By far the most common joint disease - especially in later
life -
osteoarthritis (OA) occurs when the cartilage that lines and cushions
joints breaks down and the bones rub painfully against each other. It
tends to affect the small joints of the fingers, the large
weight-bearing joints of the hips and knees, or the vertebrae in the
upper spine, a condition known as cervical spondylosis.
Cartilage cushions many joints; it is very smooth, allowing the bone
ends that form a joint to glide easily over each other. In
osteoarthritis, the cartilage lining the affected joints becomes
roughened and patches of it are destroyed. The underlying bone thickens
in an attempt to repair the joint. Spurs of bone known as osteophytes
form around the joint, causing swelling.
Often the joints repair themselves adequately with time and the pain
may then settle. However, in some cases the damage is not successfully
repaired, the pain becomes more persistent and the joint no longer
works properly. Eventually, the joint may become deformed. The muscles
around the joint also weaken, which may in turn affect the joint's
stability.
In some cases, calcium crystals form within the cartilage of a joint
affected by OA - the knee is particularly susceptible to this. The OA
in such joints tends to be more severe and to worsen more quickly. In
addition, periods of inflammation may occur causing increased pain and
swelling of the joint. During these times, the joint may also feel hot
to the touch. These flare-ups are similar to those that occur in gout,
a condition caused by the deposition of urate crystals within joints.
The condition is therefore known as pseudogout.
What are the causes?
It is not completely understood how osteoarthritis develops and often
no particular reason can be identified. Various factors that may play a
role include:
Aging - we are more likely to develop
osteoarthritis as we
get older; the condition usually begins to develop after the age of 40.
OA is not an inevitable consequence of getting older but aging does
increase the effects of general wear and tear on joints.
Genetic Factors - these are thought to
play a role,
although specific genes responsible have not yet been identified. Nodal
arthritis tends to run in families.
Gender - for most joints, particularly
the small joints in
the hand, OA is more common in women.
Sex hormones - as the disease is more
common in women after
the menopause, falling levels of oestrogen may play a part.
Obesity - this is a major risk factor
for
developing OA later in life, particularly increasing the risk
of OA of the knee.
Injuries - serious damage or trauma to a
joint, such as a
fracture, can also increase the risk of OA, although the disease may
not develop until many years later. Operations on joints can also make
them vulnerable to OA.
Certain sports - sports that inflict
stress repeatedly on a
joint can lead to OA. For example, football or rugby, if played
frequently over long periods, can increase the risk of the condition
developing in players as young as in their 30s.
Joint problems - certain joint problems
that are present
from birth can result in OA later in life.
Certain joint diseases - joint diseases
that involve
inflammation, such as rheumatoid arthritis and gout can predispose to
OA.
Certain occupations - jobs that put
joints under particular
strain can lead to the condition. For example, farming is associated
with OA of the hip.
What are the symptoms?
Symptoms tend to come on gradually with the severity varying from day
to day:
Pain and tenderness
Stiffness
Restricted movement
A creaking sensation as the joint moves
Swelling of the joint - due to fluid collected within the
joint capsule.
Bony swellings (osteophytes) on the joint after rest but
improve with movement.
