The shoulder joint is a
ball-and-socket joint that allows the arm to rotate in a
circular fashion or hinge away from the body. The "ball" is
the top, rounded portion of the upper arm bone (or humerus),
whilst the "socket," is a dish-shaped part of the outer edge
of the scapula into which the ball fits (the glenoid.) The
acromioclavicular (AC) joint is located between the acromion
(part of the scapula that forms the highest point of the
shoulder) and the clavicle.
As with all other joints, the bones of the shoulder are held
in place by muscles, tendons, and ligaments. Tendons are
tough cords of tissue that attach the muscles to bone and
assist the muscles in moving the joint. Ligaments attach
bones to each other, providing stability.
The rotator cuff is a structure composed of tendons that,
with associated muscles, holds the ball at the top of the
humerus in the glenoid socket and provides mobility and
strength to the shoulder joint.
Shoulder injuries can be caused by sports activities that
involve excessive overhead motion like swimming, tennis and
weightlifting. People involved in some everyday activities
also get shoulder injuries due to excessive overhead arm
motion. Athletes are especially susceptible to shoulder
problems, which can develop slowly through repetitive,
intensive training routines.
Most problems in the shoulder involve the muscles,
ligaments, and tendons rather than bones.
Early detection is the key to preventing serious shoulder
injuries. If detected early enough, a series of exercises
can be carried out aimed at strengthening shoulder muscles
and anti-inflammatory medication may be prescribed to reduce
pain and swelling.
Joint replacement is the final treatment option, for those
cases where all other treatments have failed or are not
suitable.
The most common reasons for replacing the shoulder joint are
for arthritis, either osteo-arthritis (wear and tear) or
rheumatoid arthritis. It may also be necessary following a
fracture or bad accident. With arthritis the joint becomes
painful and difficult to move. Sometimes the rotator cuff,
which controls shoulder movements, is also worn or damaged.
