A joint is a meeting of two bones for the purpose of allowing
movement. It has the following six parts:
Cartilage-the end of each bone is covered with cartilage,
a tough material that cushions and protects the ends
of the bone.
Synovial membrane (synovial sac)-around each joint
is the synovial sac, which protects the joint and also
secretes the synovial fluid, which oils the joint.
Bursa-a bursa is a small sac that
is not part of the joint but is near the joint. It contains
a fluid that lubricates the movement of the muscles:
muscle across muscle and muscle across bone.
Muscle-muscles are elastic tissues
that, by becoming shorter and longer, move the bones
and thus move you.
Tendon-tendons are fibrous cords that
attach the muscles to the bones.
Ligament-ligaments are much shorter
fibrous cords that attach bone to bone and make up the
joint capsules.
The knee is essentially made up of four bones. The
femur, which is the large bone in your thigh, attaches
by ligaments in a capsule to your tibia. Just below
the tibia is the fibula, which runs parallel to the
tibia. The patella (kneecap) rides on the knee joint
as the knee bends.
When the knee moves, it does not just flex and extend,
there is also a slight rotation component in this motion.
The knee muscles that cross the knee joint are the quadriceps
and the hamstrings. Quadriceps are on the front of the
knee, and hamstrings are on the back of the knee. The
ligaments are equally important in the knee joint because
they hold the joint together. Problems with ligaments
are common. In review, the bones support the knee and
provide the rigid structure of the joint, the muscles
move the joint, and the ligaments stabilize the joint.
The knee also has a structure made of cartilage, which
is called the meniscus. The cartilage protects the joint
and allows the bones to slide freely on each other.
There is also a bursa around the knee joint.
To function well, a person needs to have strong and
flexible muscles; the cartilage, ligaments, and bursa
must be smooth and strong. Problems occur when any of
these parts of the knee joint is irritated.
Meniscus Cartilage Tears
A torn meniscus usually results from a sudden twist
or repeated squatting. This usually causes your knee
to swell and hurt. You may also feel a "catching"
or locking when you bend it.
Ligament Tears
The anterior cruciate ligament may tear from a fall,
twist, or direct blow to the knee. These tears usually
cause pain, swelling and instability which can make
your knee give away.
Articular Cartilage Wear
Aging or injury may wear articular cartilage. A piece
may even break off into the joint. Pain, stiffness,
or grinding may be some of the symptoms that you would
experience.
Patella Problems
The cartilage under your kneecap can become damaged
due to aging, overuse, or a direct blow to the knee.
These structural problems can restrict joint motion
causing uneven wearing and pain.
Treatment
Arthroscopy is a surgical technique that
utilizes a small instrument with a magnifying
lens and a light beam that allows the surgeon
to diagnose and treat many knee problems.
Meniscus can be repaired or removed, depending
on the severity of the injury. The kneecap
can be realigned or smoothed, cartilage
can be shaved or removed and ligaments may
be reconstructed using the arthroscope.
In cases of severe degenerative arthritis,
total knee reconstruction may be recommended.
All treatments are generally accompanied
by a physical therapy regimen specific to
the injury.
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