Osteoarthritis
(Degenerative
Arthritis)
Medical Author:
William C. Shiel Jr., MD, FACP, FACR
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Early, Mild Osteoarthritis of the Hands
What to Do if It Affects You!
Medical Author: William C. Shiel, Jr., MD,
FACP, FACR
Medical Editor: Leslie J. Schoenfield, MD, PhD
 Osteoarthritis is a type of arthritis that is caused by breakdown of
cartilage, with eventual loss of the cartilage of the joints. Cartilage is a
protein substance that serves as a "cushion" between the bones of the
joints. When the cartilage deteriorates (degenerates), the bone next to it
becomes inflamed and can be stimulated to produce new bone in the form of a
local bony protrusion, called a "spur."
A very common early sign of osteoarthritis is a knobby bony deformity at the
smallest joint of the end of the fingers. This is referred to as a Heberden's
node, named after a very famous British doctor. The bony deformity is a result
of the bone spurs from the osteoarthritis in that joint. Another common bony
knob (node) occurs at the middle joint of the fingers in many patients with
osteoarthritis and is called a Bouchard's node.
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What is osteoarthritis?
Osteoarthritis is a type of arthritis that is caused by the
breakdown and eventual loss of the cartilage of one or
more joints. Cartilage is a protein substance that serves as a "cushion" between
the bones of the joints. Osteoarthritis is also known as degenerative arthritis.
Among the over 100 different types of arthritis conditions, osteoarthritis is
the most common, affecting over 20 million people in the United States.
Osteoarthritis occurs more frequently as we age. Before age 45, osteoarthritis
occurs more frequently in males. After age 55 years, it occurs more frequently
in females. In the United States, all races appear equally affected. A higher
incidence of
osteoarthritis exists
in the Japanese population, while South African blacks, East
Indians and
Southern Chinese have lower rates.
Osteoarthritis commonly affects the hands, feet, spine, and large
weight-bearing joints, such as the hips and knees. Most cases of osteoarthritis
have no known cause and are referred to as primary osteoarthritis. When the
cause of the osteoarthritis is known, the condition is
referred to as
secondary osteoarthritis.
What causes osteoarthritis?
Primary osteoarthritis is mostly related to aging. With aging, the
water content of the cartilage increases and the protein makeup of cartilage
degenerates. Repetitive use of the joints over the years irritates and inflames
the cartilage, causing joint pain and swelling.
Eventually,
cartilage begins to degenerate by flaking or forming tiny
crevasses. In
advanced cases, there is a total loss of the cartilage cushion
between the
bones of the joints. Loss of cartilage cushion causes friction
between the
bones, leading to pain and limitation of joint mobility.
Inflammation of the
cartilage can also stimulate new bone outgrowths (spurs) to form around the
joints. Osteoarthritis occasionally can be found in multiple members of the same
family, implying an heredity (genetic)
basis for this
condition.
Secondary osteoarthritis is caused by another disease or
condition.
Conditions that can lead to secondary osteoarthritis include
obesity,
repeated trauma or surgery to the joint
structures, abnormal joints at birth (congenital abnormalities), gout, diabetes and other
hormone
disorders.
Obesity causes osteoarthritis by increasing the mechanical
stress on the
cartilage. In fact, next to aging, obesity is the most powerful risk factor for osteoarthritis of the knees. The early development of osteoarthritis of the knees
among
weight lifters is believed to be in part due to their high body
weight.
Repeated trauma to joint tissues (ligaments, bones and
cartilage) is
believed to lead to early osteoarthritis of the knees in soccer
players.
Interestingly, recent studies have not found an increased risk
of
osteoarthritis in long-distance runners.
Crystal deposits in the cartilage can cause cartilage
degeneration, and
osteoarthritis. Uric acid crystals cause arthritis in gout, while calcium
pyrophosphate crystals cause arthritis in pseudogout.
Some people are born with abnormally formed joints (congenital
abnormalities) that are vulnerable to mechanical wear, causing
early
degeneration and loss of joint cartilage. Osteoarthritis of the
hip joints
is commonly related to design abnormalities of these
joints that had been present since birth.
Hormone disturbances, such as diabetes and growth hormone
disorders, are
also associated with early cartilage wear and secondary
osteoarthritis.
Next: What are symptoms of osteoarthritis? »
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