|
Introduction: OA is by far
the most common form of arthritis in the United States,
affecting up to 15% of the general population. If x-ray
studies are performed on all individuals over the age of 80,
the majority exhibit evidence for OA, whether or not the
changes seen are causing pain, stiffness, or other symptoms.
For this reason, OA is the major reason behind joint
replacement surgery in this country. Women have a higher
prevalence of OA than men for every joint but the hip, where
men tend to predominate.
Features of OA: The strong
association of OA with advanced age has led many people to
believe that OA is simply �old age,� but it is much more than
this. It is a disease affecting the cartilage, the layer of
cushioning between the joints that normally allows the bony
surfaces to glide smoothly. When the cartilage becomes worn
down, joint movement is restricted and often painful or
accompanied by a �crunching� sensation we call crepitus.
This is a result of the smooth surface of the cartilage being
worn away. Aging, obesity, injury, repetitive overuse, and
coexisting inflammatory diseases such as rheumatoid arthritis
(RA) all predispose an individual to developing OA of a given
joint.
Joints most
commonly affected by OA are weight-bearing joints such as the
knees, hips, neck, and lumbar spine (lower back). In the
hands, the two rows of knuckles at the end of the fingers and
the joint at the base of the thumb are commonly involved, as
are the balls of the feet and tips of the toes. The wrists,
elbows, and ankles tend to be spared unless another
inflammatory disease or injury is also present.
While many
patients with OA may have symptoms in many joints, it is more
common to see only a few joints at a time to become
symptomatic. The onset of pain is usually gradual but may be
accompanied by brief morning stiffness as well as swelling or
local warmth over an involved joint. Nonetheless, the
intensity of the inflammation is generally less than what is
observed in RA or gout. Bony enlargement often occurs around
affected joints, which is viewed as a reaction of the
underlying bone to joint damage.
A special form
of OA isolated to the hands and occurring more commonly in
women in their 40�s or 50�s is referred to as erosive
or inflammatory OA. This condition tends to be
hereditary and is accompanied by more prominent signs of
inflammation over the finger joints, such as redness,
swelling, or warmth. Typically, the active inflammatory phase
of erosive OA lasts up to 10 years, after which time the
disease �burns out� and usually leaves behind areas of bony
enlargement near the fingertips known as
Heberden�s nodes.
Diagnosis: OA is often suspected when the pattern
of symptoms, the joints involved, and the physical examination
findings are consistent with this diagnosis. For example, a
chronically painful knee with crepitus and restricted range of
motion in patient over the age of 65 or findings of bony
enlargement over the fingers would strongly suggest OA.
X-ray studies can confirm the diagnosis as well as helping to
exclude other conditions that may be present along with OA
(see section on Calcium Pyrophosphate Disease/Pseudogout,
e.g.). The typical finding is joint space narrowing. It
cannot be assumed from this finding alone, however, that the
joint space narrowing is the cause of the symptoms. Moreover,
x-rays are useful in assessing the severity or progression of
joint damage and may assist the doctor in determining whether
joint replacement surgery is an appropriate option.
There are no
laboratory tests that help to confirm the diagnosis of OA.
Most forms of OA are associated with negative tests for many
of the standard �autoimmune� diseases and normal markers of
inflammation. One exception may be erosive OA, where the
inflammatory markers may be somewhat elevated. Aspirating
fluid from a swollen joint may be necessary in certain
situations and can help distinguish OA from a more
inflammatory condition by measuring the number of white blood
cells present in the joint fluid. The white blood cell count
should be much lower in OA than in RA or gout, for example.
Treatment: While OA is very common, we
unfortunately lack specific therapies that have been proven to
address the basic problem in this condition: loss of
cartilage. For this reason, treatment is focused on reducing
symptoms and minimizing other factors, such as obesity, that
may lead to worsening of joint damage. Depending on the
complexity of each case, OA may be appropriately managed by
primary care physicians without the aid of a rheumatologist.
Exercises
focusing on improving muscle tone around affected joints are
quite useful. Studies indicate that poor muscle tone in the
thigh muscles increases the risk of progressive OA of the
knees, and similar measures to improve tone around symptomatic
joints is also appropriate. These exercises should be
symptom-limited, that is, performed as long as the
activity does not result in prolonged pain after finishing. A
physical therapist may be helpful in supervising an exercise
program consisting of muscle strengthening, stretching, and
enhancing range of motion. Also, the therapist may be helpful
in instructing a patient on the use of assistive devices such
as a cane, walker, or splint.
Medications
used to treat OA include simple analgesics such as
acetaminophen (Tylenol) for mild symptoms, and non-steroidal
anti-inflammatory drugs (NSAIDs) for more prominent symptoms (see
Medications section). Depending on other factors, your
doctor may determine that you are better suited to receive one
of the new NSAIDs that are called �COX-2 selective� drugs.
Among these medications are celecoxib (Celebrex) and
valdecoxib (Bextra). These drugs reduce the incidence of
ulcer formation or bleeding in the gut. While all of these
medications typically reduce symptoms of OA, however, they do
not delay the progression of damage to the joint.
The use of
over-the-counter glucosamine and chondroitin sulfate
preparations has grown popular in recent years. These
preparations are made of components of normal cartilage and
appear to reduce symptoms in patients with OA after 1-2 months
of use, although studies are inconsistent. A bolder claim is
that these agents reduce damage to the joint or actually
�build cartilage,� neither of which has been clearly
documented. At present, these agents may be useful and are
worth trying in certain patients, but would not be expected to
offer benefit in any other condition besides OA.
Injections
containing steroid preparations with or without anesthetic may
be performed in certain joints, such as the knee, and may be
quite helpful in reducing symptoms in an involved joint. The
steroid itself is not given in sufficient amounts to result in
side effects in the rest of the body, and the risk of the
injection itself mostly consists of a 1 in 20,000 chance if
infection being introduced into the joint by the needle.
Conventional wisdom used to dictate that there was a limit to
the number of injections that could be given, but recent
studies indicate that if they are given in intervals of no
more than every 3 months, steroid injections do not result in
further damage to the joint.
Other
substances that may be injected into the joint include
preparations containing hyaluronic acid or a derivative
known as hylan. This is a component of normal joint
fluid that becomes depleted in OA, and when injected into an
involved joint, these substances provide lubrication and
possibly coat the damaged cartilage. Currently available
preparations include Synvisc, Hyalgan, Supartz, and Orthovisc,
all of which may be given in a series of 3 to 5 weekly
injections. At present, all of these medications are
FDA-approved only for injection into the knee. On the
average, approximately 2/3 of patients undergoing these
injections experience relief of symptoms for up to 6 months at
a time. Most of these preparations are most appropriately
used in patients who have failed to respond to more
conservative treatments or who are not good candidates for
surgery.
Surgery
may be viewed as the only truly definitive therapy for OA.
The key issue in determining whether surgery is the right
option depends on many factors, including, age, health status,
which joint is involved, lack of success of other therapies,
the degree of joint space narrowing, and most importantly, the
degree of pain and limitation in function the patient is
experiencing. A dialogue between you and your doctor is of
utmost importance when making this decision.
The choice of a skilled and experienced surgeon is crucial,
but up to 90% of patients undergoing hip or knee replacement
surgery report either good or excellent results. Surgery
involving the spine or other joints is met with lower success
rates, but if patients are carefully selected for such
procedures, they too may experience significant relief of pain
and recovery of function. While the short-term risk and
rehabilitation process afterward are considerations, the
long-term investment is usually worthwhile. |
