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WHAT
CAUSES OSTEO-ARTHRITIS?
The real roots of osteo-arthritis, and how you can effectively
treat osteo-arthritis
Although
osteo-arthritis generally accompanies aging, osteo-arthritic cartilage
is chemically different from normal aged cartilage. Many experts
now believe that osteo-arthritis is a disorder that results from
a genetic susceptibility coupled with injuries to the joint.
Genetic and Biologic Factors & Osteo-arthritis
Researchers report a higher correlation of osteo-arthritis between
parents and children or between siblings than between husbands
and wives. Genetic factors are thought to be involved in about
half of osteo-arthritis cases in the hands and hips and a somewhat
lower percentage of cases in the knee. A number of genes are under
investigation that might contribute to an inherited risk.
A 2000 study identified the ank gene, which regulates pyrophosphate,
a chemical that inhibits the formation of mineral deposits, and
may protect the cartilage in joints. (Pyrophospate is also a substance
used in tartar control toothpaste). About 60% of persons with
osteo-arthritis have mineral deposits in their cartilage. Researchers
in the study suggested that mutations in the ank gene that may
result in lower pyrophosphate levels in the joint, leading to
accumulation of mineral deposits and arthritis.
The
newly detected osteo-protegerin gene is important in regulating
bone and cartilage formation. Mutations in this gene may play
a in role in osteo-arthritis.
Muscle Weakness
It is commonly thought that osteo-arthritis results in disuse
in the muscles of the leg, causing them to weaken and atrophy.
Of interest is a study that reverses this thinking. It suggested
that weak muscle tissue in the quadriceps is responsible for osteo-arthritis
in the first place. (The quadriceps are four muscles that stretch
down the thigh and attach to the knee and are responsible for
leg extension.) This weakness may be due to an abnormality in
the muscles themselves or in the nerves that serve those muscles.
In the study, strength tests revealed that people with osteo-arthritis
had muscle weakness in the quadriceps even if they had no pain.
There was no difference in signs of muscle atrophy (withering)
between the legs of osteo-arthritic patients and those of nonarthritic
people.
Anatomical
Factors & Osteo-arthritis
Some
researchers suggest that a number of people have anatomical abnormalities,
such as mismatched surfaces on the joints, which could be damaged
over time by abnormal stress. Legs of unequal length or skewed
feet can cause jerky movement and may induce osteo-arthritis.
In a study on hand grip strength, for example, individuals, particularly
men, whose grip was very powerful were at increased risk of developing
osteo-arthritis in certain hand joints over time.
Injuries & Osteo-arthritis
Injury from different sources can contribute to osteo-arthritis:
Single
Injury
Osteo-arthritis sometimes develops after a single traumatic injury
to or near a joint. This is referred to as secondary osteo-arthritis.
Repetitive
Labor & Osteo-arthritis
Certain occupations that require repeated stressful motions (such
as squatting or kneeling with heavy lifting) can also contribute
to deterioration of cartilage.
High-Intensity
Exercise & Osteo-arthritis
There has been some question about the role of strenuous exercise
in osteo-arthritis. Marathon runners, for instance, have a relatively
low rate of osteo-arthritis in general. One study that did report
a higher rate of osteo-arthritis in marathon runners compared
to other athletes associated it with intensity of impact rather
than with the distance being run. Other scientists, however, speculate
that running enhances cartilage health because the rhythmical
compression of cartilage expels wastes and promotes absorption
of nutrients. Sports that definitely pose a higher risk for osteo-arthritis
are those that require repetitive or direct joint impact (such
as football), twisting, or both (baseball, soccer). It should
be noted however, that muscle weakness and low lung capacity are
associated with a high risk for osteo-arthritis and non-traumatic
exercise is strongly recommended for healthy people.
Obesity & Osteo-arthritis
Being overweight exacerbates osteo-arthritis once deterioration
begins. One major long-term study suggested there may be a causal
relationship between obesity in women and osteo-arthritis of the
knees. In men, the association is not as strong.
WHAT
ARE THE SYMPTOMS OF OSTEOARTHRITIS?
The
pain of osteoarthritis almost always begins gradually, progressing
slowly over many years. People under 40 may have the condition
with no symptoms at all. Osteoarthritis is commonly identified
by the following symptoms:
-
Aching
pain in one or more joints, stiffness, and loss of mobility.
-
Inflammation
may or may not be present.
- Stiffness
tends to follow periods of inactivity, such as sleep or sitting,
and can be eased by stretching and exercise.
- The
pain may behave like a roller coaster, with bad spells followed
by periods of relative relief.
- Pain
seems to increase in humid weather.
- It
often worsens after extensive use of the joint and is more likely
to occur at night than in the morning. As the disease advances,
the pain may occur even when the joint is at rest and can keep
a sufferer awake at night.
- Osteoarthritis
in the knee may cause a crackling like noise (called crepitus)
when moved.
WHAT
OTHER CONDITIONS SHOW THE SAME SYMPTOMS AS OSTEOARTHRITIS?
It
would be impossible to discuss in this report all the numerous conditions
that have symptoms of joint aches and pains. Something as benign
as sleeping on a bad mattress to the serious afflictions associated
with cancer can mirror symptoms of osteoarthritis. Other problems
that can cause aches and pains in the joints include physical injuries,
infections, and poor circulation. A number of rare genetic diseases
attack the joints.
Osteoarthritis
can generally be distinguished from other joint diseases by considering
a number of factors together: osteoarthritis usually occurs in older
people and is located in only one or a few joints; the joints are
less inflamed than in other arthritic conditions, and progression
of pain is almost always gradual.
A
few of the most common disorders that can be confused with, or may
even accompany, osteoarthritis are worth noting.
Rheumatoid Arthritis
Osteoarthritis may be confused with rheumatoid arthritis, particularly
when osteoarthritis affects multiple joints in the body. Rheumatoid
arthritis begins in the synovial membrane rather than the cartilage.
It normally occurs earlier in life than osteoarthritis, often striking
people in their 30s and 40s. Many joints are affected, and rheumatoid
arthritis often occurs symmetrically on both sides of the body.
People generally have morning stiffness that lasts for at least
an hour. (Stiffness from osteoarthritis usually clears up within
half an hour.) X-rays show changes in the bones that differ from
those occurring in osteoarthritis. In rheumatoid arthritis, blood
tests often show a specific antibody, known as rheumatoid factor,
that is not present with osteoarthritis. In another blood test,
levels of a factor called erythrocyte sedimentation rate (ESR) are
often elevated in rheumatoid arthritis, but they are generally normal
in osteoarthritis. Rheumatoid arthritis also does not usually show
up in the fingertips where osteoarthritis is common.
Chondrocalcinosis
Chondrocalcinosis is a disease in which certain calcium crystals
known as CPPD (calcium pyrophosphate dihydrate) are deposited in
the joints. It may affect 25% of the population and can accompany
and even exacerbate osteoarthritis. The problem has been called
pseudogout or pseudo-osteoarthritis, in the latter case particularly
when it affects the knees. A physician can usually differentiate
between the two disorders, however, because chondrocalcinosis usually
damages other joints (such as wrists, elbows, and shoulders) that
are not normally affected by osteoarthritis.
Charcot's Joints
Charcot's joint occurs when an underlying disease, usually diabetes,
causes nerve damage in the joint, which leads to swelling, bleeding,
increased temperature, and changes in bone. There may be a loss
of sensation that leads to an increased risk for injury from overuse.
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