history of damage to the joint. In fact the classifications used to describe OA include Primary (idiopathic or no known cause) and Secondary (some known cause for the disease such as trauma). Past injuries seem to accelerate the rate of OA in most joints. We all know someone with that old football injury, right?
The cause of OA is unknown. Many authors have speculated that the cause may be mechanical as described above, but others have described changes such as biologic, biochemical or enzymatic; or even a combination of each of these.
Changes that occur in the foot with OA are numerous. The most common is midfoot pain that is diffuse. The midfoot is a jigsaw puzzle of pieces that are difficult to manage when effected by a systemic disease of this nature. Other finding include atrophy (loss) of the plantar fat pad of the forefoot and heel. The big toe joint is often effected by the changes of OA with bunions and hallux limitus as common complaints.
Rheumatoid Arthritis
Rheumatoid arthritis (RA) is a very complex and debilitating disease that affects approximately 1% of the general population. Women are 2-3 times more prone to develop RA. RA is a process where the body’s immune system attacks the cell lining the joint capsule (synovial cells). The end result is thickening and fibrosis of the joint with destruction of the cartilage.
Symptoms of RA include an abrupt onset of inflammation. The swelling associated with RA may be isolated to one joint or effect several. Symmetrical involvement is typical with both hands or both feet being affected. In comparison to OA, morning stiffness seen in RA may last more than 30 minutes.
The finding of RA in the foot often progresses to subluxation of the joints, particularly the metatarsal phalangeal joints. Atrophy of the plantar fat pad is common.
Psoriatic Arthritis
Psoriatic arthritis (PA) is an interesting form of sero-negative arthritis. PA is associated with psoriasis in many cases, but it is not unusual to find the symptoms of PA in a patient with no previous history of psoriasis of the skin or nail.
The symptoms of PA in the foot include focal swelling of the interphalangeal joint (the toes). The toe will appear to have swollen and become painful with a limited history of injury or pain. X-rays often show slow changes that exhibit erosion called a pencil and cup appearance. This finding is common on the metatarsal phalangeal joint.
Reiter’s Syndrome
Reiter’s Syndrome (RS) is an unusual form of arthritis that is usually found in men.. RS is often described as a sexually transmitted disease due to the history of the disease occurring following sexual intercourse which resulted in a chlamydial infection. It is suggested to treat those with RS, and their sexual partners, for C. trachomatis infections.
The symptoms of RS include burning upon urination (urethritis), dry eyes and joint pain. Joint pain in the back and feet are common. These symptoms occur 7-14 days following sexual intercourse and subside over a period of several months to years. Recurrence of pain is not unusual. About the Author
Jeffrey A. Oster, DPM, C.Ped is a board certified foot and ankle surgeon. Dr. Oster is also board certified in pedorthics. Dr. Oster is medical director of Myfootshop.com and is in active practice in Granville, Ohio.