other. A synovial membrane, which secretes a
lubricating fluid (synovial fluid), lines the inside of
the bursa. This is the same kind of membrane and
fluid that encloses and lubricates the joints. Most
people have between 130 and 160 bursae
throughout their bodies, typically located near
joints. Bursae are vulnerable to INFLAMMATION
(BURSITIS) and fibrosis (scarring), both of which
cause pain and interfere with the bursa’s proper
function.
For further discussion of bursae within the con-
text of musculoskeletal structure and function,
please see the overview section “The Muscu-
loskeletal System.”
See also CARTILAGE; JOINT; LIGAMENT; TENDON.
bursitis INFLAMMATION of a BURSA, a fluid-filled
sac between muscles or between muscles and BONE
that protects tissues from friction during move-
ment. Bursitis is a common condition often associ-
ated with overuse of particular joints though the
joints themselves are normal. Casual terminology
for bursitis often relates it to the activities that
precipitate it, such as tennis elbow. Accidental falls
and blunt blows over bursae may also cause bursi-
tis, particularly of the deep bursae. Bursae near
the shoulder, elbow, hip, and knee are most often
affected. An adult has 130 to 160 bursae through-
out the body, any of which may become inflamed.
The primary symptoms of bursitis are PAINand
swelling in the area of the involved bursa. When
there is also FEVER, an INFECTIONmay be the cause
of the bursitis. Bursitis due to infection often
requires surgical debridement (opening the bursa
to remove damaged tissue and accumulated pus)
and treatment with ANTIBIOTIC MEDICATIONS. Inter-
mittent cold packs over the affected area during
the first 48 hours of symptoms may slow inflam-
mation and relieve pain. After 48 hours intermit-
tent heat provides greater relief. NONSTEROIDAL
ANTI-INFLAMMATORY DRUGS(NSAIDS) further relieve
inflammation and pain.
Most bursitis improves in two to six weeks with
such treatment. The doctor may inject a steroid
medication, alone or in combination with a local
anesthetic agent, into a bursa that is causing
severe or chronic pain and restricting range of
motion. Though resting the affected JOINTis help-
ful in the early stages when the bursitis is most
uncomfortable, regular physical activity hastens
HEALINGand maintains full function of the joint.
See also MUSCLE; OSGOOD-SCHLATTER DISEASE;
OSTEOARTHRITIS; REPETITIVE MOTION INJURIES; RHEUMA-
TOID ARTHRITIS; TENDONITIS.312 The Musculoskeletal System